Military Vehicles Spotlight: M50 “Ontos” Gun Motor Carriage

This particular vehicle M50 Ontos was used in the battle of Hue City in South Vietnam. The Marine Corps Mechanized Museum restored and houses it. Jerry Cook led the restoration project. Jerry Cook

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

HISTORICAL NOTES

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.

The Ontos had six M40 106 mm recoilless rifles that could be fired in rapid succession against individual targets. Jerry Cook

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.

June 1959 color slide of an Ontos is labeled, "The Thing." John Adams-Graf collection

Preston Sewell was an Ontos crewman from 1962-66 with the USMC 1st Anti-Tank Bn and 3rd Anti-Tank Bn. Communications

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.