M13 Half-track

M13 Multiple Gun Motor Carriage
A restored M13
Type	Self-propelled anti aircraft gun
Place of origin	United States
Service history
In service	1943–44
Used by	United States
Wars	World War II
Production history
Designer	White Motor Company
Designed	1940–42
Manufacturer	White Motor Company
Produced	1942–43
No. built	1,103
Specifications
Length	21 ft 4 in (6.50 m)
Width	7 ft 1 in (2.16 m)
Height	7 ft 8 in (2.34 m)
Crew	5 (commander, driver, gunner, and two ammunition loaders)
Main armament	2 × 0.5 in (13 mm) M2 Browning machine guns in a Maxson M33 turret mount
Engine	White 160AX, 386 in3 (6,330 cc), 6-cylinder, gasoline engine, compression ratio 6.3:1, 128 hp (95 kW)
Power/weight	15.8 hp/ton
Suspension	Half-track, vertical volute spring for track, bogies for wheels.
Fuel capacity	60 US gal (230 l; 50 imp gal)
Operational range	175 mi (282 km)
Speed	45 mph (72 km/h)

The M13 Multiple Gun Motor Carriage (MGMC), otherwise known as the M13 Half-track, was a self-propelled anti-aircraft gun used by the U.S. Army during World War II that was armed with two .50 caliber M2HB heavy-barrel Browning machine guns. Developed in response to a requirement for a mobile anti-aircraft (AA) vehicle, the vehicle was produced by the White Motor Company between July 1942 and May 1943. The only time it was ever used in combat was when the Americans landed at Anzio in January 1944. It was replaced by the more heavily 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. Of these, the T1E4 was selected and given the official name of the M13 MGMC, before being placed into production. Half of the M13s produced were converted into M16s on the production lines.

The M13 Half-track was 21 feet 4 inches (6.50 m) long, 7 feet 1 inch (2.16 m) wide, and 7 feet 8 inches (2.34 m) high with a wheelbase of 135.5 inches (3.44 m). It had bogie suspension for the wheels and vertical volute springs for the tracks. It had a 60 US gallon (230 l) fuel capacity and a range of 175 miles (282 km). The vehicle was powered by a six-cylinder White 160AX, 128 horsepower (95 kW), 386 cubic inches (6,330 cc) gasoline engine, with a compression ratio of 6.3:1. It had a power-to-weight ratio of 15.8 horsepower per ton and weighed nine tons. The armor across most of the vehicle was 0.25 inches (6.4 mm) thick with a 0.5 inches (13 mm) thick windscreen visor. The vehicle was armed with two 0.5 inch M2 Browning heavy machine guns placed on an M33 Maxson mount. The two machine guns were fired remotely and powered by a small electrical motor near the back of the turret. The guns were aimed with a Mark 9 reflector sight. Each vehicle had a crew of five (commander, driver, gunner, and two ammunition loaders).

In October 1940, development began to produce a vehicle in response to a long-standing requirement for an anti-aircraft vehicle to protect the U.S. Army's mechanized troop convoys from aerial attack. The first vehicle produced in the development of a half track with an anti-aircraft armament was the T1, which had two M2 machine guns on a Bendix machine gun mount—as used on jeeps—on a 4×4 truck. The T1E1 had a power-operated Bendix mount, and the T1E2 a Maxson mount. The T1E3 had an electro-dynamic Glenn L. Martin Company aircraft-type turret. Evaluation of these test vehicles led to the T1E2 design being preferred. The T1E2 became the M16 Half-track by replacing the M33 with the M45 mount and the M2 Half-track chassis with the M3 Half-track chassis.