The Probert Encyclopaedia of Warfare

THOMPSON

The Thompson sub-machine-gun was an American weapon developed from the 1920s. It took a .45 inch round from a 50-round drum or 20-round box. It had a 267 mm long barrel, a cyclic rate of 700 rounds-per-minute and a muzzle velocity of 281 meters-per-second. The original Thompson M1921 was slightly modified to the M1928 which was adopted for service with the American Marines and later evolved into the simplified model M1 which was developed in 1942 with out a locking breech, but using a simple blowback operation.
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