Chapter 1. Introduction to Bullet Swaging

Good morning! I'm Dave Corbin, and for more than 20 years, I've been helping people make the state-of-the art bullets you read about in articles and magazine ads. Nearly every custom bullet maker in the world started with equipment developed at the Corbin die-works.

Yet, it seems that only yesterday my brother, Richard, and I were debating whether there was any possibility that someone could use our equipment to make a respectable living, producing custom bullets.

All you have to do is scan the pages of nearly any magazine catering to handloaders, and you'll see that the pages are full of ads from our clients; the articles are constantly talking about the bullets our clients make, and the major ammunition firms are buying the bullets made on Corbin equipment for use in major name brands of ammunition (the premium offerings, of course).

Corbin Manufacturing publishes a book called the "World Directory of Custom Bullet Makers" listing hundreds of individuals and firms whose names you will recognize if you like to read gun magazines. When I read the list, I remember people's enthusiasm for the new bullets that we were able to design tooling to make, and figure out a good way to market, thanks to the power of bullet swaging.

Olympians and world champions in every field of firearms sports, from benchrest to air gun competition, using everything from paper-patched muzzle loaders to custom fin-stabilized shotgun slugs, have come to the die-works where my brother and I have toiled for the last quarter century, some just to improve their already-outstanding achievements, and some to help others become better shooters by manufacturing their own best ideas in how a given bullet should look and be constructed.

Engineers from the Department of the Army, Air Force Armament Labs, Sandia National Laboratories, DuPont, Northrop, and other defense-related organization have visited us over those years. Tools and designs we worked on are in use today all over the world, wherever a long range, high precision projectile or a very special purpose bullet, that could only be made efficiently by the high precision techniques of swaging, is needed for the job.

Whether it is protecting a President at long range or picking a pine cone from the top of an experimental tree, whether it is surveying a dense mountain jungle with remotely launched flare projectiles designed for vertical firing stability, or stitching mirror-based bullets in an arctic ice sheet from a low-flying aircraft so a laser beam can measure the depth and estimate the strength of the ice to hold a transport plane, or whether it is the grim responsibility of instantly stopping a drug-crazed terrorist before he can take the life of another hostage—regardless of the purpose, we sat through many meetings pouring over blueprints, computer readouts, and sketches on the backs of dinner napkins, helping design projectiles for visitors from the far corners of the earth.

Yet, this work is only the continuation of development begun by other pioneers of bullet swaging: people like Ted Smith, who founded the old SAS Dies in the 1950's; Harvey Donaldson, who experimented with some of the first dies to make .224 bullets from fired .22 cases; Walt Astles and Ray Biehler, who developed the principle of upward expansion and the two-die swage technique (as opposed to the RCBS single-die take-apart system); Charlie Heckman, a pioneer swage maker; and so many others whose names probably are unknown to modern shooters, but to whom all shooters owe a debt for their contributions to the perfection of bullets.

You may know that the RCBS company (initials of which mean Rock Chuck Bullet Swage) got started making bullet swaging equipment, but soon dropped it in favor of much more easily produced reloading dies. You may even have heard Speer Bullets was started by Vernon Speer swaging .224 caliber bullets from fired .22 LR cases.

But bullet swaging played a much larger part in leading to the products and companies you use today than just that: Hornady, Sierra, Nosler, Barnes, and a host of other mass production operations owe their very existence to the concept of bullet swaging. Today, more than three hundred and fifty custom bullet firms—operated by people who probably differ from yourself only in having taken the step of putting their intense interest in firearms to work at a profitable and enjoyable occupation—make a full-time living by producing specialty bullets.

So, what is bullet swaging and how do you do it? What do you need to get started? How much does it cost? What are the advantages and drawbacks compared to casting or just buying factory bullets? Can you swage hard lead, make partitioned bullets, make your own jackets, make plain lead bullets or paper patched slugs?

I answer those questions a thousand times a week and I never get tired of it. But to save you a lot of time on the phone, I've written those answers here. If you read through this book and think I have left something out, you are absolutely right: I left out about six more books of information! Those are available if you care to read further.

Swaging is so simple you can do it correctly after just a couple of tries. Then you'll see it's also extremely versatile and powerful: you can do one more thing, and then one more after that, and soon, you will have the whole top of your loading bench covered with one-of-a-kind bullets, some of which no one in the world has ever made before. And that's why it takes at least six more books to make a dent in the vast array of things you might do, could do, if you wished. Only your imagination limits the possibilities.

A deeper study of the specifics of bullet swaging technique and tooling, including products made by people other than Corbin, can be found in the book "Re-Discover Swaging", so named because swaging was, in fact, discovered once before and then almost lost: during the period of 19481963 there were many die-makers who produced swaging equipment, but none of them offered a comprehensive enough range of products to insure their own survival, or that of the swaging arts. Corbin Manufacturing was the first comprehensive effort to preserve and further the technology with information, supplies and tools from one source.

Bullet swaging, by the way, is pronounced "SWAY-JING" and rhymes with "paging". There is a blacksmith technique for pounding hot metal around a form that is called "swedging" but it is a different sort of thing altogether.

If you want to really dig into the subject and learn things most people—including most gun writers, unfortunately—never find out, then order the Book Package. You get another copy of this book free, with it. Give this copy to a friend. Who knows: maybe between the two of you, a new bullet making business may develop that rivals the fame of some of our other clients? It could happen: it has happened over 350 times so far!

Chapter 2. Principles of Bullet Swaging

When we say "bullet", the projectile or part of the cartridge that is propelled through the air is indicated. The news media in the United States often refers to a "bullet" as the entire cartridge with powder, primer, bullet and case. Bullet swaging has nothing to do with the rest of the cartridge, but concentrates on the part that flies to the target. In some countries, notably England, shooters refer to the bullet as the "head" or the "bullet head" and call the entire cartridge a "bullet".

There is a good reason not to call the cartridge a bullet, as the general news media seems inclined to do. The bullet is inert metal without any explosive or propellant involved, which means that it should be treated as a precise metal product, not some dangerous, risk-laden component subject to transportation restrictions and tariffs.

Finding a "bullet" in the possession of an airline traveller should be no more cause for alarm than finding a coin. Unfortunately, through ignorance and imprecise language, the term "bullet" causes problems where it should not. Some of them are of practical concern to those who show their products and must carry samples. More than one new bullet maker has run up against unrealistic insurance, business licensing and zoning problems because of the ignorance about what a "bullet" actually means.

A bullet maker is a precision metal product manufacturer, who could just as well be making precision bearings or electronic fittings. But try to explain that to a bureaucrat who just found out you intend to make bullets in the home enterprise, or the hysterical airline security guard who scanned a couple of samples in your pocket, or the customs agent whose eyes widen as he reads your declaration of "bullet-making" equipment being taken into the country! Such a pity these things happen. The wise bullet-maker soon learns to discuss precision formed parts rather than bullets, around those who know nothing about the field.

Bullet swaging is the process of applying extremely high pressures (from 15,000 PSI for soft, unjacketed bullets to as high as 200,000 PSI for solid copper bullets) to bullet metals contained in a very tough, extremely well finished die, so that the material will flow at room temperature and take on the shape of the die and the ends of the punches.

A die is a vessel to hold the pressure. A punch is a rod that fits into the hole in the die and seals off the end. If you refer to a punch as a die and vice versa, you may cause some interesting errors when placing orders. One of the first things to learn is the right names for the basic parts involved in the swaging process. You wouldn't call a pistol a shotgun, would you? Probably not, or else you might get some odd-looking holsters through mail order!

It concerns me that some people don't bother to learn the difference between a die and a punch, and consequently have a string of fouled-up orders that must be carefully untangled. But then, I'm an old curmudgeon and can grouse about anything I like, `cause that's the rule for curmudgeons (Rule 109, look it up in the curmudgeon book).

My foreign friends, whose mastery of the English language is far superior to anything I could claim in their native tongues, may be forgiven for such errors. It is interesting how seldom someone from a Spanish, French, Portuguese, Italian, Dutch, Afrikaans, Greek, Arabic, or Hebrew speaking country ever makes these basic errors: I'm afraid I have to point the accusing finger at my British, Australian, Canadian, Kiwi and `merican speaking mates as the worst benders of terminology.

It wouldn't be any bother to me at all, if I didn't have to figure out what a person really wanted. For casual conversation around the campfire, no harm is done if someone calls a revolver a pistol or a die a punch. But a person who really wants a die and gets the punch that they actually ordered isn't usually very happy about it.

In swaging bullets, you will always be putting a smaller diameter object (lead, jacket, or a combination of both) into a slightly larger die cavity or hole. Each step in swaging increases the diameter of the components, until they reach the final diameter in the last die. Swaging never reduces the diameter. You will only have stuck bullets and hard ejection if you try to push a slightly larger part into a slightly smaller hole. This is the difference between swaging and drawing. You never swage anything "down". You never draw anything "up".

In drawing, you do push a larger part through a smaller hole, to reduce the diameter. This kind of die is a ring, not a cylinder closed on one end. The jacket or bullet that you are reducing is pushed through the ring, and is decreased in diameter when it comes through the other side.

We use drawing to make longer, smaller caliber jackets from shorter, larger diameter ones. Also, within some narrow limits, it is possible to make a smaller caliber bullet from a larger one, although this degrades the quality of the bullet unless very special conditions are observed. Usually the difference in diameters has to be within 0.005 thousandths of an inch when you reduce finished bullets by drawing. Jackets can be drawn much more than this.

Bullet jackets properly designed for swaging are always made smaller than the finished caliber, then expanded by putting lead inside them and compressing it with a punch. The lead flows to fill the jacket, then pushes the jacket out a few thousandths of an inch to meet the die wall, which stops the expansion. One end of the die is sealed with a punch, which stops the end from popping off the jacket. If you try to use a jacket larger than the die hole, it can't spring back slightly when you release the pressure. In fact, if you pushed a jacket into a die that was too small for it, the jacket will be trying to spring back to original size, and thus pressing itself firmly against the die walls. This causes difficult ejection and is hard on the equipment, and can also result in loose cores.

The right way to swage bullets is to use jackets that fit easily into the die by hand, and lead cores which are small enough to easily drop into the jacket. Jackets of course have some wall thickness, generally from 0.015 to 0.035 inches (although there is no rule that says you can't make much thicker jacket walls if you want them). To determine the diameter of lead core which fits inside, you must subtract two times the wall thickness from the caliber, and then subtract an additional five to ten thousandths of an inch to allow for easy insertion, tolerances in the lead wire diameter, and the fact that you may have two or three steps with a small amount of expansion in each, to get to final caliber.

There are two basic designs of swaging dies made by Corbin. All the specific styles of dies are patterned after one or the other of these basic designs. One design is a cylinder with a straight hole through it. The other is a cylinder with a semi-blind hole, having the shape of the bullet except that at the tip, there is a tiny hole (.052 to .120 inches is a typical range) fitted with a strong piece of tempered spring wire.

The first design can be used for any sort of operation where two punches can form the desired shape on the end of the enclosed materials. An example would be a "Core Swage" or "CSW-" die, which takes in a piece of cut lead wire or cast lead pellet (the "core" of a bullet) and gives it a precise diameter with smooth flat ends and extrudes off whatever surplus lead there might be for the weight you have set up. Three little bleed holes in the sides of the die, at 120 degree intervals, allow surplus lead to spurt out as tiny wires which are sheared off during ejection. Core swages are used to make the lead filling (core) a precise weight after it has been cast from scrap lead, or cut from a piece of lead wire.

This kind of die can also be equipped with a punch having the shape you want for the bullet base, and another punch, at the opposite end, having the shape you want for the nose. Both shapes will be in reverse: the bullet nose is formed in a cavity in the punch, and a hollow base bullet would use a convex or projecting punch. If you do that, you have what we call a "Lead Semi-Wadcutter" or "LSWC-" type of die. That doesn't mean you have to make a particular shape that you know as a semi-wadcutter bullet; it's just a short-hand way of saying you could do that, or make any other shape that has the entire nose right out to the full bullet diameter formed by pushing the lead into a cavity in the end of the nose forming punch.

On the following pages, you'll see an illustration of a LSWC type die. One punch always stays partly inside the die. It slides back until a ledge within the swaging press ram stops it. To eject the bullet out of the die, this punch is pushed down. It can be pushed by a pin incorporated in the design of the press (with a Corbin swage press), or it can be pushed by a plunger or a special ejection tool (with a standard reloading press). We call this punch the "Internal Punch" because it always stays in the die. It is "internal" or inside, and never comes out during normal operation. It merely slides up and down, a distance slightly less than the die length, and stops within the die so as to close one end for swaging. It has to move from this position to the die mouth, in order to push out the finished bullet.

The other end of the die is where you push in the material to be swaged. Obviously, that end has to be fitted with a punch that comes out all the way. Otherwise, there would be no way to put the material inside. The punch which comes out, so you can insert material into the die, is the "External Punch". It is external to the die during the time you are placing the components in the die, and when you move the ram back to eject the bullet. The "Ram" is the moving tubular steel part of the swaging press that holds the die and the internal punch (in any Corbin press). The external punch fits into an adjustable "Floating Punch Holder", in the press head or top. This assembly is often mistaken for the swage die, because in reloading, a similar-appearing reloading die fits the head of your reloading press. Swaging is "upside-down" from reloading, for reasons that will be clear by the time you finish this book.

Again, the steel rods that push the material into the die, and seal the die against all that pressure during swaging, are called "punches". The round cylinder with the hole in it is called the "die". If you fit punches to a particular die, you have just made a "die set", because it is a set of matching parts that work together. You can have several dies and punches in a given set, because all the various dies in that set are designed to work in succession, one after another, to yield a final bullet shape, weight, and construction.

The only difference between a "Core Swage" die, which we call a "CSW" die in the language of swaging, and a "LSWC" die, is the use of punches which have the final bullet base and nose shape machined on their ends, and of course the diameter of the die is made to form the final bullet diameter in the LSWC die. Usually the LSWC type of die makes either lead bullets, gas checked, half-jacketed or "Base-Guard" bullets (a superior kind of gas check that scrapes fouling out of your barrel with every shot fired). It isn't used for bullets that have the jacket covering up the bleed holes in the die wall, which includes most jacketed rifle bullet designs.

The core swage die generally has flat punch ends and a diameter far less than the final caliber. It is used to prepare the lead core to fit inside a bullet jacket, in most cases (although you don't have to use a jacket—you can just swage the lead core to final shape in the next die if you desire to make a high quality lead bullet, such as a paper-patched or Gase-Guard style). Lead bullets can be made either in one die (the LSWC) or in two dies (the CSW and CS types, or the CSW and PF types). Jacketed bullets generally require at least two and sometimes three or more dies.

When we make the die, we need to know what it will be used for. If you say you want a .308 core swage die, we know you don't really want the hole to be .308 inches because a core swage has to make a core that fits inside a jacket, and the jacket will usually be about .307 inches on the outside before swaging. The wall thickness of the jacket might be .025 inches at the base, so the core would have to be no larger than .307 minus twice .025 (twice the wall thickness), or .257 inches.

You would cast scrap lead in a core mould, or cut pieces from a spool of .250 inch diameter lead wire to easily drop into this .257 bore die, swage them up to .257 inch diameter, and then they'd fit nicely into the bullet jacket. (There would be two more steps to expand the core inside the jacket, blowing the jacket out like the skin of a balloon, and then forming the ogive on the bullet to finish it).

But if you wanted to make a lead .308 diameter bullet for a .30 Mauser, then we'd make almost the same kind of die but we'd make it with a bore of .308 inches, and fit it with the right kind of nose and base punches. So you see that even if the dies look similar and work in a similar way, their purpose really makes them different dies. That's why we need two different names for them. It helps avoid a lot of unnecessary explanation and errors. Perhaps you might order a .308 LSWC die, maybe with an "Auto-loader" nose and a "Cup Base". We would use the short-hand "AL" for Auto-loader, a sort of rounded semi-wadcutter shape, and "CB" for Cup Base, which is a shallow concave base form. To us, the term "semi-wadcutter" is a general description for a bullet style that can be made using a punch to form the nose, instead of a point forming die. The wadcutter, Keith, Auto-Loader, and even round nose SWC styles are all subsets of the semi-wadcutter group, since every one of these styles is made in the same die just by changing the nose punch.

Two other kinds of dies that are made with a straight hole and two full-diameter punches are the "Lead Tip" die and the "Core Seat" die. These don't have any bleed holes around their middle. The core seat die is also called a "Core Seater" and abbreviated "CS". The lead tip die is also called a "Lead Tip Former" and is abbreviated "LT". It is not the same thing as a point former or "PF" die.

The purpose of a core seat die is to expand the jacket, which is made slightly less than final diameter, and at the same time achieve a very tight fit between the core and jacket. You can use either a punch that fits into the jacket, to make open tip style bullets, or you can use a punch that fits the die bore, and thus make large lead tips. The use of a CS die to make lead bullets (after first swaging the lead core to exact weight in the CSW die) is a perfectionist's way to build lead wadcutter or semi-wadcutter bullets: it can be more precise because you separate the pressure needed to extrude surplus lead from the pressure required to form the edges of the bullet nose and base.

In a LSCW die, the pressure stops building when the lead begins to extrude through the bleed holes. Thus, some shapes of bullets with deep nose cavities or hollow bases and sharp edges may not receive enough pressure to fully take on the exact punch shape, if that pressure is higher than the pressure which causes lead to spurt out the bleed holes. By first using a CSW die to adjust the weight, and then using a separate CS die to form the nose and base, the pressure issue is resolved for all shapes and styles.

A punch with a cavity in the end makes the bullet with a semi-wadcutter shoulder (the edge of the punch must be in the neighborhood of .02 inches thick in order to stand the high swaging pressures). A core seating punch with a projection on the end, usually conical, makes a hollow point cavity in the lead core. Of course, you can use flat, domed, slightly convex, or highly pointed punch shapes to suit your desires, and make virtually any kind of base you want just by changing the punch. Often this will be the internal punch, but you can have the die built with the base punch being external if you wish. The reason we normally make the nose punch external to the die is because usually people change the nose shape much more often than the base, and it is easier to change the external punch in seconds without removing the die from the press ram. Technically it would not matter which punch made the nose and which made the base.

The purpose of the lead tip forming die is to finish the very end of a pointed (spitzer) bullet, and it isn't normally used for semi-wadcutter or large lead tip bullets. It looks just like a core seater, but the bore diameter is slightly larger than the final bullet size, whereas the core seater diameter is just slightly smaller than final bullet size. The internal punch of a lead tip die is designed with a cavity to reshape the extruded lead tip of a sharp-pointed rifle bullet so that it looks perfect. It cannot form the entire ogive because the edge of the punch, which must withstand tons of swaging pressure, cannot be paper-thin and survive.

We started this section talking about two general die designs, one with a straight hole through it, and one with a semi-blind hole. This second kind of die came about because, try as you will, there isn't a reliable way to make a straight-hole die form a smooth ogive curve from shank to tip. That punch with the cavity machined in the end must have some thickness at the edge, and this edge will impress itself on the bullet to make a shoulder.

There's even more to it than that: if you try to push a jacket into the cavity in the punch, the edge of the jacket will strike the edge of the punch. It won't reliably jump over that edge, but instead either the jacket or the punch will be crumpled up. In Corbin dies, the jacket is far weaker than the punch, so it folds up. So, that leaves the problem of how to make a typical rifle-style bullet, or a smooth rounded or angled bullet nose of any type, not having a lead tip from where the jacket stops to the end of the bullet.

The semi-blind hole die is used whenever the nose or base of the bullet has to turn inward, away from full bore diameter, without a shoulder or step. Conventional rifle bullets, boattail bullets, and modern jacketed handgun bullets with the jacket curving or angling smoothly inward from the shank to the ogive all require the use of this die design.

By "semi-blind hole", I mean that the hole in the die is not straight through the die, but is shaped like the bullet itself. At the tip is a very small punch to push the bullet out by its nose, and this punch is retracted a short way up into its little access hole so there is no possibility of the bullet material pressing against it (which might otherwise bend the small diameter punch under those tons of pressure).

A straight-hole kind of die uses a punch, with a cavity machined in the end, to form the bullet nose. The edge of the punch would strike the edge of a jacket and crush the jacket. A punch edge must be .02 inches or more thick to stand up to swaging forces: making the punch edge "paper-thin" so that the jacket might stand a chance of jumping over it doesn't work for long, because the thin punch edge soon cracks and falls off under the high pressure. You wind up with a ragged .02 inch edge anyway!

There are only a few dies that use this semi-blind hole design. One is the "Point Forming" die, which we abbreviate "PF" die. It accepts either a lead core, or the seated lead core and jacket combination swaged in the core seat die. A full-diameter external punch shoves the material into the point forming die. The material is compressed inward in the small end of the die, giving the bullet its smooth curve or angled nose (the ogive).

The bullet material follows the die wall, right up to the ejection pin hole and into it, if you push too far. This would put a little parallel "pipe" on the tip of the bullet, which means you need to back off the depth adjustment (the punch holder) just a little. The smallest tip which you can put on the bullet using the PF die is the diameter of the ejection pin. The smallest ejection pin that can be used is one that will withstand the ejection pressure without bending. If you happen to forget to apply swaging lubricant, or if the jacket is larger than the die cavity diameter, the pressure required to eject the bullet can go considerably higher than the design parameters. This means that the ejection pin needs a little extra diameter as a safety margin.

A typical ejection pin (the internal punch for a point forming die is usually called an ejection pin) for .224 or .243 caliber might be in the .062 to .081 inch diameter range, depending on the expected ejection pressures and the abuse expected for the die. Dies made for professional bullet makers, who know how to stop short of bending the punch if anything goes wrong and who won't be upset if they do need to replace the ejection pin now and then, might tend to be closer to .062 inch; dies made for experimenters who will be exceeding the design limits frequently tend to have larger ejection pins, as do dies made especially for lead tip bullets.

If you make a round nose bullet, a truncated conical pistol bullet, or even a flat tip rifle bullet in the PF die, it works very nicely without using a special LT forming die. You have a finished product. If you make a bullet with the jacket curved around to the diameter of the ejection pin, then the pin will press down against the end of the jacket and push the bullet out of a well-finished, diamond-lapped swage die with relatively low force. Again, no problem. But if you want a small, sharp or rounded lead tip, the ejection pin spoils your plan by making its own flat circle on the very tip of the bullet.

To form a small lead tip on the bullet, you would need to leave a little extra lead projecting from the end, let the ejection pin deform it somewhat during ejection, and then use a "lead tip forming" die, or "LT" die, to shape up and shear off any extra lead. The lead tip die accepts the nearly-completed bullet from a point form die, so it has a bore diameter slightly larger than the finished bullet size. This works only because the pressure needed to shape the lead tip is so low that the bullet shank will not expand. In fact, since the lead tip die just minutely larger than the point forming die, perhaps only .0001 inches, it can assure that the bullets will be more parallel and have almost no "pressure ring" at the base.

The internal punch of the lead tip die has a cavity that is shaped not exactly to the same outline as the bullet ogive, but with a slightly shorter radius. For instance, if the bullet had an 8-S ogive (we'll explain this in detail later, but the ogive radius is the length of the radius used to swing the arc that gives the bullet ogive its shape), the radius of the cavity shape inside the lead tip forming punch would be perhaps 7S. That is a shorter radius.

The result is that the lead tip is formed and the surplus lead pushed down at a slight shear angle between the wall of the punch and the ogive of the bullet. If you leave the right amount of exposed lead, the surplus will be sheared off neatly, leaving only a neat lead tip with a very slightly different ogive curve from the rest of the bullet. It will look very nice.

Bear in mind that the LT die is not used by itself, nor is it used instead of a PF die. If you use one at all, it would be to follow a point forming die. Remember, the jacket edge won't jump over the punch edge. If you already have a curved jacket, from the PF die, then the edge will slip past the cavity and let you shape the lead tip.

A LT die can also be used, in some cases, to help close the open tip of a jacketed bullet more tightly than could be done in the PF die alone. With care, a bullet maker can learn to push the open end of the jacket nearly closed, by gently using trial and error adjustment of the punch holder. Not every ogive shape or design lends itself well to this operation, but enough of them do so that it is worth mentioning.

What about bevel bases or boattail bullets? Those also have the bullet smoothly angled away from full shank diameter. So, they also require a variety of the point forming die. The boattail bullet has largely been replaced in swaging circles by the superior "rebated" boattail, abbreviated "RBT" as opposed to the more conventional "BT" for boattail.

I would love to launch into a long-winded mathematical discussion about why a rebated boattail beats a standard boattail, but let me just give three fast ones:

First reason: a regular boattail bullet tends to act like the focusing nozzle of a water hose during the moment it emerges from the barrel. Hot powder gas rushes around that boattail angle, flow up the sides of the bullet, and continue in a smooth, laminar low pattern right around the front, where they break up into turbulent flow and make a fireball of gas—right in the path of the bullet!

You can get up to 15% increased dispersion at the target just from the buffeting the bullet gets by shooting through this ball of gas. A flat base bullet deflects most of the gas in a circle of fire, expanding rapidly out from the bore with a clear space directly in front of the bullet. The edge of the flat base acts like a "spoiler" to break up the laminar flow before it can get started. And so does the sharp shoulder on a rebated boattail! How does an extra 15% improvement in accuracy sound as one reason to use the RBT design?

Second reason: the boattail bullet tends toward more bore erosion than the rebated boattail, because gas pressure on the boattail tends to peel it back away from the bore and let some gas up past the bottoms of the rifling grooves, where it cuts the bullet and the barrel like a hot cutting torch. The rebated boattail has a 90 degree shoulder that takes the pressure parallel to the bore, instead of at a compression angle away from it. How does increased barrel life strike you as a second reason for using RBT bullets instead of the regular BT style?

Third reason: the tooling lasts longer, costs less to build, and is more easily built to high standards of precision. Corbin Manufacturing has perfected a method of using two semi-blind hole style dies, which we call the "Boattail 1" and the "Boattail 2" dies, as a set, to produce a virtually flawless and highly repeatable rebated boattail. Instead of making the boattail angle so it can be higher on one side or at a little slope like some of the factory production you see today, this system guarantees that the boattail will start precisely at the same point on one side of the bullet as it does on the other, every time.

Neither my brother nor myself wants to fool with the BT after all these years of match-winning, record-setting results, so we don't make regular BT dies.

All this is documented in greater detail, with mathematical proofs, in a 1970's era report by Dr. Fitzgerald of Scotland, who conducted a study at the Lapua (Finland) factory. Lapua first developed the RBT design, or at least made it popular among target shooters. The good doctor was kind enough to send me a copy of his work "way back when". The paper is primarily for people with a strong calculus background, and isn't especially easy reading, but the conclusions are clear enough.

Bevel base bullets are made by seating the core in a special point forming die instead of the usual core seating die. The jacket is put into the die, and the lead is pushed into the jacket. The base of the bullet flows down into the short, beveled section of the die (it can't be a punch cavity, remember, because the edge of the punch would just cut the bottom of the jacket). You could also seat the bullet as usual and then reform the base in this die.

A lead bullet bevel base bullet could be made in two steps: swage the lead core using a rather large, almost finished diameter core swage, and then push the bullet into the special point forming die backward, using a nose punch as the external punch. Come to think of it, any lead bullet with a smooth ogive (no semi-wadcutter shoulder) can best be made by using first a CSW die to adjust the weight, and then a PF die to form the ogive. Without a jacket, you don't need the CS die, the purpose of which is to expand the core into the jacket and form a tight, parallel shank.

We've talked about the basic design of bullet swage dies, in regard to their function. There is another category for classification of swage dies, and that is by the kind of press used to operate them. Swaging dies can be designed to operate in a reloading press (with severe limitations on pressure and precision), or in a number of different models of bullet swaging presses, both hand and hydraulic-electric powered.

Years ago, we worked out a system of making standard parts for dies that would cover a wide range of calibers, and thus cut the cost of swaging through efficient use of what I call "semi-custom production". My brother Richard and I designed presses and die sets so that we could build similar punch and die blanks for certain ranges of calibers and bullet lengths, and then choose among perhaps three die body lengths for every caliber from .14 to .458 in the hand presses, or from .224 to 20mm in the dies for our big hydraulic presses.

We didn't have to design and build each die from scratch, because we built a standardized system for determining the minimum requirements of strength, die length, stroke length, punch geometry and strength, steels and heat treatment. We could run hundreds of blanks for each of the various presses, then hand-finish the cavities and hone the rough-finished punch blanks to a perfect fit during the custom phase of each order. It combined the economy of mass production with the flexibility and precision of custom tooling.

Corbin swaging dies are up to ten times less costly than competitive dies without any sacrifice in precision because of this semi-custom production technique, and the fact that we design and build several different presses to take full advantage of the kind of operations you might want to undertake. No other firm builds as many different styles of swaging presses, or matched systems of dies, and that is one reason we have been buried in orders for decades, sometimes with backlogs that went back two years or more! We built a new plant in 1984 primarily because the waiting list for our dies had reached nearly three years, and hardly anyone wanted to cancel their orders. The new die-works helped, but demand has grown constantly, steadily, and sometimes with big spurts (just after the 1986 gun laws and the Brady bills went into effect, we had more orders in a single month than in the previous quarter).

For years, so many people have been making a living with this equipment and setting world records of every type with the bullets that there is no longer any reason to doubt that the process works better than any alternative method (such as casting or lathe turning) and the business aspects of custom swaging are viable. If you know anything about modern bullet design, you have already heard about the Corbin Hydro-press, since nearly every custom bullet maker in the world uses one. There are six other Corbin swaging presses, including three hand operated models and three other hydraulic/electric models. We'll cover them individually along with the dies in later chapters.

Remember these swaging principles:

• 1. Never swage down; always swage up in diameter. Punches and components should slip into the next die by hand, or else they shouldn't be put in at all.
  
• 2. Use only enough force to expand the material to the diameter of the die bore and then stop. If the material won't completely fill out the die with normal pressure, there is something else wrong. Look for excess trapped lubricant or too hard an alloy of lead for the particular shape and method.
  
• 3. Work carefully and be gentle when moving the ram. Don't whip the handle up and down as fast as you can, because you will surely slam the punch into the face of the die sooner or later and wreck it. You can get better speed with a nice steady pace rather than brute force!
  
• 4. Pay attention to instructions that recommend the use of soft lead, or annealing the jacket, or using the right lubricant. There's a good reason. All the downstream steps are affected by missing one upstream.
  
• 5. Use the correct thickness and type of materials for the particular dies or punches, and use the right punch in the right die. It is amazing how many times the only problem is that someone used the wrong punch, or material.
  
• 6. Read about the process before you try it, to save time, needless investment in the wrong tools, and frustration. Corbin publishes eight books and many software programs to assist you. That's far more than was available to the shooters of the past. It's a good time to be a bullet-maker!

Chapter 3. Bullet Swaging Secrets

Before I start telling you about the various kinds of swaging presses and dies that work with them, and why you might want to select a given type of press and die for a certain kind of bullet making, it would be useful for you to know some facts that have taken decades to figure out, and which most of the people who have figured them out wish to keep secret from you, since it might affect their own income if you knew.

The most common misconception about bullet swaging is that only a few people really have the money and expertise to do it right—that the equipment to make a good bullet is far too costly for you to buy, and the techniques are filled with "secrets" that only a few bullet-makers are smart enough to understand.

Horse-feathers!

The reason this myth is repeated in print every year is simple. Think about it: if you were making a reasonably good income from selling your own custom swaged bullets and someone asked you to tell a magazine audience, through an interview and an article, all about your business, would you tell them "Hey, it's easy: anybody can do it with a little reading and a few hours of experimenting with moderately priced equipment!"

Or, would you be more likely to think long and hard about it and then say "Man, it's tough: the only equipment that works costs thousands of dollars and takes years to figure out. You guys are way better off just to pay me to do it for you and keep on buying my bullets!"?

Always remember to consider the source when you read anything, and follow the money trail. Forget for a second that I'm also selling products and services: that's advice from me to you on a personal level. It works in almost everything in life, not just bullet swaging. Before you read something, try to figure out who wrote it, who pays them, and why they might be influenced in their comments and opinions by the source of their income.

Often the connection is two or three layers deep: the writer might not be "on the payroll" of the person about whom he is writing, but perhaps the owners of the media he is selling the article through have a vested interest in protecting advertising revenue from someone who might be harmed if the absolute truth were printed instead of a slightly shaded version.

It's not a conspiracy: it's just how life works. Everyone has an interest in protecting their source of income. The more unusual the occupation, the less likely it is that the person will say anything that would encourage you to go into competition. Successful people learn early how to get good information from shaded stories without necessarily accepting everything at face value.

All this means is that when you read articles by or about bullet makers or their products, be aware that the products were made by human beings, not mythological Titans. Odds are pretty good that, given the right equipment and information, you could do the same thing. Or maybe, even better.

Long ago, I sold a successful electronics company and was able to spend a few years playing with various ideas before getting serious about starting another company. I loved writing historical articles about the firearms field. Firearms played a much larger part of our unique national history than just their dramatic involvement in winning the West. They are woven into the very fabric of our industrial, technological and financial history in a very positive way.

Like space research and computers today, firearms contributed to our technology and general well being in many ways during the early development of the United States. I wanted to do something worthwhile to help shooters, and to be involved on a day to day basis in the field that I enjoyed so much.

I decided to devote my time to the development bullet swaging. I did it to preserve an art that I felt was worthwhile and on the verge of dying, as well as for my own enjoyment, and to make a living by helping others start their own bullet-manufacturing firms.

I had made enough money in my other business activities so that I didn't need to earn very much for several years, and could afford to spend the time as needed. I divided my time among writing, developing new businesses for other people, and building what was eventually to become the world's largest bullet swaging tool company.

This latter activity would keep me honest regardless of any other motivation, since there simply are not enough people who meet the criteria to be commercial bullet-makers to build a business based on anything other than repeat business from people who are successful. Being successful at the development of swaging equipment meant more than just selling tools to handloaders: it meant developing the commercial market for specialty swaged bullets and helping handloaders become successful bullet makers. The repeat business from their growth was necessary to fuel the continued growth of my company.

There are not enough potential bullet makers to treat clients like used car buyers, even if I could somehow justify acting that way. Either my clients would have to be successful, and continue to purchase equipment and supplies as they grew, or the swage die business would not work well enough to be viable. Although I had earned enough so that I could afford to try this, I certainly couldn't justify running it into the ground! Only a fool wastes money on ventures that have no chance of success.

After more than two decades of providing income for six families of Corbin employees, it's fairly obvious that there must be something behind the ideas I am discussing here. It's not very likely that thousands of handloaders would come back, year after year, for products and ideas that didn't meet or exceed their expectations.

Many people do, in fact, make a good living using Corbin equipment to produce high quality custom bullets for other shooters. You see their ads every time you pick up a gun magazine. They start small, often just as a hobby, and their interest and business grows and expands to other equipment, which Corbin designs and manufactures. Our design and engineering work, as well as marketing help, is critical to the success of most of our clients (there are some who had everything figured out from the start, but not many).

Because a substantial part of our income and reason for our own success has been based on appropriate advice and honest dealing with our clients, your trust is a critical factor in Corbin's very existence. We continue to have backlogs for our work primarily because people know that they can trust in the essential facts that are spelled out in our books.

You'll probably read things here that I say are not practical today, and perhaps years from this writing they will be. Maybe you are reading this years from when I wrote it, and I will contradict the literature published at that time. New ideas and products will develop to make those changes. That's progress! But by and large, the principles are well established by now, even if some techniques and tools will change.

I have promised my clients that I will not compete with them, or reveal their own secrets regarding discoveries they have made on their own about how to make better bullets for some special purpose, and I don't. It is extremely tempting to manufacture custom bullets myself. If I had known how very profitable the field was going to turn out to be, decades ago, I would probably never had made any equipment for other people. I would have made dies and presses for my own use and just manufactured exotic, highly profitable bullets. What better product to sell than one for which the sole purpose is to use it up in a one quick shot and then get another one!

But back then, I didn't really think there was much chance that the gun writers, editors, publishers, and the general handloading public who read their work would pay serious attention to custom bullet makers. I assumed my own success would always be limited to a handful of loyal clients because the firearms media would be interested in preserving the advertising income from mass producers, and the limited size of each of the custom bullet markets would mean a custom bullet maker wouldn't count for much with the firearms press.

No matter how much better bullet a person working in their garage could build on specialized, low-volume swaging equipment, I felt that Winchester, Remington, Speer, Hornady, Sierra, and maybe a handful of other big advertisers would always be featured in articles and stories, press releases and new product reports. They'd get all the coverage, and thus almost all the sales. The "little guy" making special purpose bullets would be on his own, with just me and perhaps a few enlightened gun writers to help spread the word. For a lot of years, I was partly right. In the past ten or so, I have been mostly wrong!

Today, you can hardly pick up a gun magazine without reading something about one of my clients who makes a better custom bullet. Of course, the big advertisers still get the lion's share of the praise, but that's life. And it's rare for one of them to make anything that isn't touted as the answer to every handloader's prayers, regardless of how mundane the design really might be in comparison to the products of custom bullet makers. Still, the public and the press have elevated custom bullet making from a dark art to a serious, mainstream part of the firearms industry.

You might not care at all about the commercial possibilities for custom bullet making, but it affects you anyway. The mass producers have been forced to come up with their own premium lines of bullets to avoid losing face, and in some cases have purchased bullets from my clients instead of trying to come up with their own. The fact that more than 350 people (as of this writing) have turned to bullet swaging as a way to make a living, and thousands more use it as a way to make a little spare cash on a part-time basis, means that your bullet selection has improved vastly in the past few years.

Guns of a type that you might not have considered using for defense twenty years ago can now be put into service, since the bullets that are now being made for them have improved their performance so much. Game animals that you might have wounded and lost twenty years ago can be cleanly taken without the suffering and without the long hikes to the bottom of canyons where the game was able to run and finally die a lingering death because of poor bullet performance. Hunting is more humane when the bullets perform flawlessly on the first shot.

Your scores at benchrest, metallic silhouette, IPSIC, and even blackpowder matches can be higher than they were "back then" because of the tremendous amount of research and testing done by all the custom bullet makers. Laws have been passed based on certain kinds of custom swaged bullets that did not come from any mass producer. If you don't think you have some interest in commercial swaging already, think again!

Regardless, there are some facts that you should know, because there have been so many myths and smoke-screens thrown up by people who either don't know any better, or have a vested interest in keeping you in the dark about swaging. Bullet swaging puts aside the final barrier between you and the performance of your firearm. It steps right in and hands you the power to find out what works, and what doesn't, if you have the mental capacity to do scientific studies (anyone with good horse sense has that ability: it means comparing "apples to apples", using reasonable control samples and conditions for valid comparisons, and judging performance based on a wide enough base of experiments to be meaningful).

This is damaging to the hype artists. If you can easily find out for yourself that some over-touted design fails to perform as well as your own, it takes the wind out some very costly promotional sails (yes, and sales, too). If you have been reading for years how only some master match-winner turned bullet-maker can possibly make bullets good enough for your rifle, and then you find out in one weekend that your own bullets can outshoot them, there may be a sputtering noise as a highly publicized ego deflates. All of a sudden, you start looking a little harder at what the "big boys" and the experts have been repeating, and maybe you question some of those statements.

The same thing happened when handloading began to look threatening to the commercial ammunition makers decades back. They fought the idea that people could handload their own ammunition. Some of the gunmakers voided the warranties on their guns if handloads were used (since gunmakers also sold ammunition). But handloading was too powerful a tool to fight for too long. After all, muzzle loaders were "handloaded". People made their own bullets and wads, and the advent of cartridges and smokeless powder just continued expanding the possibilities.

Bullets which are cast are not a threat to the large bullet makers because there is so little profit in competing with them. Bullet casting businesses come and go all the time because of the slim margins and intense competition. A cast bullet is a piece of frozen lead. There isn't too much you can do to make it "exotic" or enhance the value and performance.

Swaged bullets open the floodgates of design. The process can be used to make almost anything you can imagine in a bullet. Swaging is the process used by mass producers. You are tramping into their territory. They know that given the right tools, you can make better bullets because the process is only limited by constraints of time and material quality, both of which you can control with less regard to final cost than they must exercise in the mass market.

Those with an interest in protecting their commercial territory would like to see as little as possible in print about swaging. What has been in print in the past several years is just the tip of the iceberg: a great deal more has been going on with bullet design, with private individuals building successful bullet manufacturing operations, and with development of ideas that go far beyond those of mass producers. You have heard a tiny amount compared to the actual state of the art, unless you're involved in swaging already.

There are also a number of myths which are based partly on a desire to keep people out of the field and partly on misunderstanding of the facts. I would like to point out something that you should know about metallurgy, to avoid being "taken" by misleading advertising and opinions of people who don't know what they are talking about. There is a great deal of emphasis placed on the buzzword "carbide" at this time. Carbide is a rather generic term that covers a lot of ground, rather like the word "chlorophyll" back in the 1960's, or any other semi-technical word that is turned into an advertising catchword.

There is no such thing as a single kind of material called "carbide", except in the minds of ad writers. When you heat any tool steel to a high enough temperature, some of the carbon in the material dissolves in the nearby iron, and forms a ferric carbide material which can be captured in the frozen matrix of the steel if the temperature is lowered quickly enough.

The ferric carbide trapped in the steel mixture is primarily what gives the steel its hardness. The structure also has a matrix of iron and other elements, which form complex compounds that give the steel ductility, ability to remain hard at higher temperatures, corrosion and shock resistance. All hardened steels have "carbide" in them: that's what makes them hard.

If you systematically reduced the amount of iron and increased the amount of carbon that dissolved in the iron that was left, you would wind up with a very hard, but also very brittle material. It might be almost "solid carbide" but it wouldn't be very strong. By forming compounds of tungsten and other metals with carbon, the General Electric company (and others) developed commercially acceptable variations of "carbide" in a wide variety of grades. The trade name of "Carboloy" was applied to some of these.

The important thing to note is that there are variations that are nearly as soft as hardened tool steel that have fair shock resistance, and others that are so brittle that they shatter like glass if force is applied incorrectly. Some carbide materials can handle high temperatures and some fracture when heated and cooled during use. Some make good tool bits, and some are only good for a thin coating on the surface of a hardened steel bit. Some are reasonable to machine accurately, and some cost a fortune to machine compared to making the same shape from a good tool steel.

If you were to be faced with the decision of a material from which to build dies for a high speed punch press, working at 40 strokes per minute or more, and making several million bullets, then one of these grades of carbide material could give you higher temperature operation and thus longer life than a tool steel die. Because the harder materials are more abrasion resistant, you would be able to run the dies for a longer time before replacing them.

They would still need to be lubricated: the idea that carbide dies need no lubrication is foolish. It is like saying that because your car engine might run 100,000 miles without changing the oil, you don't need to change the oil. It might run 250,000 miles if you did! And it might run 100,000 miles a lot smoother and cooler with fresh oil.

It is necessary to consider value to make a good decision about die materials. Value is the cost of the die amortized over the number of bullets you expect to make, considering the amount of wear which will take place before the bullets are no longer acceptable quality.

If you operate your dies in a hand-fed system of any type, it will be impossible to make more than five or six bullets a minute. At those stroke rates, any heat from friction would dissipate into the air before the next stroke. There would be minimal heat buildup, so that normal swaging lubricant (Corbin Swage Lube) would be sufficient to protect the die and the components from frictional abrasion.

In a power-fed system, it is possible to stroke the press so fast that heat cannot radiate away into the air as quickly as it is generated, until the die becomes quite warm. It reaches a stable high temperature by radiating heat into the air, and into the frame of the press. Swaging lubricants may not stand this high temperature, so the metal surface needs to be made of something that will remain hard and resist abrasion without lubrication. Certain grades of carbides will handle the job.

Value is indicated by first estimating the tolerances which are acceptable for the bullets, and then figuring out how long a set of dies will give that range of tolerances, and how many bullets are made with each set, for what price. The lowest cost per bullet indicates the best value, all other things being equal.

In the high speed punch press, a set of dies might easily cost $3000. They might slowly wear to an unacceptable tolerance after two million bullets were made, at a cost per bullet of three thousand dollars divided by two million bullets. This is a cost of 0.15 cents (not fifteen cents, but fifteen hundredths of a cent) per bullet. In this kind of operation, properly made tool steel dies might only last 50,000 bullets, at a cost of about $300 for the dies. That is 0.60 cents (sixty hundreds of a cent) per bullet.

Obviously, the value is four times greater for using the carbide dies in this application. One might reasonably expect to make two million bullets on a punch press system: at 40 strokes a minute, and a bullet per stroke, that is only about 104.167 days or about 3.5 months—assuming the punch press is run eight hours a day, which isn't unreasonable.

But even the largest and most successful custom bullet maker seldom turns to punch presses. The average custom bullet operation (if one could ever say these outstanding operations are anything close to "average") turns out about 50,000 bullets a year. After all, the market is limited and the price is fairly high (worth it, but not cheap). You probably wouldn't make even one million bullets in a lifetime of hand swaging. If you could make two bullets a minute, and worked at it every weekend for four hours, you'd only be making 24,960 bullets a year.

When run at less than ten strokes a minute with proper lubrication, the high-carbide content die steels used by Corbin hold acceptable tolerances for at least 500,000 bullets, and some have made over 1,500,000 bullets in commercial operations started years ago. Assuming the dies would make 500,000 bullets, this means your $300 investment in dies would last for over 20 years if you made two bullets a minute, working every weekend for four hours, every week of those years.

If you are just now turning 20 years old, you'd be 40 before you needed to buy another set at that rate. The prices would be different, but the relative prices would be the same between carbide and tool steel. If you expected to live to be 100 years old, you would have a lifetime of bullet making on just three sets of dies, for a total cost of $900. Now, most people don't make anywhere near 24,960 bullets a year unless they are in business to make bullets. The odds are great you'd never make 500,000 bullets in a lifetime. But just suppose you did.

Your cost per bullet for determining die value would be $300 divided by 500,000 bullets, or .06 cents (six hundredths of a cent) per bullet. In your lifetime, if you made 1.5 million bullets, you'd use up three sets of dies, so your total cost per bullet would be $900 divided by 1.5 million bullets, or .06 cents. This is for using tool steel dies.

If you purchased $3000 carbide dies, you would not get one bit more accuracy or any better die, other than the fact that long-term abrasion resistance would be less, so you could get by with one set of dies for your lifetime. We assumed you might live 100 years, and make 1.5 million bullets. Your cost per bullet with a carbide die set would be .20 cents per bullet ($3000 divided by 1.5 million bullets). The steel dies are three and a third times better value for this application! That is 333% more value for your money with the steel dies.

The reason I've gone so long into this is not any animosity toward "carbide", but because of the widely-held perception that just stamping the word "carbide" on a die automatically blesses the product with supernatural powers and makes it somehow more accurate. Hogwash. A die is only as accurate as you can make the hole. It is a lot easier to make a good die from a material that can be worked in its annealed state, then hardened and given its final adjustment in size with diamond lapping in the hard state. The easier a job is to do, the less it has to cost. So, you get more value: the same accuracy for far less money.

Electrochemical machining is a last resort, not a step up. It is used when there is no other practical way to machine a part, because it is very costly, slow and difficult to make the hole precisely the right diameter and shape without going to much higher expense than with traditional machining techniques. ECM has its uses, one of which is to machine carbide materials that simply cannot be cut any other way. There is nothing inherently more accurate about ECM. It costs fortunes in equipment just to make it the same accuracy as lathe boring, reaming, and diamond lapping. Using ECM makes sense when you can't cut the material in a more traditional way. People who sell ECM machines are the first to tell you this.

Unless you are operating a high speed punch press, there is no point and less value in brittle carbide as compared to tough, high-carbide-content die-steel. A person who understands the materials and their actual benefits can make an informed decision. One who simply swallows the advertising hype is set up to spend extra money without getting the extra value. If I thought that there was better value for my clients in selling them $3000 dies, I'd certainly have no reason NOT to do it! But for the past 20 years I've been proving over and over that it isn't necessary and it isn't good value for this application.

Another myth is that aerodynamic shape is synonymous with accuracy. Years ago, I made some bullets that were just cylinders without any ogive at all, and fired them from a benchrest rifle in .224 caliber into a group that measured about 0.2 inches across. Then I fired another group made with 6-caliber ogive spitzer bullets made exactly the same way, with the same weight and diameter and the same materials. These made almost exactly the same size group. The gun was at its limit and the bullet shape had no effect on accuracy, except that the cylinders landed a little lower on the target (more drag, so they dropped slightly more).

In our work for various government agencies, Richard and I made dies that we called the "Ultra Low Drag" or "ULD" design, many years before the popularity of the so-called "VLD" design of the late 1990's. The two designs are quite similar. In fact, nearly all low drag designs that are practical utilize a long ogive and some kind of boattail. Ours used a nine-degree rebated boattail, and a 14-caliber radius curve that was offset by 0.014 inches from the tangent (a secant ogive, in other words). There is nothing magical about the numbers. There are dozens of variations which would work approximately as well, better in some guns, worse in others.

There is a problem with promoting these buzzword designs: people tend to believe that they solve all problems of accuracy, when in reality they are very special designs made for certain kinds of loads, rifling twist rates, and purposes. They are not always more accurate nor are they even useful in some guns. Here are some of the problems with the very low and ultra low drag designs:

u To offer less air resistance, the bullet needs to be more streamlined, which in turn makes it longer for the same weight, or lighter for the same length as a conventional design. To keep the amount of shank in approximate balance with the extra long nose (which would fill up with all the available lead in a normal or light weight design and leave nothing for the shank), these bullets are usually made in the heavier weights for the caliber.

This means that the long, heavy bullet has the center of balance shifted toward the rear, so it wants to turn over more easily than the conventional bullet, and thus requires a higher twist rate to stay nose first. If you have a barrel with the appropriate faster twist, you may get a flatter shooting bullet with equivalent accuracy to a normal design.

Since the custom swaged bullets are usually made with more care than mass produced bullets, you may even get superior accuracy plus a flatter trajectory. But if you don't have a faster twist rate, you may find accuracy actually is worse.

The longer ogive and boattail (or rebated boattail) combine to make the same weight of bullet longer than in a conventional shape, which means that the bullet may not chamber or feed in some guns, and may actually be too long for the throat in the barrel. This might require setting the base of the bullet far down into the cartridge, intruding into the powder space, and possibly requiring the case neck to be partly encircling the start of the ogive. This means the bullet may not be held securely on a center line with the cartridge, but instead might be able to tip and start into the rifling at a slight angle, which does no good for accuracy.

Bullet jackets need to be longer for the same weight, or else you need to sacrifice some weight to use conventional jacket lengths in the extremely long ogive designs. As a practical matter, this might mean making your own jackets from copper tubing or with Corbin's bullet jacket maker kits using flat strip. There is nothing wrong with this, but it runs up your equipment expense as compared to using a conventional shape, and eliminates the possibility of using off-the-shelf jackets for normal and heavy weight bullets.

On the other hand, extremely efficient airframes do give you a flatter shooting bullet, because they drop less in the same amount of flight time. While less trajectory isn't necessarily the same as more accuracy, it contributes to your ability to judge distance and hold the sights in the right place. It helps you be a better shooter, rather than actually improving the accuracy of the bullet, but the effect is the same.

My point is that if you use accuracy and flat shooting as synonyms, you'll be just far enough off the mark so that you'll fall for some of the advertising hype about bullet shape. You may be like the fellow who heard that three of the top benchrest shooters won that year using bullets that happened to have a 7-S ogive (a nose shape formed by a curve that has a radius of seven calibers) instead of the more common 6-S, so he passed up good buys on both 6-S and 8-S ogive die sets to wait for a custom made 7-S set. In truth, any of those sets would have been fine, and the 8-S would be slightly flatter shooting yet.

I'd like to let you in on another secret: there is no inherent difference in accuracy between spire points, truncated conical points, round noses, spitzers, and secant ogives, if you make all of them from equal quality materials with the same level of care. A round nose or what we would call a 3/4-E (elliptical ogive with a length of 0.75 times the caliber) handgun bullet is inherently no less accurate than the regular 9 or 10 degree truncated conical bullet (truncated means cut off, and the TC is a spire shape with the end cut off, usually at about 40% of the caliber). Whichever you like best and feeds best in your gun is the one to use.

There can be a significant difference in accuracy, however, between bullets of different diameter, but there is no cut and dried rule about it except that undersized bullets (compared to the rifling groove-to-groove depth of your particular gun, not to some arbitrary industry standard) generally don't shoot as well as same size ones, and oversized bullets tend to shoot a little better but have minor problems in some guns with case swelling and chambering. The pressure difference is insignificant for a 0.308 inch bullet compared to a 0.309 inch bullet until you reach those loading intensities where the gun is about to come apart anyway.

For my money, if I were to decide on a given diameter for my swage dies, I would always choose either right on the money for diameter compared to my gun's rifling groove-to-groove depth, or slightly larger (between half and one thousandth, depending on whether it is an Auto-loader or not—some pistols have a problem with slightly larger bullets which bulge the case and cause feeding failures). On the other hand, if I had a bullet that shot well in a given gun, I couldn't care less if the bullet was undersized, lopsided and backward! The goal is to hit where you aim, and if the bullet does that, forget about what it ought to be and just be happy that it works so well. Some armchair ballisticians tend to wind themselves up so tightly in their theories that they miss the fun and miss the point of it all: shooting. If it works, it must be right by definition.

Another secret is that many factory barrels are so far different from each other that you wouldn't believe it, and the differences in bore diameter at various points even in the same barrel can be far more than the wildest tolerances in any bullet. Since the whole idea of controlling bullet diameter and tolerance is to make it fit into the bore, or the rifling grooves, there's a problem here!

Why worry about a precise bullet if the bore isn't precise? We've had clients send us sample bullets, pushed through a factory barrel, that came out as much as .41 caliber from a .40 caliber pistol! In one instance, the client sent the gun back twice and got two different oversized barrels, both different by as much as 0.005 inches from each other. I won't mention the gun-maker, but it is a respected name and the problem isn't unique.

This doesn't mean that it isn't important to have good control over bullet diameter. It merely means that you should not take the "published specifications" for granted. Measure your gun if you really want to specify the bullet correctly to fit it. If you don't know how to measure it, you can fire a low velocity slug through it and capture the slug in water, and send us the slug to measure. By low velocity, I mean just enough pressure to get it out of the barrel reliably.

Measuring a barrel is an art. Firing the bullet through it only gives you an idea of the diameter at the point where the bullet came out. Suppose your barrel has "waves" in the bore, where it varys 0.002 inches larger than the average, but the muzzle is actually tight at 0.001 smaller than the standard specifications. The bullet might expand when it passed through the big areas, but it would be drawn down again when it hit the tight spots. Which dimension is really the size of your bore? Who knows—it all depends on your meaning. Average? Mean? Tightest point? Loosest point? Standard deviation?

You want a bullet to fit so it won't be distorted and so powder gas won't escape around it and cut the jacket or lead like a torch. It's worse to have gas jetting around the bullet in the loose places than it is to have the bullet slightly elongated by the tight ones (since the amount of distortion is so tiny, yet the damage by gas cutting can be so harmful to both bore and accuracy). That's why I lean toward large bullets so long as they don't cause any other problems.

What about the pressure ring myth? You've probably heard this one: a good accurate handmade bullet must have a pressure ring slightly larger than the rest of the shank, whereas a factory bullet doesn't have one and that is why factory bullets are less accurate. Lots of shooters believe this one.

Actually, the pressure ring on the back end of a swaged bullet is there for two reasons. The difference in diameter between the core seating die, which is used to make the bullet expand to nearly final diameter in a cylinder form by pressing the lead core into the undersized jacket, and the point forming die, which forms the ogive on the bullet, must be very small, but still the point forming die should be slightly larger than the core seating die (in diameter of hole).

If the core seating die is the same size or larger, the bullet will tend to stick in the point forming die. People who don't know much about swaging will assume the point forming die is bad, when it is likely that the core seater is producing a bullet too large to easily slip into the hole of the point former. The difference is very small. A typical .224 bullet would be made using a core seating die of about 0.2238 inch diameter, or at least the bullet would come out of the core seater at that size (the hole might be slightly different because of material springback).

A desirable range of diameters for a .224 bullet would be from 0.2240 to 0.2245 inches in the parallel shank section. Right at the base, the bullet might measure from 0.2242 to 0.2248. This "pressure ring" is the lack of springback across the solid disk of metal that makes the bullet base, compared to the springy tubular sides of the jacket. Having a large difference between core seater and point former die cavities will make the pressure ring larger, and if the difference gets too large, then the bullet will start to come out with a "wasp-waist" shape, like the old Herter "Super-Sonic Wasp-Waist" bullets of long ago.

(A note about those Herter's bullets: these were most likely reject bullets made because of a severe mismatch in a set of commercial swage dies, but Herter's was innovative enough to turn someone else's rejects into their "Model Perfect" offering of the season. Strange advantages were touted for this bullet: it was said that the air went in a sort of circle around that hourglass shape and somehow whipped around behind the bullet, whacked it in the rear and drove it faster! If this were true, Herter's discovered a perpetual motion machine with a new twist. Imagine what would happen if you accidently gave one of those bullets a thump with your finger while it rested on the table: the air would start accelerating it faster and faster until it was zipping around the room at supersonic speed, blowing holes in all observed physics!)

The pressure ring is not a design feature: it is a physical fact of life that gets in the way of having a nice parallel shank on the bullet and can expand the case neck as the bullet base passes through, leaving the bullet slightly loose. In a short-necked round like the .300 Savage, the pressure ring is a real problem, since the case holds part of the ring and part of the shank, and the bullet flops around as a result.

Most of the time, the pressure ring doesn't hurt anything but if there were a way to get rid of it without hurting accuracy in some other way, it should be done. The best way to minimize it is to match the core seater and point former dies very closely, more closely than you can do with a regular micrometer. You can also make the bullets slightly oversized and tapered, so the dies really eject easily, and then push the bullet through a ring die that irons the sides perfectly straight: now you've got a factory bullet!

That's the way it's done. But that also tends toward a loose fit between jacket and core: the core pushes in and stays there, while the jacket springs back a tiny bit and loosens its grip on the core.

If you bond the core (using Corbin Core Bond flux and melting the lead core into the jacket for a permanent adhesion), you can draw down the shank of the bullet without any springback effect. But all this is not necessary for target shooting and barely necessary for anything else so long as the ring is only slightly 0.001 inch or less) larger than the rest of the shank. If you have any problem with the bullet in a short necked case, then this is worth some consideration.

The main thing is, don't be suckered into thinking that you must have this mysterious feature in order to have a top-quality benchrest bullet. It's just how they come out, no design required or intended, and rather than admit it, many bullet makers in the past have turned it into a "feature". This is rather like the software bug that you call about, and the technical support person claims is actually a feature: it's supposed to work that way, didn't you know? It's designed to crash!

Here's another myth that needs to be shot down: copper fouls your bore, and brass is too hard on it, so you have to use a mysterious metal called "gilding metal" that only the factories have. In the first place, gilding metal is 95% copper and 5% zinc, whereas the brass most people refer to is 70% copper and 30% zinc. Copper is 99.95% copper and a trace of silver or other elements, sometimes phosphorus, sometimes arsenic. You can have any of them for the going price, any time you like. Corbin stocks various kinds of bullet materials and can get others if you order the minimum run.

The factories normally use either gilding metal or commercial bronze for bullet jacket material. Commercial bronze is really not bronze at all. It is another kind of brass, made with 10% zinc and 90% copper. It is cheaper than gilding metal, slightly tougher and can be made harder. Any of these metals can be used to make good jackets. None of them necessarily has to foul the bore any more than the others.

Pure copper, properly annealed, makes a fine jacket material but it is a little more "sticky" in the punch press dies and harder to draw to deep cups, so it is seldom used. A little zinc makes the material easier to draw, but more brittle when it strikes the target. When it comes to a choice between helping the mass producer produce the product, or making the product work better for you, guess which way it goes!

Why do people think copper fouls more than gilding metal, then? I wondered about that for a long time, since we are involved with shooting lots of bullets made with copper and have not noticed any unusual fouling problems. (We get into all kinds of calibers, from .14 to 20mm. We've shot .50's made from everything you can imagine, and fouling isn't any worse with copper.) I think a big part of it is the finish of the material used to make the bullets, and the treatment it gets during the process.

Copper tubing is a traditional material for making bullets. It tends to have a slightly soft, powdery surface after it is annealed. Annealing with gas heat, or in an oxygen atmosphere, will oxidize the surface and cause a reddish or blackish oxide to form. These tend to be flaky and loose. When the copper is drawn down and shaped into a jacket, it will harden slightly but the surface may not be burnished enough to get rid of the porous layer. I think this layer is what comes off in the bores.

Nearly all metals will leave something of themselves in the bore, but we are talking about fouling bad enough so that it is a problem, an exceptional amount of fouling. And with properly drawn and polished bullets, I have not seen any significant problem. With the highly finished copper strip that we use for making drawn bullet jackets, there is no problem worth consideration.

Some of the rumor probably comes from the fact that people who do this sort of experimental work with bullets are more curious and inspect their guns more carefully than people who just buy factory bullets, and they notice even a small amount of fouling sooner. Some of it comes from the loose, porous finish that experimenters may get on their torch-annealed copper tubing jackets. So, use annealed copper instead of annealing it with a torch, or polish the jackets so that the outer surface is removed down to the hard underlying metal. Don't worry about it unless you actually experience a problem, which you probably won't.

There certainly are a lot of myths to debunk! I don't think this book is big enough to handle all of them, but those are a few of the important ones that might keep you from trying something that would actually help you. I think one of the most important myths is really a whole grab-bag full of related ones about strange, mysterious things you might have to do in order to get your bullets to shoot accurately. I've heard all these tales about how you have to let the bullets "rest" overnight before you shoot them, or how you have to swage cores and then put them in a jar and give them a day to "normalize" (whatever that means) before putting them into the jackets.

Most of this is purely in the mind of the person who believes it, and came about either because someone else said it, or because the person happened to shoot a great group one day after doing something of the kind and from that day forth will always give the ritual credit. I wonder if a hunter who dropped his rifle and had it go off and by sheer luck shot a deer with that stray bullet would henceforth go into the woods and toss his loaded rifle on a rock?

I suppose we all know people who got lucky one time with totally inappropriate equipment or techniques, and without any further testing just assumed that the thing they did incorrectly was responsible for the good fortune of that day. Likewise, bad results are sometimes blamed on coincidental precursors. A statistic says that 80% of all people killed in car wrecks ate carrots during the previous twelve months. So, does this mean that eating carrots causes you to get killed in a car crash? If you don't eat carrots, do you thus avoid such a fate? Oh, my, it's time for a refresher course, Logic 101.

Once Friday I made a pile of bullets and wanted to shoot a good group so much that I spend all afternoon weighing and sorting them into two piles. The first pile had almost no weight variation that I could measure: those suckers were right on. The other pile had the other bullets, which could vary as much as three grains plus or minus from my desired weight. After supper, I went back out to the bench and I carefully loaded them up for my heavy barrel .222 Remington on a nice Sako action, weighing every charge, and seating those bullets with the greatest of care. I was ready for Saturday's match.

Saturday was a great success, and my group was as small as I could have hoped. I was now positive that absolute bullet weight control was the secret of small groups. Upon my triumphant return home, the first thing I noticed was the pile of bullets on my loading bench. It looked suspiciously small. Weighing a few, then a few more, it finally dawned upon me that I had loaded the rejects and shot them, instead of the selected ones. Come to think of it, there were a lot of loaded rounds! So I guess a six grain range of weight variation didn't make all that much difference in group size, after all.

One more myth: the correlation between bullet weight variation and bullet "quality", which generally means potential accuracy. This one is partly true and partly misunderstanding. If a bullet is unbalanced, so that one side is heavier than the other, it will tend to spiral in flight and will land at different points around its axis of flight. That much is well proven and has been known for years. If the difference in weight between two bullets is caused by a bullet jacket that is thicker on one side (eccentric jacket walls) or if it is caused by an air pocket or void within the core of one bullet which is off-center, then the weight variation is a way of telling us about eccentric construction.

Note that we don't know which of the two bullets is built incorrectly. With air pockets, the lighter bullet is probably the bad one, but with eccentric jacket walls, we don't really know if the heavy bullet has a thicker wall on one side, or if the lighter one has a thinner wall on one side. If the lighter bullet has a thinner wall but it is concentric, then provided we had five more like it, we could shoot just as good a group as we could with a concentric, thicker-wall jacket. If we had bullets with air pockets that were perfectly centered, such as you get with a hollow base or hollow point that is correctly swaged, then there is also no problem with eccentric weight or balance.

Mixing bullets that have eccentric weight variations into a group that has none will increase the group size. Mixing thin walled concentric jackets with thicker ones can change the group size only because the friction of the jackets as they pass through the bore may be different, so the powder burns a little differently, and the velocity may vary. This can cause the bullets to drop more or less depending on their velocity. The variation due only to difference in weight, meaning the gravitational drop, is so slight at 100 yards on a few grains (such as 2% or so of the bullet's weight) that you can disregard it. You may as well talk about the effects of an airplane flying over and its gravitational pull shifting the bullet impact as the weight variation in a 2% or less situation.

If you make your own bullets, and you have jackets that not only weigh the same but have walls that are the same on all sides, and you seat the lead cores to the same pressure so there is no loose core and no air pockets, then you will be able to ignore weight variations of less than 1% of total weight for any kind of shooting, and below 2% for anything but top level benchrest competition. Any weight variation in this range would be simply more or less core, concentric to the bullet center line, and would have no serious or noticeable effect on group size.

If you have the same weight variation and it can be shown that the cause is eccentric walls or anything else that causes the weight to be shifted in an eccentric manner, then you will probably notice an increase in group size. So, weight variation is not an absolute measure of quality, but it is an indicator of a possible problem. One of the gunsmith/die-makers on the Corbin team has built an accurate .22 Hornet rifle for testing this in a quantitative manner. He has loaded bullets to serve as control for the average groups, and will be conducting a long series of experiments to see just how much weight variation of both eccentric and concentric type is required to affect the group size.

(Eccentric bullets are easy to make by putting a known weight of nylon string down one side of the jacket before swaging in the core—you can control the weight and position of the variation this way.) I suspect we will find the groups of bullets made with concentric weight variation (more or less core weight) are within the average size for the control bullets, whereas the eccentrics tend to fall outside in proportion to the amount of eccentricity, but we'll get some hard facts and numbers and then write about it later.

My point is that weight is not some absolute number that tells you "good" or "bad" about a bullet. After all, a 2 grain plus or minus variation on a 50 grain .224 is plus or minus 4% of the total weight and may have some noticeable effect, whereas the same variation on a 500 grain .458 bullet is only 0.4% and is below the limit of accuracy of most electronic meters and chronographs, and is unlikely to have any affect that can be measured.

As a rule of thumb, strive for a maximum of 1% plus or minus weight variation in your best target bullets, and don't worry if you make hunting or defense bullets with a 2% variation. To get this figure, divide the difference between the heaviest bullet and the lightest bullet by the average bullet weight, and multiply by 100. The average bullet weight is the total of all weights divided by the number of bullets that you weighed.

One last example is the myth of the infallible micrometer. I think that at least once a month we hear from someone with the world's most accurate micrometer. That remarkable tool certainly gets around. Since the advent of digital electronic readouts of reasonable price, and the availability of micrometers and calipers with stated accuracy of either 0.0005 or 0.0001 inches (or sometimes 50 millionths, or whatever the ad writers feel like writing that week) there have been more than a few people who call to note that they expect to order a bullet that measures some ridiculously precise figure and wonder if we'll guarantee it.

In the first place, Corbin probably makes the most precise bullet swages you can buy because we have put literally decades into building the only full-time, full-line bullet swaging equipment and die-works in the world, and you can't run one without the best measuring instruments. Each of our diamond lapping machines has a gauge mounted on it that cost several thousands of dollars, and is tested and set with a setting fixture that is periodically sent in for NBS calibration. The setting fixture alone costs more than most people would pay for their second car. The diamond probes that fit into the precision bore gauges cost several hundred dollars, and each one only covers a narrow range such as .204 to .210 inches, so we have thousands more in all these little diamond probe sets.

I am not reciting all this to impress anyone with what we spend on measuring tools, so much as to make this point: if there were anything better, we'd buy it. That's our business. We have to know the limits and uses of precision measuring tools to survive. Those salesmen who call on Corbin certainly are more than anxious to sell us the latest and best technology, and they keep us appraised of it. Precision measurement isn't something we only read about in an old copy of Machine Tool magazine at the dentist's office.

I also don't mean to imply that we know it all and no one could possibly measure anything better: we make errors like anyone else. I'm sure that at NASA or Sandia Labs or Cal-Tech there are tools of greater precision than we can justify or afford. But what I do mean to point out is that someone with a digital micrometer that costs a hundred bucks or so isn't even close to the state of the art in measurement precision, and if this high priced equipment we use is only guaranteed to give plus or minus 50 millionths of an inch precision, you can darn well bet that the micrometer isn't going to actually give you anything like an absolute precision of plus or minus a half thousandth inch, which is 500 millionths.

So, how can the ads in the machine tool catalogs say that the readout is accurate to 0.00001 inches or whatever they claim? Easy: they are talking about the readout. The digital readout is the thing that displays the numbers. If it says a given number, you can bet it means exactly that number, to the last digit it can display plus or minus one digit (since any digital tool has no finer division than 0 or 1 on its last number displayed, you never know for sure if the last number is half way between 0 and 1).

But the trick—the secret, if you will—is in that wording. The readout accuracy has nothing to do with the instrument accuracy. You can connect a digital readout to anything, and the numbers will click off just fine, but they mean nothing more than the mechanical limit permitted by the actual instrument itself. You could put a ten decimal place readout on your car odometer, but the wide tolerance in the little gears and cabling to the engine or transmission would limit the usefulness to whatever mileage reading you normally get without all the decimals.

Digital readout on a moderately priced instrument is a way to fool gullible buyers into thinking they bought the world's most accurate tool for a few dollars, while the "uninformed" laboratories continue to spend thousands to get the same kind of accuracy. It's the stuff headlines in supermarket checkout magazines are built from: "Man Survives Fall From Space Shuttle: Doctors Baffled". It's human nature to want to think that all the experts are wrong, because it gives the average fellow's ego a little boost. Sometimes the experts are wrong, of course. But, really, if it were possible to get dependable accuracy in the tenths of a thousandth inch with cheap tools, why would anyone in business waste money on anything else?

I will never convince the person who is so proud of his new digital mike that he can't repeatedly and accurately tell what the diameter of a bullet is to five places, and probably not to four. The limit of accuracy of a lead-screw micrometer, which nearly all of them are unless you buy laser or magnetic track instruments (for thousands of dollars) is the physical accuracy of the mechanical screw thread itself, not the digital readout. This cannot honestly be guaranteed to be better than 0.0005 inches in the very finest of instruments, (such as the Starrett "Last Word" bench mike) and more likely is only accurate to 0.001 inches. Of course they read to zillionths of an inch (well, at least 0.0001 inches) but being able to display a tiny number does not mean the tool really sees it repeatedly or even sees it at all.

For all practical purposes, a micrometer you can hold in your hand will give you the nearest thousandth plus or minus about half a thousandth. So if you specify a bullet of 0.308 inches plus or minus 0.0005 inches, you have some chance of telling it is between 0.3085 and 0.3075 inches. If you buy a gauge block with guaranteed traceable dimension of 0.3080 inches plus or minus 0.0001 inches, you can set your mike as a comparator to see if your bullet is .3081 to .3079 inches.

But you can't tell if you have a .30805 or a .30795 inch bullet. A screw thread measuring system just won't repeat any closer than that. All it can do is give you a readout where the numbers themselves are guaranteed to be whatever the ad says, not that they represent what the measured part actually is. That is how many precision tool brands are sold to the public today. The difference between readout and instrument precision is just complex enough so that some people don't care to understand it. It's much easier to believe you bought the precision of a $5,000 lab tool for $150.

What matters is that the bullets land in the same hole, or as close to it as possible, and there is no way yet devised to determine if they will do that before shooting them! Bullets that are undersized to the bore by even half a thousandth may show signs of lower accuracy, whereas bullets that are a thousandth oversized from this ideal usually shoot as well as the "right" size bullet.

But we don't really know in advance what is "right" because it depends on your particular barrel. We do know that in general, if you want maximum accuracy, you should strive for a tolerance range of minus zero, plus one thousandths of an inch from the groove-to-groove depth. You may not find this is "right" for every gun or load, but it is a good starting point.

Chapter 4. Tubing Jackets

Besides the swaging dies to make bullets, there are also jacket making dies. You can buy ready-made jackets (the cups or empty skins for the bullets are usually made from a copper alloy, from 100% copper to 80% copper and the rest zinc). Bullet jackets are from .001 to .005 inches smaller than the caliber, so they can be expanded upward when you insert and seat the lead core. You can't always buy the calibers, lengths, and thicknesses you want to use. There are good alternatives to buying them. You can make your own, or you can buy something that is available and draw it down to make a smaller diameter, greater or less length (by pinch trimming), and thinner or thicker wall (by design of the punch to die clearance).

Commercially made bullet jackets normally contain from 5% to 10% zinc, with the balance of the alloy being copper. The 5% zinc alloy is called "gilding metal", and the 10% zinc alloy is called "commercial bronze", even though it isn't a bronze at all (bronzes are tin-copper alloys). The advantage of the zinc is that it makes the jackets easier to draw into deep tubes, starting with flat strip, without breaking through at the end or wrinkling. But for shooting purposes, pure copper tends to hold together better on impact and has about the same level of fouling if the surface finish is equally good.

Corbin makes two different systems to form your own bullet jackets, one system using tubing, and one using flat strip. Tubing dies cost less and fit more kinds of presses, but strip jackets have the accuracy edge and can be made with greater control over the wall tapers and thickness.

For big game hunting, the tubing jacket may have the edge since it is easier to build thicker walled, tougher jackets with tubing (after all, the deep drawing operation is done for you in tubing and all you have to do is round over one end and adjust the diameter in a draw die). Jacket drawing from strip can be done in a hand press only for jacket lengths of about half an inch (or less), because punching out a disk and turning it into a cup requires a lot of power early in the stroke. Hand presses generate almost all their power at the end of the stroke. Hydraulic presses are used for draws that exceed the half inch jacket length, in order to get full power at the start of the stroke.

Copper Tubing Jacket Maker Sets (CTJM-1-M, -S, and -H)

You can make jackets from copper tubing (or almost any other metal, but copper, aluminum, brass, and mild steel are the most practical things to use, and of these, copper works best for most shooting needs). To do this, you could use copper water tubing (yes, the same kind used to hook up wash basins), boiler tubing, or refrigeration tubing. Corbin has precision drawing grade tubing available also, if you want "good stuff" for testing.

The cost of new tubing generally means that you won't save money over buying jackets if the jacket you want is already available on the market. But most large caliber jackets for rifles, or heavy walled jackets of any sort, are simply not available unless you make them, so the cost of the jacket is secondary to whether or not you want a better bullet! Prices of from seven to twenty cents for material, depending of course on the source, quality, size, and length you need, would be a good range in 1996 as this is being written. Of course, if you can get a reasonably good quality of tubing surplus, from contractors or plumbers, and the wall thickness variation is not too bad, you might get by very cheaply indeed.

Regardless of the size or type, you would cut it to length, deburr one end, put the piece over a precision punch and round the end over in one of our end-rounding dies (looks like a blunt point forming die), anneal the tube, draw it to smaller diameter, and then flatten the end with a special punch in your normal core seat die.

The advantages are (1) tooling is quite reasonable in price, (2) the number of operations is relatively small and not hard to learn, (3) tubing is fairly low cost and you might get even lower priced deals from building contractors just finishing up a big apartment complex, (4) the process makes very tough bullets for big game shooting. And there may not be any practical alternative, if you need a high performance hunting bullet.

In a Corbin hydraulic-powered press such as the CHP-1 Hydro-press, or CSP-2H Hydraulic Mega-Mite press, using the H family of high pressure dies, you can completely close the base so no hole appears. In the -M and -S family of hand press dies, which fit the Corbin Silver Press CSP-3, or the Series II Press, CSP-1, or when using an -H die in the Mega-Mite CSP-2 hand press, you cannot generate enough pressure to completely close the base, so a tiny hole remains, but it is far smaller than most military open base bullets, so it causes no problem.

Tubing jackets are not just pieces of tube shaped into a bullet: they are almost identical to a normal closed-base jacket. Generally, they have thicker walls with no taper toward the front. You can make almost any reasonable length and wall thickness, if you use the correct press and dies.

Partitioned jackets can be made, in either the CSP-2H Hydraulic Mega-Mite or the CSP-1 Hydro-press: the tubing is compressed between two punch shoulders while supported internally by smaller diameter punch tips, leaving only a short space between the punches for the jacket to fold inward and create a double-thick partition. I don't recommend it if you can use Corbin Core Bond instead, which is inexpensive, fast, and works much better in actual big game hunting than a conventional partition design.

The disadvantages of tubing jackets are:

(1) the walls tend to be straight, rather than tapered, so that without special operations the jacket will not be the "controlled expansion" type...

(2) tubing jackets generally are not practical to make below .030 wall thickness (sometimes you can get .025 wall tubing, but it is harder to find and doesn't always form, in every caliber or shape, without buckling), and...

(3) it is not practical to build precision benchrest grade bullets using readily available tubing. This is not to say tubing jackets are "inaccurate", but only that a deep drawn jacket can be made with closer tolerances given the materials available on the market today. Tubing jacket bullets can, and have, set match records. But they probably will never set high level competitive benchrest records. On the other hand, they certainly do bring home a lot of big game every year where the thinner and more brittle drawn jackets fail and let it get away!

Four types of Copper Tubing Jacket Maker sets:

CTJM-1-M (Copper Tubing Jacket Maker, type -M) uses 3/4 inch diameter dies, and fits either the Silver Press (CSP-3) or the Series II press (CSP-1). This set can make jackets up to 1.2 inches long, although you must move the punch holder back and forth to load longer pieces and form them. The wall thickness is limited to 0.035 inches (the standard type L copper tubing normally has 0.032 inch thick walls). Only copper tubing is recommended. Jackets can be made from .25 to .458 caliber in this die family. In theory, you could also make smaller calibers from tubing, but it is cheaper and easier to make them from fired .22 cases. At this time, tubing is available from over 200 primary sources in the USA alone, but almost all the available sizes are 1/2 inch O.D., 3/8 inch O.D. and 1/4 inch O.D. without paying for costly custom drawn production runs. These can be used to make all calibers in the range mentioned (as well as calibers up to .512, but not in -M type dies).

CTJM-1-S (Copper Tubing Jacket Maker, type -S) uses 1 inch diameter dies, and fits the Series II (CSP-1) swaging press, or the Hydro-Mite Hydraulic Bench Press. This set can make jackets up to 1.2 inches long, and may require some moving back and forth of the punch holder to load the parts. The same wall thickness and diameter limits apply, but the dies are stronger and less likely to be broken if you apply more than the required force. Although I don't recommend or guarantee it, some clients have had good success with brass and aluminum and even mild steel tubing in the -S dies. Proceed at your own risk, though.

CTJM-1-H (Copper Tubing Jacket Maker, type -H) uses 1.5 inch diameter dies, and fits the CSP-2 Mega-Mite press, the CSP-2H Hydraulic Mega-Mite, and the CHP-1 Corbin Hydro-Press. There is almost no limit to the kind, thickness, and length of material you can form in these dies. Mild steel, copper, brass, aluminum—all are candidates for a set of tooling to make good jackets. However, you cannot interchange them with abandon. A set of dies developed for the characteristics of one metal, one wall thickness and diameter of tubing will not necessarily work with different material or dimensions.

CTJM-2-H (Partition Tubing Jacket Maker, type -H). If you should wish to make a partitioned or H-sectioned bullet, this is an option to consider. Bonding the core will actually give superior performance, in regard to retained weight. But the fame of the Nosler Partition Bullet* and the earlier German H-Mantle design has made people aware of the genre. That alone is enough reason for us to offer tooling to make it.

The process is quite simple. It is only possible with the power of the Hydro-press, or the Hydraulic Mega-Mite press. Two punches fit into the cut tubing, one from either end. Both have a reduced diameter tip section that just fits inside the tube to support it internally, and of course the die wall supports it externally. But the length of the punch tips combined is just short of the specified tube length.

When you place the tube in the die, and the punches begin pressing on either end with their narrow shoulders (which can only be the wall thickness of the tube), the tube material is supported everywhere except in the middle, between the punch ends (because there is a gap between them). The tube folds inward upon itself, and the punch ends come together on both sides of the fold and compress it into a pressure-welded band.

After this is done, two short cores are made, one for either end. The tube is drawn to the right diameter in a draw die, and then put into the core seating die. A special core seating punch with a probe tip supports the partition from inside, while you seat one of the cores in the opposite side. Then you turn the tube over, change to a new punch with a shorter probe section (just barely inside the jacket, where the core comes almost but not quite to the end of the jacket).

A second core is then put into the remaining end, and a normal core seating punch presses it in place. This punch is the same one that seated the other core. So, you can see that there would be two core seating punches, normally both of the internal type, and only one external core seating punch. The bullet, at this point, is a cylinder with lead in both ends, one lead core being just below the jacket end and the other can be just about anywhere in relation to the jacket. The core just below the jacket edge will be the base section.

To close the base, you would put the bullet into the point forming die backward (base first). Using the core seating punch, you would press on the nose section to force a small curve on the base, just in the length of jacket that protrudes pas the core. Then, you would turn the bullet over, putting it nose section first into the point forming die, and changing external punch to a full-diameter point form punch. This punch presses on the curved base edge and flattens it, while the nose is shaped in the curve of the point form die.

You would normally make a run of each operation, then change punches to continue with processing all the jackets through the next stage. I explained it as if you were only going to make one bullet. It's a good idea to make one bullet, before you start a run.

You then know what the end result will be before you make hundreds of components. If you don't take the time to finish one, you have only yourself to blame if your big pile of almost-done bullets turns out to have too small a core or too large a tip, or too much lead to let the base roll around and flatten properly. It is still much faster than casting, and a great deal more safe.

It isn't necessary, nor is it practical, to form a totally solid wall between the two chambers of the jacket. Normally, there will be a hole left in the partition. The jacket will be nearly doubled in thickness from the folding upon itself, and the hole may be only one eighth of an inch or so in diameter. If you want to make a totally closed partition, you can put a small copper rivet or a copper disk inside and flatten it in the hole with the core seating and partition supporting punches.

This design of bullet still has some slight flexibility so it is no harder on your barrel than any other bullet made of the same material. Don't worry about the partitioned area being a solid copper band that may increase pressure compared to the thinner walled jacketed bullets. It isn't, and it won't.

Having told you all about the partition jacket maker, now I will tell you that if it were my decision, I would save my money and not buy it, and would instead make "bonded core" bullets, which outperform the partition design by a wide margin! All you have to do to bond the core to the jacket so it cannot separate (which is the whole purpose of the partition) is to swage a core that drops into the jacket with a slightly loose fit, put a drop of Corbin Core Bond liquid in the jacket along with the core, and heat the jacket with a propane torch or in a furnace until the lead melts. Let the bullet cool, wash it in baking soda and hot water to clean and remove the last bit of core bond material, and then seat the core as usual. Your bonded core bullet will outperform any partitioned bullet, and you save money and time building it.

A tip you can use: to keep molten lead from running out the hole in a tubing jacket, get a block of potter's clay and push the jackets down into it to hold them upright (only enough to support them, not even a quarter of their length). Drop in the core, which must fit easily by hand or it is too large. Put in a drop or two of Core Bond, and heat the jacket with a propane torch until the lead melts. The clay will probably harden into a little plug in the bullet's base hole and seal it, but in any case it keeps the lead from running out. You can squash the block again and use it until all the clay is gone or turned hard. You could also wipe a plug of clay into the base holes and then use something else to support the jacket. Leaving the tiny dot of clay in the base is not a problem. It weighs next to nothing and looks interesting.

Changing lengths and tubing dimensions

You can change the length of a tubing jacket, if you also purchase two additional punches per length. The two punches are (1) the end rounding punch, which has a turned-down section that is just shorter than the desired length by half the diameter of the tubing, so that enough metal protrudes to be rolled over into a base within the first die, and (2) the end flattening punch, which likewise has a probe-like section that fits inside the rounded, drawn and annealed tube just far enough to compress the rounded end and make it flat, within your existing (not part of the set) core seating die. Sometimes you can use the same end flattening punch, depending on the amount of change in length. The whole idea of these punches is that enough unsupported tubing projects past their end to roll over into an angle or curve (in the end rounding die) and then flatten by pressing firmly in the core seating die (without a core).

If your jacket projects a little more past the end than the sample sent with the punch, it will probably work anyway, until it gets long enough so that a lot of jacket is unsupported and collapses inward on itself when you try to round the open end. But if the jacket is even a little too short, the punch will come up against the end of the die and there won't be any jacket there to be rounded. Thus, you have wider base openings, incomplete closures, and might even damage the die or punch trying to get the base to close up.

The right length to cut the piece of tubing is about a quarter inch or so longer than the length of the smaller diameter of the punch (so it projects that far past the punch tip). Another way to look at it is to make the tubing about half a caliber longer than the punch tip length, since you are going to fold it over half a caliber per side to close up the base. The length of the cut tubing is marked on the punch. Length is critical to within about 0.01 inches for a given punch.

Selecting the right tubing

The standard sizes of tubing that are available, and which we stock for resale, are 1/2 inch O.D. and 3/8 inch O.D. We can also make custom diameters. Three other useful diameters are 7/16 inch O.D., 5/16 inch O.D., and 1/4 inch O.D. They are more difficult to find than the first two, but we can draw them for you.

In each case, the closest larger diameter of tubing is selected as the starting point for a caliber you want to make. The 1/2 inch tubing is used to make all calibers from .512 down to just above .375 (for instance, the .400 caliber). Both rifle and handgun calibers can be made, although you need two punches for each length. You can't make jackets shorter than the punch design without striking the punch end against the bottom of the die, which fails to fold the jacket over to make a base. Longer tubing will tend to buckle.

The wall thickness of standard tubing is 0.032, 0.035, 0.049, and 0.065 inches, depending also on the diameter. Some diameters are simply not available in a given thickness of wall without custom mill runs (translates into a big order and lots of money). If you want anything else, it may be available if you can buy a mill run. We can not make jacket maker sets without having the tubing you plan to use. Each jacket maker is a complete development effort, trial and error, to make sure it does the job right. We can not do it "by the numbers" because tubing tolerances are not that close and our die and punch tolerances are extremely tight. We have to have some material on hand to work with.

If you plan to use our standard tubing, then there's no problem. If you plan to get your own tubing somewhere else, we must have at least six feet of it on hand before we can start your order. We will cut it into pieces and test the tooling. The length and diameter, whether the tubing sticks or releases from the punches, the concentricity and evenness all depend on the temper, grain, alloy, tolerances, wall thickness, and diameter of your tubing.

Plumbing is not especially precise in these factors. If you get a large quantity at one time, it will probably be consistent enough to make good bullets, but if you change suppliers there is no guarantee that the same nominal sizes you get will be anywhere near identical. The jacket maker punches may need some adjustment, or different punches need to be made, in case you change vendors or your vendor changes specifications.

Corbin's tubing is higher cost than some of the tubing you will find in the hardware stores, but not by a great deal. We are very strict with our specifications and order large lots of high quality tubing just for bullet making. We recommend that, unless you have a good source of tubing in mind, you use our standard tubing to get started. We can help you obtain larger quantities when your needs outgrow a few dozen feet at a time, but until then, the odds are good that you won't find much better pricing.

My recommendation is that you establish prices for your custom bullets that allow you to make a profit even with the higher cost material, purchased initially in small quantity. Then, by the time you can afford the larger mill orders, you'll have already guaranteed a higher margin and your success will be just that much greater.

The range of calibers for each size of tubing

• 7/8: .787 down to .750 such as 20mm and similar slugs.
• 3/4: .75 down to .626, such as 12-gauge jacketed bullets.
• 5/8: .625 down to .515, such as .600 Nitro, .577 Snyder.
• 1/2: .510 and .458 down to .400 diameter.
• 3/8: .375 down to .318. Best in .375, .358.
• 5/16: .314 down to .264 caliber. Best for .308.
• 1/4: .257 down to .224 (but free .22 cases are available)
  

You need to know how to cut tubing to length without wasting too much effort, or damaging the ends with burrs and crimps. A tubing cutter usually rolls the end so much it won't fit over a punch. Use either a lathe, or a metal cutting blade in a saw. Some of the more successful methods include a fine tooth metal cutting blade in a chop saw, table saw, miter box saw, jig saw, or band saw. A home-built stop, consisting of nothing more elaborate than a block of wood clamped to the saw table, will give you reasonably accurate lengths.

The number of teeth per inch should be from 32 to 40 on a hacksaw blade. The rule of thumb is "three teeth in the material at all times". Copper is a little "sticky" so you may wish to use a blade with a special tooth set or with a reverse rake on the teeth. We use a turret lathe and an air feed. We can chop up accurate lengths with one end deburred in runs of 500 or more.

We also have tubing in 2 foot lengths, easy to mail or ship anywhere in the world. You can save some labor cost by chopping these up yourself. Tubing normally comes in either 20 foot pieces in big boxes of 200 to 500 pounds each, or in coils (annealed tubing). We use hard drawn or 3/4-hard, as it is called, because it is easy to handle in a lathe for cutting.

You must anneal the tube after you have formed the rounded end and before drawing it down to correct diameter. If you fail to heat the jacket red hot and let it cool (annealing it), then you will have problems with cracking, sticking on punches, uneven or difficult forming. A regular propane torch is all it takes. Just sit a few jackets on a couple of fire bricks, arranged in an "L" shape so the flame is reflected back, and heat them by playing the flame directly on the jackets, one by one.

A great many of the problems that some bullet makers have with tubing jackets and bullets comes from skipping the annealing stage. For whatever reason—maybe because it takes extra work—they assume the step is unnecessary. Wrong! Skip it and you will have problems with tubing that sticks in the dies or on the punches, bullets coming out the wrong diameter, or bullets that come out the wrong length! Maybe you will get away witho