Production of the vehicle started in March 1941 and continued until October 1943. Like its direct predecessor, the M2A4, the M3 was initially armed with a 37 mm M5 gun and five .30-06 Browning M1919A4 machine guns: coaxial with the gun, on top of the turret in an M20 anti-aircraft mount, in a ball mount in right bow, and in the right and left hull sponsons.
