G-288 M50 Gun Motor Carriage
- Weight: 19,050 lbs.
- Engine: GMC 302 6-cylinder
- Displacement: 301.6 cu. in.
- Horsepower: 127 @ 3,350 rpm
- Maximum speed: 30 mph
- Maximum range: 150 miles
- Armament: 6 x 106mm Recoilless Rifle and 4 x .50-caliber spotting
Officially known as the “Rifle, Multiple 106 mm, Self-propelled, M50,” the Ontos was a tracked, lightly armored anti-tank vehicle developed as a fast tank killer for airborne forces. It mounted six M40 106 mm recoilless rifles that could be fired in rapid succession against individual targets.
As an anti-tank vehicle the Ontos had several problems, including a small ammunition load, a very high profile for such a small vehicle, and the need for the crew to exit the vehicle in order to reload the guns, exposing them to enemy fire. After the Army lost interest in the project, the US Marines ordered 297 of the vehicles—the first was accepted in 1956.
During the Vietnam War, the relatively lightweight vehicle could go where other, heavier tanks would be bogged down and immobilized. The Marines used the vehicles mostly in direct fire support of infantry. In May 1969, the Marines deactivated the Ontos.