The M16 (officially Rifle, Caliber 5.56 mm, M16) is the United States military designation for the AR-15 rifle adapted for semi-automatic, three-round burst and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO cartridge.
The rifle enteredUnited States Army service and was deployed for jungle warfare operations in South Vietnam in 1963, becoming the U.S. military’s standard service rifle of the Vietnam War by 1969, replacing the M14 rifle in that role. The U.S. Army retained the M14 in CONUS, Europe, and South Korea until 1970. Since the Vietnam War, the M16 rifle family has been the primary service rifle of the U.S. armed forces.
The M16 has also been widely adopted by other militaries around the world. Total worldwide production of M16-style weapons since the design’s inception has been approximately 8 million, making it the most-produced firearm of its caliber. As of 2010, the M16 is being phased out in the United States Army, and is being replaced by the M4 carbine, which is itself a shortened derivative of the M16A2. In US Army service, the M16 could be supplemented by the Individual Carbine beginning in 2014 if procurement of a new weapon is attained, if funds allow. All other US services would stay with current M16s and M4 series weapons.
The M16 is a lightweight, 5.56 mm, air-cooled, gas-operated, magazine-fed assault rifle, with a rotating bolt, actuated by direct impingement gas operation. The rifle is made of steel, 7075 aluminum alloy, composite plastics and polymer materials.’
In the early 1960s, the U.S. Air Force’s rifle, the M16, and the Army’s XM16E1, were the first versions of the M16 rifle fielded. Soon the U.S. Army standardized an upgrade of the XM16E1 as the M16A1 rifle, an M16 with a forward assist feature and other improvements requested by the Army. All of the early versions were chambered to fire the M193/M196 cartridge in the semi-automatic and the automatic firing modes. This occurred in the early 1960s, with the Army issuing it in late 1964. Commercial AR-15s were first issued to Special Forces troops in spring of 1964.
ArmaLite sold its rights to the AR-15 to Colt in 1959. The AR-15 was first adopted in 1962 by the United States Air Force, ultimately receiving the designation M16. The U.S. Army began to field the XM16E1 en masse in 1965 with most of them going to the Republic of Vietnam, and the newly organized and experimental Airmobile Divisions, the 1st Air Cavalry Division in particular.
The U.S. Marine Corps in South Vietnam also experimented with the M16 rifle in combat during this period. The XM16E1 was standardized as the M16A1 in 1967. This version remained the primary infantry rifle of U.S. forces in South Vietnam until the end of the war in 1975, and remained with all U.S. military ground forces after it had replaced the M14 service rifle in 1970 in CONUS, Europe (Germany), and South Korea; when it was supplemented by the M16A2. During the early 1980s a roughly standardized load for this ammunition was adopted throughout NATO (see: 5.56x45mm NATO).
The M16A3 is a fully automatic variant of the M16A2, issued within the United States Navy. The M16A2 is currently being supplemented by the M16A4, which incorporates the flattop receiver unit developed for the M4 carbine, and Picatinny rail system. M16A2s are still in stock with the U.S. Army and Marine Corps, but are used primarily by reserve and National Guard units as well as by the U.S. Air Force.
The M16 rifle design, including variant or modified version of it such as the Armalite/Colt AR-15 series, AAI M15 rifle; AP74; EAC J-15; SGW XM15A; any 22-caliber rimfire variant, including the Mitchell M16A-1/22, Mitchell M16/22, Mitchell CAR-15/22, and AP74 Auto Rifle, is a prohibited and restricted weapon in Canada.
The first issues of the rifle generated considerable controversy because the gun suffered from a jamming flaw known as “failure to extract,” which meant that a spent cartridge case remained lodged in the chamber after a bullet flew out the muzzle. According to a congressional report, the jamming was caused primarily by a change in gunpowder which was done without adequate testing and reflected a decision for which the safety of soldiers was a secondary consideration. Due to the issue, reports of soldiers being wounded were directly linked to the M16, which many soldiers felt was unreliable compared to its precursor, the M14, which used stick powder, varying from the M16′s utilization of ball powder.