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M50 Ontos

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This is an old revision of this page, as edited by 137.53.85.122 (talk) at 23:28, 8 November 2007 (Changes secondary armory to a single m1919 .30 cal because the spotting scopes were not m2 machine guns as previously indicated in the fact box.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Rifle, Multiple 106 mm, Self-propelled, M50 “Ontos”
Ontos M50A1, the 50-cal spotting rifles can be seen on the upper guns
TypeTank destroyer
Place of originUnited States
Service history
In service1956–69
Used byUnited States
WarsVietnam war
Production history
DesignerAllis-Chalmers
Designed1952
ManufacturerAllis-Chalmers
Produced1955–57
No. built297
VariantsM50A1
Specifications
Caliber106 mm
Main
armament
6 × M40 recoilless rifles
Secondary
armament
1 × .30-caliber machine gun
EngineGM 6-cyl 302ci.

The Ontos, officially the Rifle, Multiple 106 mm, Self-propelled, M50, was 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. The US Marines were the only force to use the Ontos operationally, and although their crews consistently reported excellent results against infantry during the Vietnam War, the Ontos was always considered an "ugly duckling" and was removed from service in 1969.

The Ontos (Greek for "the thing") project was created to be an air transportable tank-destroyer capable of being lifted by the cargo aircraft of the 1950s. This limited it to a weight between 10 and 20 tonnes, the only other limitation to the design being that it had to use the six-cylinder engine then widely used in the Army's GMC trucks. Allis-Chalmers was awarded the contract on August 12, 1955, for 297 vehicles.

Allis-Chalmers' first vehicle, completed in 1952, was based on the running gear of the M56 Scorpion light anti-tank vehicle. The vehicle, officially Rifle, Multiple 105 mm, Self-propelled, T165, mounted a cast steel turret with two arms holding three rifles each. This early model could traverse the turret only about 15 degrees. A second prototype used a new suspension system including new tracks, and a newer turret with about 40 degrees traverse. Only eighteen rounds for the main guns could be carried inside the vehicle due to limited space. Four of the rifles also had 50-caliber spotting rifles attached, firing a round that flew like the 106 mm round and gave off a puff of smoke on impact with the target. This meant that the 106 mm recoiless rifles were lined up with the target, and then they would be fired. A single 30-cal M1919A4 machine gun was also carried for anti-infantry use.

The prototype and testing stage was completed by 1955, at which point the Army cancelled its order. As an anti-tank vehicle the Ontos had several problems, including a lack of ammunition, a very high profile for such a small vehicle, and the need for the crew to exit the vehicle in order to re-load the guns, making them obvious targets for snipers. Although the Army cancelled their order, the Marines Corps were desperate for any anti-tank vehicles they could get, and ordered 297. Production ran from 1955 through 1957. The first vehicle accepted by the Marine Corps was on 31 October 1956.

Several variants were also studied. The Utility Vehicle, Tracked, Infantry, T55 was a light APC, but only two versions of the prototype were built. This proved utterly impractical due to the limited room inside, carrying only five infantry and forcing the driver to lie prone. A "stretched" version known as the Utility Vehicle, Tracked, Infantry, T56 was also built, and while it held a complete eight-man team, their equipment had to be carried on the outside. Neither was considered very useful.

In 1960 there was a brief study made to replace the Ontos's 106 mm rifles with a new 105 mm design that included a re-loading system similar to that on a revolver. This project was not accepted. However another upgrade was, replacing the GMC engine with a newer Chrysler 361ci, V8 engine. Of the 297 vehicles accepted by the Marines, only 176 were converted between 1963 to 1965. This newest version of the Ontos was named Rifle, Multiple 106 mm, Self-propelled, M50A1.

The Ontos was used widely in Vietnam as a fire support vehicle, and was particularly liked by its crews. They noted that the appearance of an Ontos was usually enough to make the enemy break and run. Nevertheless the Ontos units were deactivated in May 1969, and some the vehicles handed over to an Army Light Infantry Brigade. They used them until they ran out of spare parts, and then removed the turrets and used them as fixed fortifications. Both these and the rest of the vehicles returned from Vietnam in 1970, and were cut up for scrap, with some of the chassis being sold off as construction vehicles.

Survivors

  • The Patton Museum of Cavalry & Armor in Fort Knox, Kentucky has an M50A1 Ontos on outside display. The vehicle has just undergone a full operational restoration.
  • The Rock Island Arsenal Museum in Rock Island, Illinois has an M50A1 Ontos on display in an outside area called the Memorial Park.
  • A prototype T165 is in an outside display area at Camp Atterbury along with 30 to 40 other military vehicles. The outside museum is located along Hospital Road near Highway 65 about 30 south of Indianapolis, Indiana.
  • Two Ontos are on display at the American Heritage Park, a private outdoor museum in El Monte, California. These Ontos do not have their 106mm rifles. Mr. Craig Michelson of American Heritage Park said he judges his vehicles to be 80% complete.
  • Mr. Fred Ropkey, owner of the Ropkey Armor Museum in Indianapolis, Indiana owns the first prototype T165, a later model Ontos and a parts machine.
  • The U.S. Marine Corps Museum in Quantico, Virginia has completed the restoration of an M50A1 Ontos.
  • The U.S. Marine Corps Museum of the Carolinas in Jacksonville, North Carolina has an operational M50A1 Ontos which is not on public display.
  • There is an M50A1 Ontos on outside display at the Navy Facility at China Lake, California. Permission to enter the facility must be requested at least 24 hours prior to a visit.
  • The Military Vehicle Technology Foundation in Portola Valley, California has a T165E1 prototype with the original GM 302ci engine which is currently undergoing a complete operational restoration, and a second prototype T165E2 Ontos.
  • A complete M50A1 Ontos in operational condition is privately owned in Hockley, Texas. The vehicle is a restored former Forestry Service vehicle. The owner uses it for public demonstrations and displays.
  • A M50A1 Ontos is privately owned in Staten Island, New York. The vehicle is a former Forestry Service Ontos and is currently being restored to military configuration. It is not available to the public.
  • A M50A1 Ontos is privately owned in Vine Grove, Kentucky. The vehicle is a former Forestry Service Ontos and is planned to eventually be restored to military configuration. It is not on public display.
  • Two retired Marines claim to have seven former Forestry Service Ontos hulks that they are attempting to combine and restore into several operational Ontos in military configuration.
  • The U.S. Military reports that about 74 hulks remain in a desert "dumping ground" though the location is restricted and off limits to the public.
  • An Ontos can be seen in action on a CBS DVD set about Vietnam. Its on the disc about TET and HUE.
  • An Ontos can be seen coming down a street in Hue on the "Battle for Hue" episode of the Military Channel's show "Combat Zone".
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