Design
The UMP seems to have been squarely designed for the U.S. law enforcement market. Being fully auto restricted it to police and military buyers, and .45 ACP is a distinctly American round. There were other chamberings, including 9mm and .40 Smith & Wesson, but they were all smaller than the .45. The UMP was designed around the .45 cartridge.
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The USC was released at around the same time, with many modifications to meet the strict import restrictions of the time. Besides being semi-automatic only, a fixed thumbhole stock and a 16-inch barrel were added. To satisfy the magazine restrictions, the USC didn’t take the double-stack UMP magazines. Instead, it could only use proprietary single-stack magazines.
Unfortunately, neither the UMP nor the USC gained much acceptance. The MP5 was a tough act to follow. Recoil was greater on the UMP than on the MP5 because of the direct blowback design. Being lighter weight but firing a more powerful round didn’t help, either. The UMP was just not as smooth or controllable as the MP5, and that was its death rattle.
Features
Starting from the front, this rifle has an aftermarket faux suppressor shroud over its 16-inch barrel. It also has aftermarket Picatinny rails on the top, sides and bottom, and a foregrip. The exterior is a molded polymer shell. There is a trunnion on the inside where the barrel is fitted.
Like the MP5 design, the charging handle is non-reciprocating and can be locked open by flipping it into the rear notch with the “HK slap.” There is also an AR-15 “ping-pong” style bolt lock and release. This is because the bolt locks open when the last round is fired.
The magazine release is paddle-style and easy to access with either hand. The single-stack magazine well is narrow, but mags insert smoothly and lock up tightly. The front iron sight is shrouded. The rear sight is protected by wings and the user can choose between a peep or notch with a simple flip. The safety selector is classic MP5-style with a short and positive throw.
Bolt & Trigger
The bolt is big and heavy, because it is the weight of the bolt that controls the action. There is also an out-of-battery safety integrated into the bolt, making the design very reliable and safe. In theory, it should be even more reliable than the MP5 since the action uses fewer moving parts and should be more resistant to debris and fouling.
The trigger feels mil-spec with a heavy take-up. The break is about 6.5 pounds with a solid feel. The reset is about medium– long but loud and tactile. The grip is blocky and integrated into the stock. There is a 14.5-inch length of pull, and the overall weight from the factory is about 6 pounds.
Takedown is simple: just remove two screws on either side of the receiver. On the UMP these are push pins, but the USC has screws. After that, everything comes apart easily just as on an MP5.
Pros & Cons
I like this gun. It’s light, accurate, and reliable. The trigger is a little heavy, but I didn’t notice it when shooting. I was able to get great groups.
I think criticisms of this gun are overrated. The most common complaint is about the recoil. The way people talk, you would think it was uncontrollable. It is more energetic than an MP5, but it is on par with any lightweight carbine shooting .45 ACP. If you have any good shooting mechanics, you will have no problems controlling it.
Now, I assume the criticisms come from the police and military world. When shooting full auto, I can see that the UMP would me more difficult to control than an MP5, but that’s not really a concern for us civilians.
On the other hand, I didn’t like everything that had to be done to make this gun U.S. legal, starting with the thumbhole stock. The length of pull is too long for me and probably for most average or smaller shooters. The integrated grip is huge and boxy, making manipulating the safety difficult.
The addition of the 16-inch barrel and the accessories from the original owner make this gun very front-heavy. Finally, the single-stack magazines are limiting, and the gun makes so much more sense with double-stack mags as originally designed.
Conclusion
I like the USC, but I really want the UMP. Since you can’t get the UMP, you have to start with the USC as a project. The conversion is easy – well, everything except being fully automatic. You can’t do that.
Otherwise, the parts the snap together. All you need to do is change the barrel, stock, grip, and lower receiver. It is an expensive project, though. HKs are expensive and so are the replacement parts, but you don’t have to do it all at once. The base USC is still fun to shoot and looks super cool. If you upgrade one part every year or two, before you know it, you will have a civilian UMP.
