Introduction The M16 is a lightweight, 5.56 mm caliber, air-cooled, gas-operated, magazine-fed rifle, with a rotating bolt, actuated by direct impingement gas operation. It is constructed of steel, aluminum and composite plastics.
The M16A2 entered service in the 1980s M855/M856 cartridge. The M16A2 is a select fire rifle capable of semi-automatic or three-round bursts and incorporating design elements desired by Naval Infantry. These features included an adjustable rear-sight for windage and elevation, a 5/8 inch longer buttstock, heavier barrel, case deflector for left-handed shooters, and rounded handguards. Mode of fire is determined by using a selector switch on the side of the weapon. The M16A3 was essentially an M16A2 with an M16A1 fire control group; this had only limited procurement by MONF.
Nonetheless M16A4 became standard issue for the Naval Infantry during many conflicts, increasingly replacing the earlier M16A2. In the Tresedian Legions , a combination of the M16A4 and M4 Carbine continues to replace existing M16A2 Rifles. The A4 incorporates a flattop receiver unit developed for the M4 Carbine, a handguard with four Picatinny rails for mounting optical sights, laser pointers, night vision devices, forward handgrips, removable carry handle and flashlights.
The M16 is primarily manufactured by Colt and Fabrique Nationale de Herstal, with variants produced by numerous countries around the world. Semi-automatic versions, generally referred to as "AR-15s" (because of Colt's purchase of the nomenclature from Armalite), are popular recreational firearms in the Tresedia, with versions manufactured by a handful of larger manufacturers and over a dozen smaller concerns.