M16A1

☀The M16 rifle, officially designated Rifle, Caliber 5.56 mm, M16, is a United States military adaptation of the Armalite AR-15 rifle.[8][9][10][n 1] The original M16 was a select-fire, 5.56×45mm rifle with a 20-round magazine.

In 1964, the M16 entered American military service and the following year was deployed for jungle warfare operations during the Vietnam War.[1] In 1969, the M16A1 replaced the M14 rifle to become the U.S. military's standard service rifle.[13][14] The M16A1 improvements include a bolt-assist, chrome plated bore and a new 30-round magazine.[1] In 1983, the USMC adopted the M16A2 rifle and the U.S. Army adopted it in 1986. The M16A2 fires the improved 5.56×45mm NATO (M855/SS109) cartridge and has a new adjustable rear sight, case deflector, heavy barrel, improved handguard, pistol grip and buttstock, as well as a semi-auto and three-round burst only fire selector.[15][16] Adopted in 1998, the M16A4 is the fourth generation of the M16 series.[17] It is equipped with a removable carrying handle and Picatinny rail for mounting optics and other ancillary devices.[17]

The M16 has also been widely adopted by other militaries around the world. Total worldwide production of M16s has been approximately 8 million, making it the most-produced firearm of its 5.56 mm caliber.[18] The U.S. Army has largely replaced the M16 in combat units with the shorter and lighter M4 carbine,[19]and the U.S. Marine Corps approved a similar change in October 2015.[20]

Contents
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 * 1History
 * 1.1Background
 * 1.2Adoption
 * 2Reliability
 * 3Design
 * 3.1Barrel
 * 3.2Recoil
 * 3.3Sights
 * 3.4Range and accuracy
 * 3.5Terminal ballistics
 * 3.6Magazines
 * 3.7Muzzle devices
 * 3.8Grenade launchers and shotguns
 * 3.9Riot Control Launcher
 * 3.10Bayonet
 * 3.11Bipod
 * 4NATO standards
 * 5Predecessors
 * 5.1Pre-Production ArmaLite AR-15
 * 5.2ArmaLite AR-15 (Colt Models 601 & 602)
 * 6Variants
 * 6.1M16
 * 6.2XM16E1 and M16A1 (Colt Model 603)
 * 6.3M16A2
 * 6.4M16A3
 * 6.5M16A4
 * 6.6Summary of differences
 * 7Derivatives
 * 7.1Colt Model 655 and 656 "Sniper" variants
 * 7.2XM177
 * 7.3Colt Model 733
 * 7.4M231 Firing Port Weapon (FPW)
 * 7.5Mk 4 Mod 0
 * 7.6Mark 12
 * 7.7M4 carbine
 * 7.8Heckler & Koch HK416
 * 7.9Diemaco C7 and C8
 * 7.10Others
 * 8Production and users
 * 8.1Users
 * 8.2Former users
 * 9See also
 * 10Notes
 * 11References
 * 12Further reading
 * 13External links