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| 106mm Self-propelled Rifle M50A1 Ontos |
The impressive-looking M50 Ontos (in the Greek meaning "The Thing") was built to a United States Marine Corps tank destroyer specification. With five prototypes built, and each fitted with differing calibers of recoilless rifles, the T156 design was born. No fewer than 24 of the type were ordered for further trials, each armed with six of the powerful 106mm recoilless rifle type. From the T156 trials emerged the T156E2 which gave rise to the production M50 - each slightly modified from the predecessor. A switch to a Chrysler-based petrol engine produced 294 models of the M50A1 series, which in itself included evermore modifications to the system.
At it's core, the M56 was fitted with a common turret mounting six of the M40A1C recoilless rifles. Additionally, the top four 106mm mounts were fitted with 4 x 12.7mm (.50 caliber) heavy machine guns to act as spotters when aligning the main guns. The use of the spotting machine guns was directly after optical sighting was completed. The spotter machine guns were then fired to accurize contact. Shortly thereafter, the recoilless rifles could be fired with some degree of accuracy.
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| Photo of an Ontos at the National Museum of the Marine Corps taken in August 2007. |
All weapon systems on the M50 were limited in ammunition-carrying capacities. The 106mm recoilless rifles were limited to just 18 projectiles spread across the six guns. The 12.7mm spotting machine guns were limited to just 80 rounds of ammunition. Not to be left high and dry against advancing enemy infantrymen, an additional 7.62mm machine gun was mounted to the top of the turret for self-defense.
Besides the limited ammunition situation, crew quarters once inside the machine were cramped at best. Additionally the weapon systems could only be reloaded from outside the vehicle, exposing the crew to dangerous enemy fire. The system saw action in South Vietnam and in the hands of the United States Marines. No longer in service with the Marine Corps, no replacement vehicle was selected to succeed the M50 Ontos on the modern battlefield, the assumption being that other weapon systems are more likely up to the task of tank destroyer than a similar self-propelled recoilless rifle design like the Ontos.
