M16

The M16 rifle is a family of assault rifles adapted from the ArmaLite AR-15 rifle for the United States military. The original M16 rifle was a 5.56×45mm automatic rifle with a 20-round magazine, and it was introduced in 1964 as the XM16E1, later becoming the M16. The M16A1 replaced the M14 rifle in 1969 and incorporated several modifications, including a bolt-assist and a chrome-plated bore. The M16A2 was adopted in 1983 and fires the improved 5.56×45mm (M855/SS109) cartridge, while the M16A4, introduced in 1997, features a removable carrying handle and a quad Picatinny rail. The M16 has been widely adopted by other armed forces and has a total production of approximately 8 million units, making it the most-produced firearm of its 5.56mm caliber.learn more on wikipedia