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What Is Bullet Swaging?

To "Swage" is to form projectiles -- bullets, not loaded cartridges -- using high pressure at room temperature to flow materials in the cavity of a diamond-lapped, high precision die.
No heat is used. Materials to be swaged move like putty under 10,000 to 50,000 psi pressure to take on the size, finish, and shape of the die cavity.

Swage is pronounced like "wage" or "stage". It is not "swag" like "rag" or "bag". A swag is curtain fabric draped in a loop, items stolen by a thief, or party gifts, not a process.

Swaging is the opposite of drawing. When you DRAW a bullet or jacket, you push it through an open ring die that reduces the size. When you SWAGE a bullet, you expand it to a slightly larger size in a pressure-sealed die. You can draw down, but you always swage up.

Pressure in the 10,000 to 50,000 psi range is applied with a powerful high precision press. The pressure is applied through hardened, high strength punches which compress the material inside the diamond-lapped die. This causes expansion in diameter to the exact shape and size of the die cavity and punch ends, transferring the precision finish of the die and punch to the bullet.

The process can be used to make lead or jacketed bullets, even lead-free bullets from ductile mixes or powders, in virtually any caliber and shape. Pellets, shotgun slugs, pistol and rifle bullets, round balls for muzzle loaders -- nearly any kind of bullet -- can be swaged in one or more steps, depending on the design. For more than 50 years, Corbin has been the world's foremost manufacturer of bullet swaging equipment, supplies, and information.

Bullets can be made of one material such as solid lead, copper or a powdered metal mixture, or they may be "jacketed", meaning the core material is covered by a "skin" normally made of relatively thin copper or brass alloy. The "jacket" can be purchased from Corbin, or made at home from copper tubing or from flat copper strip, with Corbin jacket-making tools.

Jackets are always slightly smaller than finished bullet diameter, and are expanded by the high internal pressure applied in "seating" the core. Jackets are not "put on" a bullet. They are expanded and formed with internal pressure against the ductile core material, until they are stopped by the diamond-lapped die walls. They take on the shape, diameter, and even the finish of the die surface.

Jackets protect the core material from excess friction, deformation from gas pressure in the barrel, and control performance on impact. They also protect the bore from fouling or melting of the core material from friction and heat. Both jacketed and non-jacketed bullets can be swaged easily with Corbin tools. In many cases, the same tools are used for either style, perhaps with slightly different punches.

The "BULLET" is the part of a cartridge which is propelled through the air to the target.

Bullets are not the entire cartridge, which consists of a bullet, a cartridge case or casing, gun powder, and a primer to ignite the powder. It is very important to use the right terminology and to understand that although many people say "bullet" when they mean "cartridge" or "Loaded round", the bullet is ONLY the inert piece of metal which becomes a projectile when the gun is fired. Corbin specializes in making the bullet swaging tools and does not make cartridge forming tools.


There are three ways to make bullets:



Casting


is the oldest method, as well as the one that most hobby reloaders use. Casting uses a lead furnace to melt the bullet alloys, mould handles, a mould for each weight, shape, and caliber of bullet, then a sizer and lubricator device to correct the diameter and apply a thick bullet lubricant.


Machining


from solid materials requires a large investment in precision machine tools but can be more precise than casting. It is slow, and subject to tool wear, chatter, and machine variables and is used only by a few custom bullet firms, or to turn a prototype bullet. Solid metals like copper, brass, and iron are better machined than cast or swaged into bullets, with few rare exceptions.


Swaging


uses materials which can be pressure-formed at room temperature. These can include solid or jacketed lead, plastic and powdered metals. The tools are a high pressure press that can flow the bullet materials without melting them, and diamond-lapped, high precision dies with matching punches that instantly give the materials their final dimensions (shape, caliber and even internal constructions) with no further processing, lubricating, or sizing.

Both casting and swaging are simple processes. Swaging is the most precise method of making a bullet. It is safe, fast, versatile, relatively easy to learn, and has many technical advantages over casting.



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Five Problems with Casting

The problems with castings are:

  1. The process itself involves extremely hot molten metal, which is viewed by some as a toxic process. But the main danger is from burns and lead pot explosions: a drop of water, a fly or moth that suddenly drops into the pot, can cause the entire content to fly into the air with an explosive force. Casting bears certain risks that are not present with the cold metal forming technology of swaging.

  2. There is little flexibility to experiment with bullet shapes because each shape, caliber, or weight requires an investment in a new mould. The only way you can get custom shapes is to pay for a custom shaped mould. In contrast, swaging offers almost unlimited weights and dozens of styles in a single swage die, based on technique alone. As you add more punches and dies, the possibilities multiply: you can combine steps on a single bullet to produce shapes none of the parts would have made by themselves.

  3. With casting, the time it takes to melt lead, heat the moulds, cast, inspect, reject culls, sort, size and lubricate, then allow for cooling and cleaning up makes it difficult to try a few bullets on a moments notice. Swaging can be done in seconds starting with a roll of lead wire and a swage die. The finished bullet pops out of the die ready to shoot, no sizing or lubricating, no hot tools to cool and put away.

  4. The basic design of any cast bullet is a frozen piece of lead, eliminating the possibility of jackets, partitions, shot-filled cups, multi-part bullets, bonded cores, hollow-base/hollow point combos, and thousands of other innovative designs, whereas swaging allows all of these exciting designs and more.

  5. Inaccuracies result as trapped air or other gases cause unwanted internal bubbles, with changes in weight and balance. High temperature molten lead goes to room temperature on every bullet cast, so that thermal size variation is a built-in factor. Mold halves swing together on a pivot, which introduces play and misalignment. In contrast, swaging works with precise round holes in solid dies, which do not have to be heated and cooled for every bullet. The pressures used are often 2000 times that which is placed on cast lead, eliminating voids and trapped air.

Why Major Ammo Makers Swage Their Bullets


The method used by the major ammunition companies, benchrest bullet makers, and virtually everyone who is interested in making the most accurate bullet possible, is swaging, or pressure-forming. Unlike casting, swaging does not involve heating molten metal, so it simply doesn't have the same toxicity or danger of burns or fire. Likewise it does not experience the same heat induced changes in dimensions, the wear and eventual misalignment of split molds, or the out-of-roundness that results when a split mold is opened to and closed, exposing the surfaces to room temperature air and then immediately to 450-degree molten lead.

Swaging is a very flexible process, allowing one to make multiple variations on a theme with a single set of dies. A single swage die is equivalent to thousands of moulds, since it can make virtually any weight of bullet in a specific diameter. You can even make your own jackets from common materials such as copper tubing, copper strip, or fired .22 cases, and produce bullets that outshoot anything you could buy off the shelf (since you can control the bullet weight, shape, and style precisely for the best result in your particular firearm).

Swaging is much better suited to high-volume manufacturing with virtually no variation from bullet to bullet. Notice that bullet manufacturers from Sierra to Winchester makes their bullets using the swaging method. Recent Speer ads make the point clearly by specifically pointing out precision swaging as the method of production. Of course, swaging has long been the only viable choice for anyone in the commercial jacketed bullet field, with the exception of electro-plated lead bullets or CNC turned copper or brass rod bullets (and many of them are then re-swaged in Corbin dies to regain their precision diameter and finish).


Corbin Swage Tools Work For You,Too!


For years, many hand loaders were under the impression that swaging was too expensive or complicated for them. The myth has been repeated over and over, sometimes by those who would prefer that you remain unaware (since then, it would be obvious that you could make the same product which you now pay another party to swage).

In the years just after the Second World War, right up until the mid-1970's, there was in fact some truth to this. Bullet swaging equipment was, at one time, only built for the benchrest shooter at high relative cost. World records were set by bullets swaged in these dies. A few firms tried to offer low cost versions but the result was typically poor, and nearly all of them went out of business eventually.

Partly because of the people who tried to cut corners and make cheap swaging tools, swaging got an undeserved bad reputation among shooters who had only tried the cheaper tools. (The same is true today: a handful of low-end producers do in fact make cheaper versions of Corbin tools, even copying the nomenclature and catalog numbering system. But it has always been easier to copy terminology than quality.) But over the past 50 years, Corbin's swaging equipment has become the world's leading standard for serious bullet makers, defense suppliers, and custom bullet firms.



How Does Swaging Work?


Several books have been written about bullet swaging without exhausting all the possibile uses or bullet designs. So rather than try to list every possible kind of bullet you can make, let's just take two examples to illustrate the basic tools:

Semi-Wadcutter Style



A SWC or Semi-Wadcutter style is not a specific shape, like a target wadcutter nose or a Keith SWC nose. It refers, in swaging, to any bullet that has a step or shoulder between the start of the nose and the straight part of the bullet (the "shank", or main body).

This kind of bullet can be formed in a die with a straight hole, rather than a bullet-shaped cavity like a point form die. The nose is formed in a cavity machined in the end of a punch. But before going further, let's define a die and a punch!

A "die" is the cylinder which holds the bullet material, in a cavity or hole of the desired diameter. A die is equipped with two punches, one at either end. In a swaging press, the die screws into the press ram. For Corbin swage presses, the dies are either -S type (for the smaller S-press) or -H type (for the larger CSP-2 Mega Mite or the powerful Hydro-Press). One end of the die is threaded to fit into the top of the ram. The die moves up and down with the ram to swage the bullet. In a reloading press, the die fits in the press head in a die holder with a captive internal punch.

A "punch" is a solid rod fitted to the die cavity, which seals pressure and forms one end of the bullet or at least ejects it (in a point form die). Punches are of two kinds: internal or external.

Internal punches stay in the die during operation, sliding up and down to eject the bullet. In Corbin swage presses the internal punch fits inside the ram. One end of the punch (the "head") rests upon a "ledge" or shelf created between two diameters of axial holes through the ram. This is what positions the ram in the die when the bullet is being formed.

External punches for Corbin swage presses fit into a punch holder (FPH-1-S or FPH-1-H depending on size of press). The punch holder fits the threads in the press head (the top). Turning the punch holder to move it up or down adjusts how far into the die the external punch will go at the top of the stroke. This is how adjustment is made for weight and length, amount of tip closure, and so forth. For a reloading press, the external punch fits into the T-slot in the ram, which normally accepts a shell holder.

The Lead Semi-Wadcutter (Cat.No. LSWC-1-S or LSWC-1-H) is most simple kind of straight hole swage die for making a finished bullet in one stroke. A straight-hole die has punches which are a close, sliding fit to the bore or cavity. They seal pressure and keep the lead or other material from squirting past the punch, or "bleeding" as it is called. A SWC nose shape of any sort can be machined into the end of one of these punches. Shape can be round, or conical, or truncated conical, flat, or with a slight bump to make a "button nose" wadcutter. The important factor is that any cavity machined into the nose punch MUST have a reasonably thick edge, at least 0.015 inches, to withstand the pressure of swaging and then sliding along the die bore. Pressures of 20,000 psi and more are common. Thinner edges on the punch would let it crumble or be pulled off like foil.

Because the edge must be there, on a SWC type nose punch, the resulting bullet cannot simply blend in one smooth curve from full diameter into a nose shape. It has to stop at the shoulder created by the punch end, and then the lead nose is formed in the punch cavity. But one stroke of the press results in a finished bullet. The LSWC-1 die has bleed holes around the circumference, so that once you set up a given insertion depth of the external punch, a specific volume of lead is left inside the die and the rest has to spurt out through the bleed holes. That lets you adjust the weight just by moving the top punch up and down in its punch holder.

A jacketed bullet could be made in the LSWC-1 die except that the jacket would cover the bleed holes. So a two die set is used instead, consisting of a smaller bore size bleed die which is called a "core swage" die, or CSW-1 and a larger bore (actual caliber size) straight hole die without bleed holes, called a "core seater" or CS-1 die. The combination of these two dies can be ordered under a single catalog number JSWC-2, with -S or -H added to indicate the press type.

If you do use a jacket on the bullet, the jacket length must be short enough so it does not go past the shoulder. Otherwise the jacket end and the punch edge would mash together and crush the jacket. The jacket edge has no way to "jump over" the punch edge. That is what defines, and limits, the SWC type die. You can use more than one nose punch in succession, including a big hollow pointing punch and then a round nose or Keith nose punch pushed slightly less far into the die. The combinations of different punches and how far you adjust the second one to partially reform the shape provides a great deal of experimental possibility. It's part of the fun of swaging to see what you can create.



Smooth Ogive Types



In order to get the edge of the jacket to smoothly flow around into an ogive shape without a step in it, we have to add a different design of swage die. This is the Point Form Die cat.no. PF-1-S or PF-1-H for Corbin presses, or PF-1-R for a reloading press. The point forming die is described in detail on another page (select the name to go there). But basically, it is a die having a cavity shaped like the bullet. The internal punch is just an ejector. For most jacketed bullets, the internal punch is made of a punch head fitted with a wire ejector pin in the range of .062 to .134 inches, depending on caliber and ejection resistance or force it needs to withstand. Some point form dies are equipped with precisely fitted ejector pins to do special tasks, such as making bullets with metal tip inserts or with precisely formed hollow lead tips and hollow point cavities. Regardless of the details, the PF-1 point form die has a smooth bullet shaped cavity in the exact shape of the bullet.

You can see that changing the internal punch would not change the ogive shape in this case. The diameter and the shape are set by the point form die, although the length and weight is adjustable, and different base or external punches can be used to make flat, cup, dish, hollow and rebated boattail bases (in conjunction with the core seating die).

The basic steps to make ANY bullet with a smooth ogive is to swage an exact weight of lead core in the CSW-1- core swage die, put this core into a jacket and seat it in a CS-1 core seat die (or in a RBT-2- rebated boattail base forming die set, which is discussed on another page), and finish the the ogive shape by pushing this jacketed cylinder (seated core and jacket) into the PF-1- point forming die.

So the steps to swage most bullets (flat base, open tip style) are:

  1. Cut or cast a lead core of about the right weight but a few grains heavier than desired. (Weight the jacket and subtract from final bullet weight).

  2. Swage the cores to the precise weight and size required in the CSW-1-S or -H type core swage die.

  3. Seat the core in the jacket using a CS-1-S or -H type core seating die (or in the two RBT-2-S or -H rebated boattail seater dies for RBT bullets).

  4. Form the ogive in the PF-1-S or -H point forming die.

The details about hollow points, open tips, lead tips, metal tips, and so forth can be found on other pages, but this is how swaging is done. Substituting the RBT-2-S or -H dies for the one CS-1-S core seater lets you make RBT (Rebated Boattail) bullets. Nicer lead tips are formed if you make the lead core longer than the jacket and then re-shape the tip in a LT-1-S or -H Lead Tip Finishing dies.

Individual dies are grouped into sets which make a certain bullet style, such as flat or rebated boattail bases, open or lead tips. The caliber can be anything within a certain range. The -S dies are made from .102 to .458 caliber, and the -H dies make anything up to about 1 inch diameter. Die sets are therefore discussed in terms of the bullet features, rather than the caliber.

When looking for a 9mm pistol bullet swage set, for instance, look for a flat base jacketed bullet set. Don't search for 9mm. The FJFB-3-S die set can be ordered in any caliber. For 9mm you would want to specify a 3/4-E nose, or maybe a TC nose, select appropriate jackets and lead wire (J-38-500 jackets, for example, with .312 lead wire), and a core cutter and lube. The same specs, except for jacket and wire size, could apply for 45, 40, 32, you name it. No point in listing every caliber known to man instead of just the bullet style with a blank to fill in for caliber.


The Source Behind the Scenes

For decades, Corbin Manufacturing has been quietly supplying high-quality equipment for the world's top custom bullet makers. Prices compare favorably to casting, especially when you consider that a single set of swage dies can make an almost unlimited variety of bullet weights and styles, and when you are finished pulling the handle of the press, you are DONE! No further sizing, lubricating, inspecting, rejects... only perfectly swaged bullets of precision diameter and weight, every time!

Carefully hand-built dies and individually machined swage presses made in the Corbin die-works represent the highest standard for professional or hobby bullet swaging. Since the beginning, handloaders and experimenters, businesses and defense agencies have lined up to get their names on the delivery list for Corbin dies. Demand has been so great that delivery took two to three years! (Today, from our new die-works, only about 10 percent of "standard" tools take longer than 90 days to build, and most custom tools are shipped within six months or less, depending on the current number and complexity of pending jobs.)

Corbin has become the world's leading source for bullet swaging partly because: (1) Corbin developed the semi-custom production method for swaging equipment, making it possible to offer every caliber from .142 to 1-inch projectiles both in custom designs and off the shelf, without having to design every swage set from scratch, and thus greatly reduced the cost of high quality tooling, and (2) Corbin offers a virtual one-stop shop for everything associated with bullet swaging, including more information (including eight books) and design software than had ever been assembled previously (or since) from any other source.



Corbin makes a wide range of presses and dies, starting with die sets you can use with an existing cartridge reloading press, right on up to floor-standing hydraulic swage presses that can form the most exotic hard lead or jacketed bullets, ranging from .14 caliber, 20-grain varmint wreckers right on up to .700 caliber, 1200-grain elephant stoppers and 1-inch cannon projectiles! Airgun pellets, fragmenting pistol bullets, or shotgun slugs -- virtually every bullet design you can imagine, is being made on Corbin equipment right now!



Corbin is the Professional's Choice

Corbin has spent years developing and producing the finest quality swaged bullet manufacturing tools for the custom bullet maker. From A Square to Trophy Bonded, there are literally hundreds of custom bullet makers who use Corbin equipment. Their results -- and the results of those who shoot and hunt with their bullets -- speak for themselves. Nearly all custom bullet firms in business today either use Corbin equipment or got their start with it! Armament laboratories and defense contractors around the world use Corbin presses and dies for their prototype development work and short runs of special projectiles. Corbin sets the standard for professional bullet making equipment of the highest precision and quality.

Thousands more bullet makers and competition shooters who enjoy making bullets for just themselves or a small circle of friends. They know that using Corbin swaging equipment means success -- success in terms of tighter groups, better stopping power, and saving (and making) money! At Corbin our motto is "We Manufacture Success." Whether your interest is in loading the most match-accurate bullets that can be made or in becoming a top-quality custom ammo maker, Corbin can help you achieve success.

Everything You Need

Not only do we offer presses, dies, and a full line of accessories, we also have the most complete information available, including eight books about bullet swaging and computer software to design bullets and run a custom bullet business. Start with the Corbin Handbook of Swaging, or the more comprehensive Bullet Swaging Library (seven books about bullet making) for a solid understanding of the field and the tools available. We furnish supplies such as jackets, jacket-making metals, lead wire, lubricants, bullet polishing kits, and bonding chemicals, and we can help you develop a custom bullet business from start-up concept through marketing.

How do you swage bullets?