page_title: M16 rifle
section_title: Background
hierarchical_section_title: M16 rifle / History / Background
caption_attribution_description: English: ArmaLite AR-15 with flash hider and early 25-round magazine
context_page_description: The M16 rifle, officially designated Rifle, Caliber 5.56 mm, M16, is a family of military rifles adapted from the ArmaLite AR-15 rifle for the United States military. The original M16 rifle was a 5.56mm automatic rifle with a 20-round magazine.
  In 1964, the M16 entered US military service and the following year was deployed for jungle warfare operations during the Vietnam War. In 1969, the M16A1 replaced the M14 rifle to become the US military's standard service rifle. The M16A1 improvements include a bolt-assist, chrome-plated bore and a 30-round magazine.
  In 1983, the US Marine Corps adopted the M16A2 rifle and the US Army adopted it in 1986. The M16A2 fires the improved 5.56×45mm NATO cartridge and has a newer adjustable rear sight, case deflector, heavy barrel, improved handguard, pistol grip and buttstock, as well as a semi-auto and three-round burst fire selector. Adopted in July 1997, the M16A4 is the fourth generation of the M16 series. It is equipped with a removable carrying handle and Picatinny rail for mounting optics and other ancillary devices.
  The M16 has also been widely adopted by other armed forces around the world.
context_section_description: In 1928, a U.S. Army 'Caliber Board' conducted firing tests at Aberdeen Proving Grounds and recommended transitioning to smaller caliber rounds, mentioning in particular the .27. Largely in deference to tradition, this recommendation was ignored and the Army referred to the .30 caliber as "full sized" for the next 35 years. After World War II, the United States military started looking for a single automatic rifle to replace the M1 Garand, M1/M2 Carbines, M1918 Browning Automatic Rifle, M3 "Grease Gun" and Thompson submachine gun. However, early experiments with select-fire versions of the M1 Garand proved disappointing. During the Korean War, the select-fire M2 carbine largely replaced the submachine gun in US service and became the most widely used carbine variant. However, combat experience suggested that the .30 Carbine round was under-powered. American weapons designers concluded that an intermediate round was necessary, and recommended a small-caliber, high-velocity cartridge.
  However, senior American commanders, having faced fanatical enemies and experienced major logistical problems during WWII and the Korean War, insisted that a single, powerful .30 caliber cartridge be developed, that could not only be used by the new automatic rifle, but by the new general-purpose machine gun (GPMG) in concurrent development. This culminated in the development of the 7.62×51mm NATO cartridge.
  The U.S. Army then began testing several rifles to replace the obsolete M1. Springfield Armory's T44E4 and heavier T44E5 were essentially updated versions of the M1 chambered for the new 7.62 mm round, while Fabrique Nationale submitted their FN FAL as the T48. ArmaLite entered the competition late, hurriedly submitting several AR-10 prototype rifles in the fall of 1956 to the U.S. Army's Springfield Armory for testing. The AR-10 featured an innovative straight-line barrel/stock design, forged aluminum alloy receivers and with phenolic composite stocks. It had rugged elevated sights, an oversized aluminum flash suppressor and recoil compensator, and an adjustable gas system. The final prototype featured an upper and lower receiver with the now-familiar hinge and takedown pins, and the charging handle was on top of the receiver placed inside of the carry handle. For a 7.62mm NATO rifle, the AR-10 was incredibly lightweight at only 6.85 lb empty. Initial comments by Springfield Armory test staff were favorable, and some testers commented that the AR-10 was the best lightweight automatic rifle ever tested by the Armory. In the end the U.S. Army chose the T44 now named M14 rifle which was an improved M1 Garand with a 20-round magazine and automatic fire capability. The U.S. also adopted the M60 general purpose machine gun (GPMG). Its NATO partners adopted the FN FAL and HK G3 rifles, as well as the FN MAG and Rheinmetall MG3 GPMGs.
  The first confrontations between the AK-47 and the M14 came in the early part of the Vietnam War. Battlefield reports indicated that the M14 was uncontrollable in full-auto and that soldiers could not carry enough ammunition to maintain fire superiority over the AK-47. And, while the M2 carbine offered a high rate of fire, it was under-powered and ultimately outclassed by the AK-47. A replacement was needed: a medium between the traditional preference for high-powered rifles such as the M14, and the lightweight firepower of the M2 Carbine.
  As a result, the Army was forced to reconsider a 1957 request by General Willard G. Wyman, commander of the U.S. Continental Army Command (CONARC) to develop a .223-inch caliber (5.56 mm) select-fire rifle weighing 6 lb (2.7 kg) when loaded with a 20-round magazine. The 5.56 mm round had to penetrate a standard U.S. helmet at 500 yards (460 meters) and retain a velocity in excess of the speed of sound, while matching or exceeding the wounding ability of the .30 Carbine cartridge.
  This request ultimately resulted in the development of a scaled-down version of the Armalite AR-10, named ArmaLite AR-15 rifle. In the late 1950s, designer Eugene Stoner was completing his work on the AR
caption: ArmaLite AR-15
exif: {}