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Bullet Jackets

General Jacket Information

Jackets are the "skin" of a bullet, starting as empty cylinders which are then filled with compressed core material, expanded to exact diameter, and shaped into the bullet desired.

Jackets are usually made 0.003 to 0.006 inches SMALLER than the actual bullet diameter, to allow for expansion as the core is seated, which results in a snug grip between the "stretched" jacket and the inserted core (usually made of lead, but can be any compressible material or powdered metal). Cores generally need to be able to flow under pressure in order to expand the jacket. Jackets are not "put on" the core; instead the jacket is blown up like a balloon by the tons of force applied to the malleable core during core seating.

Much of the tooling design for jacketed bullets begins with the jacket length, diameter and wall thickness.

Therefore, it is important to decide what jacket you wish to use first, so you can determine the size of the core swage die, the core seating punch, and the length of the bullet. The caliber and length determine if the bullet can be made in a small hand press, or if it will require larger dies and either a Mega Mite press or the Hydro-Press.

For comprehensive instructions about jacket making and bullet swaging, you may wish to purchase the Corbin Handbook of Bullet Swaging (HB-9E on CD-ROM) and/or the multi-media package BP-7, both available directly from the Corbin web store www.SwageDies.com.

You can purchase drawn bullet jackets from Corbin in some stock sizes and lengths, but it isn't practical for anyone to carry the thousands of possible calibers, lengths, materials, tapers, and wall thicknesses that would be used in so many individual circumstances. However, you can make bullet jackets yourself, at home, to more precisely fill your exact needs, if a stock jacket won't do the job.

You can also use Corbin JRD-1 Jacket Reducing Dies of various diameters to draw down existing factory made jackets to smaller calibers (which also become longer). If you want a shorter jacket in the same diameter as the original, you can use the Corbin ET-2 Adjustable Jacket Trim Die.

Corbin .45 jackets With the ET-2 you CAN trim virtually ANY caliber to ANY reasonable length in nearly ANY thickness. Remember that jackets typically TAPER inside, so the base is usually VERY thick and the portion near the mouth is normally VERY thin in comparison. Tubing jackets are the exception, as they often are straight walled. But of course, you cut the tubing to desired length before you make the jacket, so trim dies are not usually required for tubing jackets.

The ET-2 is an ADJUSTABLE die that expands the mouth of the jacket you want to trim, to whatever distance you want to cut off (from the open end), then it snips off the expanded portion in one stroke. It can be set to any length within reason for trimming a longer jacket. Each die is for one caliber (diameter) of jacket. These are available in types -S, and -H for current Corbin presses. The type -H trim die is a type -S with adapter kit to fit the ram and the larger punch holder of the -H presses. If you already have one caliber of -H trim die, you can simply purchase -S trim dies and use the same adapter with them. A manual-ejection (knock-out) type of die called the ET-1-R is available for use in a reloading press.

Bullet jackets can be made at home in several ways, including:
    Drawn Bullet Jackets
  • Drawing and end-closing copper tubing with a Corbin CTJM-1 Copper Tubing Jacket Maker die set.
  • Lathe turning from solid bar stock. This isn't usually as consistent as drawing.
  • Drawing down a larger caliber of ready-made jacket to a longer, smaller diameter.
  • Reforming fired .22 LR cases into good quality but thin walled .224 or .243 jackets, using the Corbin RFJM-22 or RFJM-6M dies.
  • Reforming fired shotgun primers into fair quality thick walled .25 ACP jackets with the Corbin SPJM-25 Shotgun Primer Jacket Maker kit.
  • Drawing strip copper or jacket alloys into commercial quality tapered wall jackets using
    • JMK-1-S Jacket Maker Kit, hand-operated, in the Corbin CSP-1 Series II press. This is limited to about half-inch maximum length, and to .45 caliber, using 1-inch wide by .030-thick strip. Other calibers can be produced by redrawing and trimming, with JRD-2-S commercial jacket draw dies and ET-2-S trim dies. The .45 can be taken to .40, the .40 to .35, and the .35 to .30 (or any size between).
    • JMK-1-H Jacket Maker Kit, hydraulic powered, in the Corbin CHP-1 Hydro-press. There is virtually no limit to length and diameter or thickness of jacket with this large, powerful set, within the stroke limits of the press. It can be used in the CSP-2 Mega Mite press for most standard calibers in reasonable wall thicknesses, with up to 1.5-inch long jackets.
    • JMK-2-H Jacket Maker Kit, hydraulic powered, in a modified Corbin CHP-1 Hydro-press (using the special press head adapter that comes with the kit). This adds automatic strip feeding when coupled with the Corbin CSU-1 Strip Uncoiler machine. The strip is fed, lubricated, punched into a disk and drawn into a cup without manual handling at a rate of about 50 cups per minute. The cups must then be redrawn from one to four times and trimmed, depending on the specific jacket dimensions. It is most convenient to have a second press, either hand or powered, to complete the jacket drawing operations. Ideally one would have one press set up for each step, for maximum production.

RimFire Jacket Maker Kits

Rimfire Jacket Maker This is probably the ONE product most shooters have heard about, because the process of using fired .22 cases as jackets for centerfire .224 and .243 rifle bullets launched so many of the giants of reloading, such as R.C.B.S., Speer, Hornaday, and others.

Corbin has offered the RFJM-22R, RFJM-22M, RFJM-6MR, and RFJM-6MM die sets for decades. Shooters use them to turn fired, empty .22 Short, Long, or Long Rifle cases into excellent thin-jacketed, explosive .224 centerfire rifle jackets or 6mm (.243) centerfire rifle jackets. The RFJM- stands for Rim Fire Jacket Maker. The -22 or -6M designates whether the die set is for making 224 or 243 caliber bullet jackets (the only difference is the punch and extractor mechanism). The final R or S determines whether the punch is for a standard slotted ram reloading press, or for the 5/8-24 TPI threaded ram of a Corbin S-press.

The quality of bullet jacket you can make with free .22 cases is excellent. It has no more problem with bore fouling than a normal jacket, perhaps less. It has less friction in the barrel than a normal factory bullet, so it is actually easier on the bore than firing factory bullets. You cannot load these thin jacketed bullets as fast as a factory bullet, so this forces you to use less powder, and wears the bore even less! The bullets act like they impact at 4,000 fps even when you fire them at less than 3,200 fps (which you should, to keep them from coming apart due to high rotational force on the .010 to .015 thick jacket walls). Rimfire Case Bullets

Fired .22 cases make the very best varmint bullets, and probably the worst big game jackets (certainly not recommended or ethical from a hunters point of view to use such thin explosive bullets on big game). As target bullets, they can be extremely good, beating even some benchrest bullets. We do NOT recommend them for serious benchrest use, though, because when you pick up spent cases you run the chance of different lots, different firing pin dents, and thus differences in the final jacket temper or hardness that might cause the groups to become wider than they should. If you are looking for groups in the half-inch to one-inch range at 100 yards, fired .22 cases will do a great job. If you are looking at groups of .20 to .30 inches, they can do it if you sort every case by lot and make sure the original firing pin dents are the same, and use a lot of care in forming the bullet. But for record setting groups, use commercial or drawn jackets.

These are the ultimate plinker bullet because they are so very accurate, easy on the bore, and cheap! (as in FREE). The process is quite simple: gather up fired .22 cases, toss out the flattened ones and the ones that have firing pin dents torn all the way through, wash them in boiling water and detergent, spread them out to dry on a towel. Then use Corbin Swage Lube on your fingers as you pick up the cases, slip them over the punch, and push them into the die.

I like to push them in just far enough so the head is ironed out as the end of the stroke is reached, only about 3/16 inch or so into the die. That makes it easy. Use the full press leverage to unfold and iron the head back into a straight wall section (as it was originally, when the case was built).

Then I lower the ram, eject the jacket, and process another one. When I have done about 500 of them, I lower the ram slightly and push each one through all the way in a longer, but easier, stroke. Having unfolded the head, the rest of the draw is easy now. Doing it all at once is possible, but takes more effort and a perfect adjustment of the die so you get exactly the maximum leverage at a point where the jacket just disappears into the die. Doing it in two strokes is a lot more flexible and easier on your arm.

After about an hour, I have processed 500 of the little jackets. I put them on a little tray made out of fire bricks stacked side by side, and heat them with a propane torch using a fan-tail spreader nozzle until they just barely get visible red in a dark room. Let them cool, or scoop them into a pail of water if you are in a hurry (has no effect on the temper of the brass). Dry them, and use them as you would any other jacket (but use a .204-inch diameter core seating punch, since they are thinner than the commercial jacket which uses a smaller punch, normally about .198 to .201 inch).

You can make 45-50 grain bullets with .22 short cases, 50-60 grain with a .22 LR case, 55-65 grain with a .22 Stinger or other longer .22 case, and in the .243 caliber you can get a nice lead tip 65 grain bullet with a .22 LR case. You can also use the .22 Magnum but not in these dies: that case is thicker and requires a different, special die set which Corbin makes. The .22 Mag produces a 105 grain 6mm and can also be expanded to .257 caliber. There are good illustrations of .22 RF case bullets in the new Corbin Handbook No.8 and detailed discussion of the old myths and misconceptions regarding the use of such materials.

(One example: during the early years from 1930-1950 the priming mix in 22 cases was corrosive, which made the cases brittle. When used as a jacket in those days, the brittle cases flaked apart in the bore and caused fouling. Word got out the using fired .22 cases was bad for your bore. Well, sure it was, back then. But manufacturers don't use corrosive priming mix any more, and have not done so for decades. That was the whole problem, and it doesn't exist any more, but the myth still continues in some people's minds. Part of the reason is that shooters love to read old gun books, but many of the stories in them deal with problems that don't exist today. If you don't know the reason behind some of the statements, then you can easily become fooled into thinking the problems of the early days still exist.)

Drawing Jackets from Strip Drawing Bullet Jackets

Corbin offers three separate processes for drawing your own jackets from strip copper:

The JMK-1-S is a set of tooling that will make jackets up to .45 caliber from 1 X .030 strip copper, in lengths that are most easily produced when under 0.7 inches at the large caliber end and under 1.25 inch at the smaller caliber end (.25, .30). It is economical to purchase, somewhat slow to operate because of the many required steps, but capable of producing good quality drawn jackets with a specific width and thickness of material. It is subject to a stringent limit on the length of medium and large calibers. For material/caliber/thickness/length specifications, see 1 x .030 STRIP CHART.

The JMK-1-S works ONLY in the CSP-1 S-press and ONLY with material that is specified or supplied by Corbin. We cannot make this tooling for any other strip material, for aluminum or brass or something you found in the barn. It works well if we supply the right material and perhaps not at all if you try to use anything else. However, we stock the right material in 5-lb bundles and 50-lb spools, and it is excellent quality deep-drawing grade copper with high finish and edge preparation for correct feeding (eliminating hangups from burrs, curls, turned edges, etc.).

The JMK-1-S makes .452 caliber jackets, and you can then add JRD-2-S commercial grade jacket draw dies and ET-2-S trim dies for each smaller, longer draw. However, bear in mind that there is a stringent length limitation as the diameter goes up...there is only so much material you can draw with a hand press, and this thickness and diameter represents the practical limit. With a limit on the volume of metal to work with, something has to be a limit on size, and it is the product of diameter and length. As ones goes up, the other must come down.

The JMK-1-S can also be ordered for .224 jackets, using 5/8-wide x .030 strip. This makes a good range of lengths for .22 caliber bullets, which can also be redrawn to make .20 (5mm), .19, .17, and even .14 caliber jackets. The use of 5/8-inch wide strip is more efficient (better use of material, lower cost per jacket) in the .22 caliber and smaller sizes, compared to using 1-inch strip.
The JMK-1-H is a more sophistocated system that can produce nearly any length, caliber, and most thicknesses of jackets suitable for strip drawing. Materials from .030 to .125 inches in thickness have been drawn, and jackets as large as .700 Nitro or as long as a three-inch .512 have been made with this set. There are lower limits on length, thickness and caliber when the set is used with a hand press (CSP-2 Mega Mite), but even these are within the normal range for small arms bullet jackets.

The steps involved include:
  1. Make the disk (coining die) by punching it from the strip.
  2. Cup the disk in the cupping die
  3. Redraw the disk from 1 to 5 times depending on the jacket.
  4. Final draw and trim stage uses adjustable trimmer die.

To make such a set for you, we need to know the maximum length jacket you wish to make. Any shorter jackets are simply a matter of adjusting the final trim die, but you don't want to specify too wide a range if you plan on making very many jackets of the shorter lengths, because it wastes too much material. We have to design the set for the largest, longest, heaviest wall jacket you plan to make. Then this jacket is, in effect, used to make anything shorter, thinner, or smaller by "throwing away" surplus material in the original jacket design.

Thus, if you plan to make a few hundred short .30's and a few 7mm's by drawing and trimming the 30's, it would be fine to do it with a jacket maker designed for 1.2 inch long .308's. But if you wanted to sell thousands of .30 carbine bullets for .30 pistols in 80 grain weights, it would be a waste of material and poor planning to get a single .308 JMK-1-H set made for the 1.2-inch jackets, because the shorter jacket could be made starting with a smaller amount of material. Thus, instead of 1.25 inch wide .050 thick copper, you might use 1 inch wide .030 inch thick copper. This completely re-configures the entire die set, which is built around the raw material dimensions, and indicates that you would want two die sets, one for the short and one for the long jacket, provided you needed a fairly large quantity of the short jackets. Otherwise, you could waste half the material and, until the material cost approached that of another set of dies, it would still be economical to make both lengths on the set built for the longer one.

The JMK-1-H set works by hand-feeding the strips of copper into the blanking die, then placing the "coins" into the cupping die in a second operation. A production rate up to 50 pieces per hour is fairly typical, because of the number of steps (a minimum of four, average of six, sometimes as much as eight, depending on length, thickness, and caliber). The JMK-1-H can be used in the CSP-2 hand press if the material thickness is held to .030 or less. Otherwise, it is used in the CHP-1 Hydro-Press.

The JMK-2-H set combines the operation of blanking (coining) and cupping into a single semi-automatic step, fed by the CSU-1 Corbin Strip Uncoiler (a required accessory for any reasonable production). It is only for use in the Corbin Hydro-Press. It is not practical to try to convert this system to any other press. The built-in sensors, conveyor belt, shut-down mechanism, feeder, lubricators, strip cutter, and drive cam system are specific to the dimensions and controls of the CHP-1 press.

To operate this system, you first load the CSU-1 uncoiler with a 50 or 100 pound coil of the proper strip material for the die set. Generally this is one of the following width X thickness combinations in pure 99.95% deep drawing, edge finished copper, available from Corbin:
  • .625 x .030
  • .750 x .030
  • 1 X .030
  • 1.25 x .030
  • 1 X .050
  • 1.25 X .050
  • 1.4 X .093

The strip is fed from the CSU-1 through a set of sensors to the feeder at the back of the Hydro-Press (part of the JMK-2 package). The standard head assembly on the Hydro-Press is removed and the head assembly for the JMK-2 is installed, which takes about 30 minutes. Once set up, the head assembly is used for automated feeding, lubrication, blanking and cupping of the strip. The large, shallow cups produced are fed out the press into your box or container, and the scrap copper from the strip is fed out the front into your recycle box (collect and resell the scrap copper). Normally, if you need the capability of the JMK-2-H die set, you will want a second Hydro-Press which is used for re-drawing and bullet making. With two presses you do not have to remove the auto-feed head, and replace it with the standard head every time you need to do re-drawing or bullet swaging. In some cases, the CSP-2 Mega Mite can be used for the secondary operations and the bullet swaging, depending on the caliber and length of the bullet.
JMK-2-HJMK-2 lubrication and feed mechanism
The machine feeds in the strip, blanks and cups it, and shuts down when the coil runs out. It is virtually unattended operation (but someone needs to be nearby to feed it more material or take away scrap or boxes of cups). However, the cups are not finished jackets. They may require from one to six more draws before they are ready to use. The cost of further automation becomes so costly that it would pay to purchase a dozen Hydro-presses and put various people to work redrawing jackets instead of buying a single high speed transfer press system, unless you plan to make millions of jackets a year. In the range of from 10,000 to 300,000 or so jackets a year, the JMK-2-H system fits the market niche perfectly because it was designed for this market. Its production rate is a good match for the typical custom bullet cost and rate of return consistent with the capital outlay. Moving in the direction of higher production speed vastly increases the capital cost, often to the point where a project is no longer viable.

To finish the jackets, either redraw them on a second press (which can be the CSP-2, or CHP-1) or wait until a sufficient number of cups are produced, then take down the JMK-2-H press head and replace the standard Hydro-Press head, and use it with the redrawing and trim dies. Normally it is feasiable to do this with 50 lbs of material processed. The number of jackets this makes is too dependent upon the jacket caliber, length, and taper for a guess, but here is how you can estimate it based on your jacket:
  • Determine the approximate weight of your proposed jacket. (Corbin makes the DC-CUPS computer software to help you design jackets and tells you this among other things). A typical .308 1.2 inch jacket might weigh about 50 grains, and a typical thin wall .45 ACP short jacket might weigh 35 grains. A heavy wall .458 jacket might weigh 100 grains.
  • With a conversion efficiency of about 80%, figure the material use per jacket as x = wt/.8 where wt is the jacket weight and x is the total material used to make it.
  • Divide x into 350,000 grains. The answer is the number of jackets, within an educated guess, that you can expect to make with a single 50-lb coil of copper strip. It is usually several thousand.

Corbin Bullet Jackets Corbin Bullet Jackets

To see or download a current table of Corbin precision drawn bullet jackets, select the picture of jackets above.

If you've been looking for bullet jackets, you know that Corbin is one of the few reliable, long-term sources where prices are still reasonable and quality is top notch. We are constantly adding new jackets to our line. But we also make jacket trim dies, jacket re-draw dies, and complete jacket drawing systems for both strip and tubing...if you want a jacket, you can get it or the means to make it, from Corbin. Any caliber, any length, and any wall thickness can be produced using Corbin equipment. Since the 1970's, Corbin has been your one-stop shopping center for bullet jackets, as well as all other bullet swaging products.

Stock jackets include the most popular calibers and lengths. But you can buy a supply of a stock jacket and redraw it to make other calibers that are not available from stock. For instance, if you need .30 Carbine jackets, you can either buy a long Corbin .308 jacket and an ET-1 jacket trim die, or you can purchase Corbin 9mm/38 stock jackets in .50 or .670 inch length, and a JRD-1 jacket drawing die to pull the 9mm down to a longer 30 caliber.

Corbin stocks 9mm/38 (same jacket size, as the swage dies will expand the slightly undersized jackets to proper diameter) in four lengths, .40 caliber (which works for .41 also), .44 (.429-30) caliber, and .45 (.451-.458) caliber handgun and light rifle jackets.

Corbin VB Versatile Benchrest Jackets At last: A Benchrest Jacket good enough for Hunting!

Versatile Benchrest Jackets from Corbin Corbin's VB (Versatile Benchrest) jackets are made for world-class competition, but we saw no reason why the world's finest target jacket could not also be designed to offer superior game hunting and varmint shooting performance. We started with a non-fouling, smoothly expanding copper alloy material drawn precisely over mandrels to exacting wall thickness. But we added features for custom bullet makers: thin nose-section walls that would accept the same seating punch diameter over a wide range of weights, and provide excellent expansion even at lowest velocities, with a gentle taper back to a heavier base to allow controlled expansion at higher velocities, especially when used with Corbin Core Bond to make bonded core bullets.

Corbin VB jackets are available in .224 (5.56mm), .243 (6mm) and .308 (7.62mm) caliber. These are designed for the most popular weights (50 to 60 grains in .221-225 calibers, 80-120 grains in 238-244 calibers, and 160-240 grains in .300-.312 calibers). But unlike many so-called "target" jackets, these are properly heat treated so that they will draw easily to form smaller calibers, such as 7mm, .270, 6.5mm from the .30 jacket, or .20 (5mm), .172, .142, and .123 caliber from the .224 (yes, we make 12 caliber!).

To make shorter jackets in the same caliber, use the Corbin ET-1 trim die and rapidly pinch trim (the most accurate, burr-free method) to any shorter length. To change the .22 or .30 jackets into smaller calibers, use the Corbin BRD-1 bullet reducing die.

Corbin's VB jackets are sold in packages of 500 (for the 22) and 250 (for the 243 and 30). A special for Benchrest Shooters is the bulk carton packaging of the same press run and lot number, at a discount from the double-bagged 250 or 500 size:

Cat.No. Qty/Box Caliber/Length
J-22-BOX 4,500 224 cal x .705 VB
J-6M-BOX 2,500 243 cal x 1.023 VB
J-30-BOX 1,300 308 cal x 1.25 VB
Click for pricing

For those calibers not stocked, you can get the next larger diameter of stock jacket, and a JRD-1 jacket draw die, to produce the size you want. For example, for 7mm (.284), 6.5mm (.264) and .277 (.270) calibers, simply purchase .30 jackets and the appropriate JRD-1 die. You may also want an ET-2 jacket trim die for the desired caliber, since drawing a jacket also makes it longer. For .14 caliber, use .17 and a draw/trim set. For .20 (5mm), use .224. For long, heavy .224's, use a .243 and redraw it to produce a thicker wall, longer .22 jacket.

Please note that when you draw down an existing commercially drawn jacket, the ID will usually be smaller than the ID of a stock jacket of the same caliber. That is, if you make a long heavy .224 from a .257 jacket by redrawing it, the resulting jacket will require a smaller diameter lead core than the stock Corbin .224 benchrest jacket. While a .185-inch diameter lead wire works with a .190 core swage die to fit the .224 Corbin jacket ID, it won't fit into the drawn 243 or 257 jacket.

For drawn .243 or .257 jackets made into .224 caliber, you will want .170 diameter lead wire, and a core swage that is in the .175-180 diameter range. You can also make a .224 jacket from fired .22 LR cases, or from 1/4-inch thin-wall copper tubing (which, in spite of the fact that it is called thin wall, is really quite thick for a bullet jacket and makes excellent game hunting bullets for heavy .224-.228 caliber bullets). To determine the size of core swage die you need for a given jacket, take twice the wall thickness away from the caliber, and then subtract another .005 or so from this figure. Anything this size or smaller should fit.

Example: a tubing .308 jacket using .032-inch thick copper tube would have walls of .032 X 2 = .064 inches, so .308 -.064 = .244 ID. But tubing can thicken slightly as it is formed, so figure about .005 less (.244 -.005 = .239). A core swage die normally is made .251 diameter for drawn Corbin .30 jackets. But for tubing, you need .239 or smaller.

Also, your core mould or lead wire may be a different diameter. A .251 core swage for the stock .308 jacket takes a .247 lead wire (standard size). This won't fit into the core swage die for tubing .30 jackets (.235-.239 typical size). So, you would need the next smaller standard wire size, which happens to be .218. In a core mould, you could use .224-.230 diameter, or stay with the .218 size.

Send your order by e-mail:

Remember to include a postal mailing address in your e-mail message! Our fax number is 541-826-8669. Our voice phone is 541-826-5211, and is answered by real people from 9-AM to 5-PM, Monday through Thursday, and by a computer with hundreds of answers and voice information files any other time.You can always mail to us using this address:

CORBIN, PO Box 2659, White City, OR 97503 USA

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