The Thompson M1A1 is a variant to the American Thompson Submachine Gun. This weapon was issued to American soldiers during October of 1942; which was well into World War 2 and was used for most of the war. This variant was capable of using 20-30 round magazines and 50-100 round drums; chambered in the .45 ACP ammunition. It was also a select fire weapon and was best fired in full automatic fire. Unlike the other variants; this version used a bolt on the side; rather than it traditionally made to be a telescopic bolt like it's predecessor. It was used in the Pacific and Europe.