Overview
The M4A1 is a fully automatic variant of the M4 carbine, a shorter and lighter variant of the M16. It went into service in 1994 to replace the M16 in certain roles. The M4A1 trigger group operates on either Safe, Semi-Automatic, or Fully Automatic settings. Cartridges are the 5.56x45mm (.223) NATO cartridge that is magazine fed. Firing is achieved via a direct impingement gas operating system. It is primarily used by special operations.
