Special Weapons’ USC M-3

By Chris A. Choat

A couple of years ago Heckler & Koch introduced their USC (Universal Self-Loading Carbine) as sort of a vague civilianized cousin to their UMP (Universal Machine Pistol) submachine gun. To comply with the letter of the law the new carbine had a proprietary 10-round magazine, non-folding thumbhole style stock and was molded in a very non-threatening gray color. Even in it’s straight-from-the-factory disguise, the little carbine is typical H&K, robust, well built and totally reliable.

The UMP is one of the latest in a long line of very successful H&K submachine guns, starting with the H&K MP5. The UMP submachine gun utilizes a fiber-reinforced plastic receiver very similar to the technology used in the new H&K G36 series rifle. H&K calls the receiver material “tough, lightweight, glass-fiber reinforced polymer”. It is a recoil-operated submachine gun that uses a large, non-delayed, long-recoil, blowback bolt. It fires from the closed-bolt position. The UMP was introduced in caliber .45 ACP, but now is also available in .40 S&W as well as 9mm Parabellum, although the 9mm guns are not available in the United States. Cyclic rate of the .45 ACP model is between 600 and 700 rpm depending on the ammunition used. It is fed by polymer magazines that come in 25- and 10-round versions for the .45 ACP model. It incorporates a skeletonized stock that folds to the right side of the weapon and the gun can be fired with the stock folded. It is just shy of 28 inches long with the stock extended, weighs right at 5 pounds, empty. The UMP’s barrel is 7.87 inches long with a polygonal bore with a right hand twist of one turn in 16 inches. The barrel features a machined quick-coupler for a sound suppressor. One other key feature is a total of eight molded-in, steel, threaded hard points for the attachment of various accessory mounting rails. Two of these hard points are on the top of the gun just forward of the rear sight, the other six are at the 3, 6 and 9 o’clock positions around the forearm. These rails in turn allow the mounting of accessories such as optics, tactical lights, vertical foregrips, hand-stops, etc. The gun also uses interchangeable trigger housing/fire control groups that allow for semiautomatic and full-auto fire as well as two and three-round burst fire. These fire control groups use the now well-known “pictograph” or “bullet markings”.

Now back to the subject at hand: the USC. The H&K USC shares a lot of the same features as the UMP. The USC is gray instead of black like the UMP. The USC’s 10-round magazine was insufficient, especially so for SAR readers. Then there was the thumbhole style stock. It not only looked very out of place but it just didn’t fit my hand very well. Now an Arizona company is about to change all that.

Special Weapons, Inc., of Mesa, Arizona has done some amazing things with the H&K USC. First they addressed the 10-round magazine limitation. They are now producing a complete trigger housing/magazine-well conversion that allows the USC to use standard unmodified, made in America, Grease Gun 30-round magazines. That’s right, the new housing simply replaces the stock polymer magazine housing and allows the owner to use the Grease Gun 30-round magazines without any permanent modifications to either the gun or the magazines. The new magazine housing is CNC-machined from 6061 T6 aluminum alloy and then it is black anodized. It features the “bullet markings” just like the original H&K version. The markings are deeply engraved into the housing and look great. The magazine catch/release on this new housing is on the right-hand side instead of on the bottom in front of the trigger guard as on the factory housing. Now instead of releasing the magazine with the thumb of the support hand you can release it with your trigger finger.

Special Weapons has also addressed the issue of the color of the stock. They can dye the gun to a nice dark black color! Their dying process actually penetrates the stock to a depth of about 1/8-inch. This way if you happen to ding or scratch the stock you still have the black color showing instead of gray. The original markings on the stock are retained and there is almost no darkening of the red H&K emblem. The same goes for the “bullet markings” on the original magazine housing if you decide to retain it. Their dye color is an exact match of the color of the H&K UMP submachine gun. Because the gun is dyed all surfaces inside and out on the gun get colored.

The magazine housing is a drop in part. It comes without internal parts. All the user has to do is disassemble their existing housing and reassemble the parts into the new housing. The new housing is then installed onto the gun, a 30-round Grease Gun magazine inserted and you’re ready to go. If you don’t have a USC, Special Weapons is offering a limited run of complete H&K USC’s dyed black with their new magazine housing already installed. They call this gun the USC M-3.

Special Weapons recently sent me one of their complete USC M3’s for test and evaluation. The gun arrived with a one 30-round Grease Gun magazine, a magazine loading tool and a barrel shroud. This shroud is also offered by Special Weapons. It looks like the old Sionics M16 suppressor. It slides over the barrel and is held in place by three Allen head set screws. With the shroud in place, the gun looks like a UMP with a small diameter suppressor.

I installed a red dot sight and shot the USC M-3 almost every day for the three weeks that I had it. Recoil and noise are very mild. But, the best thing about the Special Weapons USC M-3 is that it was TOTALLY reliable. In the three weeks that I tested the gun I kept a tally of the rounds put through it. When it was all said and done we fired 1,450 rounds without malfunction. The first 800 rounds were fired using the magazine that came with the gun. Thinking that the magazine had been modified or specially prepared I used two of my own Grease Gun magazines. They also performed flawlessly. Over ten different types of .45 ACP ammunition was used in this test and evaluation - from low velocity cast bullet reloads to ultra high velocity jacketed factory ammunition. Bullet weights and types also varied widely - everything from 185-grain wadcutters to 230-grain +P+ hollow points.

Accuracy from the gun was just about what you would expect from an H&K. Groups measured right at 2 inches at 50 yards with the red dot sight. I think that they would be even less with a scope with a crosshair reticle. The best accuracy was recorded with Black Hills ammo. We tried some Aguila .45 ACP High Power ammunition. This loading is produced for law enforcement and military use. It features a 117-grain hollow point bullet that chronographed out of the USC M-3 at almost 1,800 feet per second. The USC M-3 fed 100 rounds of this load without a glitch.

You are probably wondering how Special Weapons can legally turn a 10-round gun like the USC into a 30-round gun. It all has to do with the number of US made parts in the gun. Every gun that was affected by the assault ban has to have a certain number of US made parts in it to legally be able to use a high-capacity magazine. This number varies with each gun. The H&K USC M-3 has to have a total of three US made parts. In this case the Grease Gun US-made magazine body is one, the magazine follower makes two and the magazine floorplate brings the total to three. The trigger housing counts for one more.

The nice thing about using Grease Gun magazines is that they are still plentiful and inexpensive. I still see them in gun publications for as low as $10.00 each. While the Grease Gun magazine can be loaded without a loading tool, it’s a lot easier if you have one; especially those last 10 rounds.

For those of you out there that already have a USC you too can enjoy the “30-round advantage”. The stripped magazine housings are available separately. While Special Weapons has designed and engineered the magazine conversions, it and completed guns are sold through two of Special Weapons “sister” companies. Tactical Weapons Training Academy handles the sale and distribution of complete guns and Top Notch Accessories, Inc., handles the sale of parts and accessories. One other accessory that is worth mentioning is Special Weapons new aluminum top optic rail. The top optic rail that comes with the USC is made from polymer. While it is light and most optics lock up to it fairly tight, it has a certain amount of flex to it. With the new aluminum rail from Special Weapons the flex is gone and optics mount very solid. This makes for even better accuracy from an already accurate gun.

You can buy a complete gun that’s already dyed black with the magazine housing conversion installed and ready to shoot, or if you already own a USC just add a magazine housing conversion and send the gun to Special Weapons for a dye job. By the way, as far as the thumbhole stock goes, rumor has it that Special Weapons may be working on a pistol grip stock that will fit the USC. If they are, you can bet that it will make this great little gun even better. I enthusiastically recommend the Special Weapons USC M3.

Special Weapons LLC
P.O. Box 22139
Mesa, AZ 85277-2139
Phone: 1-480-325-7885

Top Notch Accessories, Inc.
284 E. Chilton Drive, Unit C-12
Chandler, AZ 85225
Phone: 1-480-633-1222

Tactical Weapons Training Academy
4613 E. Ivy Street, Suite 102
Mesa, AZ 85205
Phone: 1-480-830-5652

This article first appeared in Small Arms Review V6N7 (April 2003)
and was posted online on November 29, 2013


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