Military Power

The Ontos was officially the Rifle, Multiple 106 mm, Self-propelled, M50, a light anti-tank vehicle developed in the US in the 1950s. It mounted six M40 106 mm recoilless rifles as its main armament, which could be fired in rapid succession against single targets to guarantee a kill.

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In 1951, work began on a new vehicle for the US Army to replace the range of World War II vintage Tank Destroyers. The US Army soon lost interest in the project, but the USMC saw a need for a light weapon that could be landed by air or sea.

To reduce weight recoiless guns were proposed as the armament, but because of the backblast from these weapons they had to be mounted outside of the vehicle which meant that the crew would be exposed when reloading, thus multiple guns were proposed so as to allow several shots to be fired before the guns needed to be reloaded.

The M50 106mm Self-Propelled Multiple-Rifle (ONTOS) appeared in 1963 armed with six 106mm Recoiless-Rifles on a traverse turret (two of the guns could be dismounted and used on tripods for ground use if required).

The ONTOS was used operationally by the Marine Corps in Vietnam and in the Dominican Republic (usually as ground support weapons rather than in the Anti-Tank Role) but suffered from the drawback that the backblast could often give away the vehicle's position and draw return fire onto the infantry they were supporting.

The ONTOS vehicles were withdrawn from service and scrapped in 1970.

A rather similar AFV was the Japanese Type 60 Self Propelled Gun (in service c.1960-1980). The Type 60, which was built by the Komatsu Manufacturing Company, was armed with a pair of U.S. 106mm recoiless rifles mounted in a light weight tracked chassis with a low superstructure. It was powered by a rear mounted 120 bhp Komarsu T120, 6 cylinder inline air cooled, diesel engine which could propel the AFV upto 30 mph. The twin 106mm R.R.s would be raised hydraulically for firing by the vehicle's commander (who was situated with his sights in a cupola on the left side of the hull), but once fired it was necessary for the loader to have to leave the vehicle in order to rearm the guns. Thus the Type 60 needed to withdraw, after every two shots, into cover to allow this operation to be accomplished.