The M13 Multiple Gun Motor Carriage (M13 MGMC) was a World War II self-propelled anti-aircraft gun produced by the White Motor Company when the United States needed a mobile anti-aircraft (AA) vehicle. Production commenced in July 1942 and ended in May 1943. The only time it was ever used was when the Americans landed at Anzio in January 1944. It was replaced by the better armed M16 Multiple Gun Motor Carriage in April 1944.
The M13 evolved from a series of several unsuccessful prototypes that were trialed from 1940 to 1942 until the T1E4 was selected, given an official name (the M13 MGMC), and it finally started production. Half of the M13 production were converted into M16s on the production lines.
The M13 Half-track was 21 ft 4 in (6.50 m) long, 7 ft 3 in (2.16 m) wide, 7 ft 8 in (2.34 m) high with a wheelbase of 135.5 in (3.44 m). It had bogie suspension for the wheels and vertical volute springs for the tracks. It had a 60 US gallons (230 l) fuel capacity and a range of 175 mi (282 km). The vehicle was powered by a White 160AX, 128 hp (95 kW), 386 in3 (6,330 kW), six cylinder, gasoline engine, with a compression ratio of 6.3:1. It had a power to weight ratio of 15.8 hp per tonne and weighed nine tons. The armor across most of the vehicle was 0.25 inch (6 mm) thick with a 0.5 in (12 mm) thick windscreen visor. The vehicle was armed with two M2 Browning heavy machine guns mounted on an M33 Maxson Mount. The two machine guns were fired electrically and powered by a small electrical engine near the back of the turret. The guns were aimed with a Mark 9 reflector sight.