The UMP is a blowback-operated select-fire submachine gun firing from a closed bolt. It features a polymer stock that is able to be folded for compactness, a paddle-style magazine release, and a handguard that is able to accept accessories, such as vertical foregrips. The barrel is approximately 8 inches long, and there may be rails on top of the receiver to mount optics.
The UMP45 has a cyclic rate of 600 RPM; the UMP40 and UMP9, 650 RPM. This was done to help counteract the effect of recoil when firing.
The selector switch features three modes of fire: SAFE, SEMI, and AUTO.
The USC (Universal Self-loading Carbine) is the Title 1 version of the UMP. It features a thumbhole grip instead of the UMP’s pistol grip and a longer barrel (16 inches).