 The firing pin was fixed in the base cap of the tube, and the bomb was fired automatically when it dropped down the barrel.Though classed as a light mortar, the M2 had considerable range compared to the 50 mm and 60 mm mortars of most other nations, and its fixed-firing pin design allowed a high rate of fire by trained crews.During the late 1920s, the US Army began examining mortars to act as a light infantry support weapon.