The development of the M16A2 rifle was originally requested by the United States Marine Corps as a result of the USMC's combat experiences in Vietnam with the M16 and M16A1. The Marines were the first branch of the US Armed Forces to adopt the M16A2 in the early/mid 1980s with the United States Army following suit in adopting the M16A2 in the late 1980s.

The M-16A2 has been replaced my the M-16A4

Weight     8.5 lb (3.9 kg)
Length     39.5 in (1,003 mm)
Barrel length     20 in (508 mm)
Cartridge     5.56x45mm NATO
Action     Gas-operated, rotating bolt
Rate of fire     800-900 rounds/min, cyclic depending on model
Muzzle velocity     3,200 ft/s (975 m/s) (M16A1)
3,050 ft/s (930 m/s) (M16A2)
Effective range     550 m (600 yd)