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M16 5.56mm Rifle

M16/M16A1
XM16/XM16E1

The M16 and M16A1 rifles are lightweight, air cooled, gas operated, magazine fed, and shoulder fired. The rifles may be fired with selector lever in the automatic or semiautomatic position, allowing for fully automatic fire or individual shots. The M16 5.56mm rifle does not contain the forward assist assembly contained on the 5.56mm Rifle Ml6A1. Both models may be equipped with the low light level sight assembly.

Though the US Army had been actively investigating Small Caliber High Velocity (SCHV) rifles during the 1950s, it was the US Air Force that adopted the AR-15 type first, awarding a contract to Colt in 1961. The rifles were intended to replace the M2 carbines then in use by USAF Air Police. The weapon was effectively unmodified from its commercial form, not recieving a US military designation initially in any of the US military nomenclature systems.

Elements of the US Army and the Office of the Secretary of Defense subsequently lobbied for adoption of the weapon by that service. The Army type standardized a variant with a manual bolt closure device (referred to generally as a "forward assist"), which allowed the weapon's action to be closed manually, as the XM16E1 in 1963. The designation XM16 was effectively retroactively applied to existing AR-15 rifles then in service lacking this feature. That the term AR-15 was commonly known already for those weapons, the XM16 nomenclature existed largely on paper. By 1964, the US Army had adopted the XM16E1 as the standard arm for Special Forces, Airborne, and Airmobile troops. Other US Army elements would continue to use the M14. In 1967, what had been type designated standard as the M16A1 was adopted by the US Army as a whole. The XM16 nomenclature was also replaced by the M16 nomenclature.

The new weapon featured a positive forward assist to help close the bolt when dirty, a chromium plated chamber and bore (not found on the XM16E1 and early M16A1s) to resist corrosion, and an improved gas system with a new bolt buffer designed to reduce the rate of fire on full-auto over the original AR-15/M16 types. These improvements, together with a new field cleaning kit and better maintenance instruction, helped to get rid of many of the reliability problems experienced following the initial mass fielding.

Reliability issues could also be attributed to quality control during Colt's massive expansion in production to keep up with US military demands. So great were the requirements, in large part a product of increased US participation in Vietnam and the arming of US allies in the region with the new rifle, that Harrington and Richardson and the Hydra-Matic Division of General Motors were both contracted between 1968 and 1971 to produce almost 750,000 weapons between them. Colt licensed also the production of M16/M16A1 type rifles to the Philippines, Singapore, and South Korea.

Despite the problems encountered during initial fielding, better training, preventive maintenance, and several design changes, resulted in the weapon that has become the standard issue rifle of the US Army. The weapon, chambered for 5.56x45mm NATO caliber, became the mainstay of the US military for almost 20 years, before being replaced by the imporved M16A2 model.




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