The M2A1 is a 90mm AAA piece was a grpund based weapon system for longer range interception of aircaft and be able to enage enemy armor on the ground of needed. Based of the M2 90mm which was based of the M1 90mm and later became the M3 90mm found on the tanks like the M26 Pershing the M2A1 had good velocity and range amd when grouped in a battery the M2A1 would prove to be effective againt targets at quite a distance away and when linked to a central FCS and radar system improved its lethality even more. The M2A1 came with an assisting rammer to help load rounds at a faster and constant pace.