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 […]
A lot of open-source information is available from the military on the M4 and its variants—the M4A1, MK18, and MK12 Special Purpose Rifle (SPR)—including
US Army M4A1 Carbine isolated on a white background, studio shot