Shooting the Thompson M1A1 submachine gun Magazine Military history Surplus arms 1 Comment 2015. June 5. Thompson M1A1 .45 ACp géppisztoly 30-as tárral Accuracy and penetration tests with some high frame per sec filmings! My impression about the thompson M1A1 submachine gun. Although I could only try this semiauto conversion I am sure that the gun handles well in burst mode as well.