Bullet jackets are frequently drawn at the factories from gilding metal or commercial bronze (5% to 10% zinc, balance copper) in thicknesses that will stand up well to the higher velocities to which the caliber will be subjected. This sometimes means that in order to sell safely to the general public, the average load has to be considered, and then the bullet built to handle it with additional jacket strength.

The rise in popularity of concealed carry weapons of light weight, and light weight titanium, scandium, and various kinds of polymer frame guns coupled with shorter barrels means that many traditionally well-built general purpose bullets do not expand well, or at all, when fired from these guns. Making the more brittle zinc-alloy jackets thinner usually results in making them more likely to shatter or split in unacceptable ways when they do try to expand. But pure copper jackets can be made very thin, with proper grade and heat treatment of the metal, and still tend to mushroom in the classic, desirable way at lower velocities.

There is a growing market for bullets that can be hand loaded to (1) expand reliably at lower velocities from the shorter barrel CCW type guns, (2) be loaded down to help retain control of light guns with heavier calibers such as .45 ACP, .44 Special, and .40 Auto, and (3) provide handloaders and bullet makers with a premium quality thin jacket, as an alternative to the premium heavy wall jackets used for the heavy load, hunting handguns.

The demand is large enough to keep several individuals busy supplying it, but not so large as to attract much attention from the mass producers, who must justify producing millions of jackets in long runs to keep the cost within their volume/pricing curve. By definition, the low cost producers are high volume manufacturers, and must look to the average buyer's needs rather than to the specialty handloader. Even though the CCW market is quite large, the number of shooters handloading their ammunition with custom bullets, either of their own making or from a custom bullet maker, is still below the threshold that would interest most of the major bullet makers. This is exactly the market gap which Corbin's bullet swaging and jacket making equipment is designed to handle economically.

With the CSP-2H Hydro Junior, you can manufacture jackets without physical exertion. Someone with a bad back, or other health issues that would keep them from operating a hand press for any length of time, can push the buttons and make excellent bullet jackets (or the bullets, for that matter, with additional swage dies). Anyone can benefit from the tireless precision of a hydraulic power press.

The market for thin jackets extends beyond pistol calibers. Using the same base material, a 1 inch wide by .030-thick pure copper strip (available on 50-lb coils or in 5-lb bundles from Corbin), the JMK-1-H package offered first makes a .600 diameter short, thick cup and then draws it to a .500 diameter half jacket. These preliminary steps produce cups that have limited commercial use, other than for sale to other bullet makers who may wish to redraw them to make their own calibers, but do not wish to invest in the blanking and cupping tools. (This is a small but steady market, also.)

But the .500 diameter half jacket is necessary to produce all the other jackets. Virtually any smaller caliber can be drawn from it by adding appropriate JRD-2-H commercial draw dies and ET-2-H jacket trim dies. Trimming is sometimes required between draws, because the jackets become so long that they may exceed the usable punch length. In the first draws, such as .45, .44, and .40, the jacket length is still within the range of acceptable punch length, and the wall thickness is maintained at .015 inches with a .030 thick base. Jackets can be taken down to .352 or so to make 9mm and 357 pistol calibers, but at this point they become long enough to also make rifle caliber bullets.

At .400, the jackets are long enough to begin making 300-350 grain bullets for light, high velocity jacketed loads for .40-65WCF and similar rifle calibers. The thin jackets prevent leading and are easy on the older barrels of vintage Winchesters, Ballards, and Marlins. As the jacket is drawn on down toward 9mm, the jackets require trimming with the ET-2-H trim die (simply set the die for desired length, insert the jacket, and stroke the press). Jackets are trimmed precisely with the die method without filing, cutting, or deburring. Appropriate trim dies are included with the package.

At a draw of about .306 diameter, the jackets are appropriate for making all the .30 pistol and rifle calibers including bullets up to 200 grains in certain shapes (round nose lead tips can be made much heavier than long spitzer open tips, as well as much lighter...the more pointed the nose, the more limited the weight range on both ends of the scale). The thin jackets are not designed or intended for big game hunting. They are about .010-inches thick, which is excellent for target and varmint shooting for two reasons.

First, the thin jacket has less over-all effect on bullet balance than a thick one, because any variation in wall thickness is a smaller percentage of total weight. These will be excellent jackets in any case, but there is no such thing as perfect concentricity. Every drawn jacket will have some degree of run-out, even if it is unmeasurable with ordinary instruments. The thinner the jacket wall, the less absolute variation there will be. After all, you can't have .001 inch runout if the jacket is only .001 inch thick, or it would cease to exist! But the main effect is that if the space that a .025-inch thick jacket would have taken up is now filled with the core material for .015 inches on both sides (for a .010 wall jacket), there are .020 inches more solid core in the cross section.

This means that the density of the jacket (cross sectional density, which is diameter divided by weight) will increase for the same length and shape of bullet, by using the thin jacket. If the sectional density is increased, the BC of the bullet goes up by the same amount (since BC is just the form factor or Ingall's number times sectional density).

Today, there is a great deal of emphasis placed on higher BC bullets. Whether or not it is reasonable or serves a valid purpose, the BC number has become a "figure of merit" that is used in advertising. It has become important, perhaps out of proportion to other factors, for many shooters to seek the highest BC bullets they can find.

Using the thin jackets lets you, or your clients, make higher BC bullets than they could using exactly the same equipment and core material, but a thicker jacket. This is the second benefit, besides less "wobble" from potential imbalances caused by jacket wall variation. Your jackets will have these two features that are factual, supportable, and ultimately good marketing points.

The fact that you can make seven popular calibers (actually, more calibers...since the diameter of the jacket is just the starting point, and is expanded in the swage die, you can actually make many calibers from each jacket: the .38 makes all the calibers from .380acp, 9mm, .357 Mag, .38 Special, .38 Super, 9.3mm Mararov, etc. and can be trimmed longer to make .358 rifle, .35 Whelen, .360 Wby, .366 (9.3), and other similar diameters) is a good business basis. By adding other draw and trim dies, you can make virtually any caliber smaller than .45. The length cannot be made long enough in .45 to build a .458 rifle jacket, but by the time you have drawn the jacket to 9mm, you have enough length to build virtually any rifle jacket (7mm, 270, 6.7mm, 6.5mm, 257, 8mm, and so forth).