Thompson M1928/M1A1

Adopted by the US Army in 1938 the M1A1 was modified from the original Thompson design to speed up production by simplification. The changes included the removal of the h-piece, the substitution of a heavier bolt to compensate. Externally the main differences were the absence of the compensator on the muzzle, the substitution of a straight forehand for the forward pistol grip, the removal of the complex backsight and it's replacement by a simple flip sight. The use of the drum box was dropped and the normal 20 round box mag could be used plus the newly introduced 30 round mag box. The Final change was the incorporation of a fixed firing pin on the face of the bolt. The weapon was heavy to carry, but did have considerable stopping power. The weapon is 32" long, a 10.5" barrel with a muzzle velocity of 920 f/s.