THE 10mm AUTO CARTRIDGE

The 10mm was designed in the early 1980's and introduced in 1983. Incorporating features that Col. Cooper (ret.), one of the founders of IPSC, thought would be desirable in a handgun cartridge. Dornaus & Dixion introduced the 10mm with their pistol, the BREN TEN. Unfortunately, Dornaus & Dixion had trouble supplying their pistol to the public. At the time, NORMA, manufacturer of ammunition in Sweden, was manufacturing 10mm ammunition and would have stopped producing this powerful cartridge if a firearm was not chambered for it. Fortunately, COLT Manufacturing Co. re-engineered the 1911 to handle the 10mm.

Originally, NORMA loaded their 200gr.(grain) bullet at 1200fps (feet per second) and the 170gr. bullet at 1400fps. The original loads are very powerful, and I have chronographed the 170gr. bullet with velocities between 1335 to 1360fps from my S&W 610 5" barrel. I have heard and it seems confirmed that the early NORMA 10mm cartridges were not loaded too carefully. None the less, the NORMA loads are more powerful than those loaded by the major ammunition manufacturers today. Currently, there are numerous bullet weights available for the 10mm. The weights range from 135gr. to 210gr. The 10mm is a strong cartridge and is able to hold up to punishing pressures. The case was designed to withstand 53 000cup (maximum proof test round), a very impressive feat when other automatic handgun cartridges fall below 40 000cup.  Original NORMA loads had cup pressures of +40 000.  Current 10mm loads are anemic to original hot loads, and probably average only 38000cup.  Most commercial loads have a mean pressure starting at 37 000cup and some of the more powerful loads go up to 45 000cup. Next to the .45ACP (22 000cup), and 9mm (35 700+cup) maximum pressures, the 10mm Auto is powerful indeed. Comparing the 10mm to magnum cartridges, the maximum pressures range from 46 000cup for the .357MAG down to 43 700 for the .41MAG and .44MAG. Due to the high velocities that the 10mm generates, it is a very flat shooting cartridge, which helps with longer shots. The 10mm achieves its peak pressure very quickly, and therefore needs either a strong recoil spring or strong lockup to contain the gases until the pressures become safe. The various semi automatic designs used to shoot the 10mm have strong recoil springs in order to slow the slide velocity.

All the major ammunition companies have or still have the 10mm in their line up, but not as extensive a range or selection one would expect. Unfortunately, the obscurity of the 10mm has hurt it from being developed by the ammunition companies. This is due to the popularity of the .40S&W. Personally, I do not have any love for the "Short & Weak", but it is very popular with police and civilians primarily because it is able to be fired from a 9mm design platform. The main reason why many like the .40S&W is that it has an increased magazine capacity, usually 10 to 15 rounds. Another reason is the .40S&W is popular is that it has a reduced recoil impulse compared to the 10mm, but came close to the "stopping power" of the venerable .45ACP. The main reason why the 10mm AUTO didn't gain popularity with shooters was that, in it's original loadings, it is a very powerful semi-automatic cartridge. For new shooters, who may be recoil sensitive, most would shy away from a gun that is a real "kicker". In addition, another negative factor is that the handguns that chamber the 10mm are inherently on the large side in order to contain the cartridge's power. And there in lies the demise of the 10mm AUTO. With few new novice shooters taking on the 10mm and the various guns chambered for it, the 10mm AUTO has languished with little attention or much development. This is unfortunate because the 10mm AUTO is one of the better handgun catridges out there for general purpose shooting. The 10mm can be downloaded for plinking or targetshooting, or loaded hot for game hunting. Hopefully, shooters out there will appreciate the 10mm and BUY ONE!!! hehe...doing my part to support the 10mm!!!


A family photo of the 10mm/.40 caliber family and few cousins:

.38-40WCF, .401POWERMAG, .41MAG, .41AE, 10mm, .40S&W



This page will not explore the .40S&W even though it is a caliber cousin to the 10mm. A comparison of the two cartridges can be seen HERE . The .40S&W is explored in depth at several other web sites that do an excellent job describing the capabilities of the .40 "Short & Weak".


As an interesting side note, for a brief period of time a 10mm Magnum cartridge was available and one factory gun was produced to shoot this very powerful cartridge. There is a significant difference in case length between the 10mm and 10mmMAG. IAI produced a 10mm Magnum handgun called the IAI Mark IV 10mm Magnum (pic). The barrel is long and has a "bulb" where the bushing is located. The locking lug is a kidney shaped design that is fully enclosed. The 10mmMAG had ballistics on par (or maybe even a little better) with the .41 Magnum. The advantage that the 10mm Magnum had over the .41Magnum was that it was able to fire from a semi-auto design. A very limited number of the IAI/AMT guns were manufactured (less than 100?) and all coming with a couple of boxes of custom ammunition using STARLINE BRASS loaded by (I think) SIERRA. Over the years, I have heard various "one of's" being produced to fire the 10mm Magnum, but no manufactures have chambered this cartridge. About the only ammunition specifications I have is this small blurb, "From a custom 10mmMAG cylinder, the 610 shot 1 1/2" @25 yards The IAI was 3 1/2". The ammo was American Ammo 220 gr, 1335 fps, 792 ft-lbs. Powerful!"


Another cartridge based on 10mm brass is the 9x25mm. This cartridge uses a 10mm case necked down to fit a 9mm bullet. The shoulder angle for this round is very steep and short. The 9x25mm was developed for IPSC shooting competitions and makes Major no problem. It is a light recoiling, very flat shooting cartridge that allows for little adjustment when taking shots at distance. If you are using a compensator, there is negligable muzzle rise. Standing next to someone shooting a 9x25mm handgun gives a new meaning to feeling the recoil...one can actually feel the power of the 9x25mm hitting the body. It is also a VERY LOUD cartridge (definately double plug with this one)!!! The velocities that are generated from this round are impressive, over 1500 fps with the lighter 9mm bullet weights. The only guns I have seen chambered for this round are custom guns and barrels. Mostly, they are 1911 pattern handguns, but there are barrels available for the Glock 20. While the .357SIG is similar, the 9x25mm is far more powerful. Take a look at the 9x25mm HERE (pic) and a Para Ordnance 9x25mm (pic) tricked out by Guntrixs (link).


I have news on a pseudo 10mm cartridge that "may" be in development for the Austrailian SAS. It is a 10mm cartridge necked down to a .224 50gr bullet. Velocity is supposeto be around 2200fps and it can shoot from appropriately modified Glock 20 and HK MP5. Recoil is supposedly the equivalent of hot 9mm...not much muzzle climb. Can you all imagine modifing your G20 to this round? hehehe...now if I could only get the resizing dies...forget 9x25mm!The company that developed this round is called Civil Defense Supply (link) and they have some very interesting stuff on their page.
I was able to get my hands on a .224BOZ and it does look like an interesting cartridge. The case is a necked down 10mm case from STARLINE and utilizes what seems to be a 55gr. FMJ .223 bullet. I tried fitting the round in my Glock 20 magazine, and it does indeed fit nicely in. The .224BOZ did initially seem longer than the 10mm, but I did not take into account the invisible ogive of 10mm. Too bad this round will not be available for commercial sales as I think it would be a great varmitter cartridge from a handgun or a carbine.Here are some pictures from the CDS site (with permission) that are worth a look just for interests sake. If you want to see more, click onto the CDS link above.
1. .224BOZ (pic)
2. Modified Glock 20 Link doesn't work (pic)
3. Modified Glock 20 Link doesn't work (pic)
3. Modified HK MP5 10mm Link doesn't work (pic)
4. Modified 1911 test gun (pic)


CDS has discontinued the use of the modified G20 due to concerns that the Glock 20 design is not appropriate for use with the .224BOZ. CDS has concerns in 5 areas that they did not disclose, but they are now looking for a new platform for the .224BOZ. If you read the Guns & Ammo article, CDS may be going with a customized wide frame 1911. I guess we'll have to see what CDS uses.

There is a detailed write up of the .224BOZ in the November 1998 issue of "Guns and Ammo". More info there than I can put on the page, but I'll add more when I can.


The Grand Daddy of all significant 10mm/.40 caliber cartridges is the .38-40. Originally a cowboy gun cartridge used in SAA revolvers and lever action rifles. For it's day, the .38-40 was the modern ballistic equivalent of the 10mm. It is a flat shooter with high velocity and was not as popular as other cartridges of the day. With cowboy shooting events becoming more and more popular, the .38-40 is coming out in small numbers at these events. Hopefully the .38-40 will become popular enough for major firearms companies to chamber it (and maybe a convertible cylinder in 10mm or 10mmMAG!!!). A stainless RUGER Varquero in .38-40/10mm (like the Ruger Blackhawk from Buckeye's) would be ideal for SAA events and all around pleasent shooting.