<P> In 1964 , the M16 entered U.S. 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 U.S. military 's standard service rifle . The M16A1 improvements include a bolt - assist , chrome plated bore and a new 30 - round magazine . In 1983 , the U.S. Marine Corps 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 . Adopted in 1998 , 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 . </P>
<P> In 1964 , the M16 entered U.S. 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 U.S. military 's standard service rifle . The M16A1 improvements include a bolt - assist , chrome plated bore and a new 30 - round magazine . In 1983 , the U.S. Marine Corps 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 . Adopted in 1998 , 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 . </P>
when was the 30 round m16 magazine introduced
when was the 30 round m16 magazine introduced
1969
1969