The M1A1 was favored by soldiers and civilians alike for its compactness, large .45 ACP bullet, and high volume of automatic fire

Compared to modern 9mm submachine guns, it is heavy, difficult to aim and has excessive recoil. By the standards of the day, however, the M1A1 was one of the most effective and reliable submachine guns available.

Fires .45 ACP rounds from a 30-round detachable box magazine.