Cartridge: 45 ACP
Rate of fire: 600 rounds/minute
Origin: Germany
The Heckler & Koch UMP (Universale Maschinenpistole, German for “Universal Submachine Gun”) was developed in the 1990s and features a predominantly polymer construction and direct blowback operation. These changes make the UMP series much less expensive to manufacture than the roller-delayed locking mechanism of the MP5. The fundamental differences between the 9mm, 40 S&W and 45 ACP versions are the bolt, barrel and magazine.
HeliBacon’s UMP 45 features a side-folding stock, straight polymer magazines, last round bolt hold open with a bolt release button, and a 0,1,2,F trigger group configuration. The subsonic nature of 45 ACP makes the suppressor quite effective as well.
The direct blowback operation, and associated heavier bolt, result in more felt recoil than the MP5 chambered in 9mm. However, compared to the Thompson, another 45 ACP chambered submachine gun, the ergonomics are superior, the functionality is greater, the overall weight is substantially reduced, and it fires from a closed bolt.
“Apples to apples, shoot a Thompson and a UMP 45 one after the other. Both subguns, both 45 ACP. Ergonomics have come a long way in a century.” - HeliBacon