M50 Ontos

Rifle, Multiple 106 mm, Self-propelled, M50 "Ontos"
Ontos M50A1, the 50-cal spotting rifles can be seen on the upper guns
Type	Tank destroyer
Place of origin	United States
Service history
In service	1956–69
Used by	United States
Wars	Vietnam War Dominican Civil War 1958 Lebanon Crisis
Production history
Designer	Allis-Chalmers
Designed	1952
Manufacturer	Allis-Chalmers
Produced	1955–57
No. built	297
Variants	M50A1
Specifications
Mass	8,600 kg (19,000 lb)
Length	3.83 m (12 ft 7 in)
Width	2.59 m (8 ft 6 in)
Height	2.13 m (7 ft 0 in)
Crew	3 (driver, gunner and loader)
Sights	x6 .50 Single-Shot Spotting Rifles
Main armament	6 × M40A1C recoilless rifles
Secondary armament	1 × .30 (7.62 mm) M1919 Browning machine gun
Engine	GM 6-cylinder inline 302 cu in (4.95 L) gasoline engine 145 hp (108 kW)
Operational range	185 km (115 mi)
Maximum speed	48 km/h (30 mph)

Ontos, officially the Rifle, Multiple 106 mm, Self-propelled, M50, was an American light armored tracked anti-tank vehicle developed in the 1950s.

It mounted six 106 mm manually loaded M40 recoilless rifles as its main armament, which could be fired in rapid succession against single targets to increase the probability of a kill. Although the actual caliber of the main guns was 105 mm, it was designated 106 mm to prevent confusion with the ammunition for the 105 mm M27 recoilless rifle, which the M40 replaced.

It was produced in limited numbers for the U.S. Marines after the U.S. Army cancelled the project. The Marines consistently reported excellent results when they used the Ontos for direct fire support against infantry in numerous battles and operations during the Vietnam War. The American stock of Ontos was largely expended towards the end of the conflict and the Ontos was removed from service in 1969.