The M16 rifle is a family of military rifles derived from the ArmaLite AR-15 rifle. A 5.56 mm rifle, it was designed in 1959 and later entered U.S military service in 1964, being used for operations in the Vietnam War. Since then, it has become widely used by armed forces around the world. With over 8 million M16’s made already, it is the most-produced 5.56 mm firearm.
The M16A4 is the fourth generation in the M16 series. This firearm features a muzzle compensator in place of the flash suppressor to manage recoil as well as a heavier and/or a free-floating barrel to increase accuracy. The M16A4 was the standard infantry rifle for the U.S Marine Corps until the M4 carbine replaced it in 2015. It is now used by support and non-infantry Marines.