M3 3-inch Anti-Aircraft Artillery
As early as 1915, developments in aircraft led the U.S. Army to recognize the need for a high-angle firing antiaircraft gun. Resolving to build one from existing stocks using 3-inch shells, they chose the M1903 seacoast defense gun and redesignated it the M1917 fixed mount gun. Soon after America's entry into World War I, however, the requirement for a mobile mount with less recoll compelled the selection of the less powerful M1898 seacoast gun for conversion to the M1918 mobile antiaircraft gun. Development of both guns and mounts continued throughout the interwar years, leading by 1930 to the standardization of the mobile 3-inch gun as the M3 on the M2 wheeled mount.
Early in World War II, the M3 3-inch (76.2 mm) Anti-Aircraft Gun was the standard medium AAA until the 90mm Anti-Aircraft Gun was available in quantity. The M3 3-in. gun used the same M2 (or M2A1 or M2A2) carriage as the Bofors 40mm antiaircraft gun, with an axle and wheels at each end and four long stabilizing outriggers that folded for travel. The gun platform, when its folded sections were deployed, supported the crew while allowing for 360° traverse of the gun.
The M3 3-inch AAA could hit an aerial target at a maximum horizontal range of 14,780 yards and could reach just below a 10,000-yard ceiling, firing its 12.87-pound HE rounds at up to 25 rounds per minute. The same gun was initially used in shipboard and ground installations and used the same ammunition as the M5 3-in. anti-tank gun. As with other AA artillery, the gun was used against ground targets when the tactical situation called for it. Both the Army and the USMC were equipped with the M3 3-inch Anti-Aircraft Artillery until it was replaced by the 90mm AAA in mid-1942.
M3 3-inch Anti-Aircraft Artillery emplacement on Corregidor before its fall to the Japanese in 1942.
No. 2 Gun Crew, Btry D, 208th CA AA with their M3 3-inch Anti-Aircraft Gun at New Fighter Strip, Dobodura near Buna, New Guinea, 17 May 1943.