M16A4 (ID 9.29)

The M16A4 is the fourth generation of the M16 series. The iron sight/carrying handle assembly on the M16A2/M16A3 upper receiver, was replaced by a MIL-STD-1913 "Picatinny railed" flat-top upper receiver for mounting aiming optics or a removable iron sight/carrying handle assembly. The M16A4 rear aperture sights integrated in the Picatinny rail mounted carry handle assembly are adjustable from 300 m (330 yd) up to 600 m (660 yd), where the further similar M16A2 iron sights line can reach up to 800 m (870 yd). The FN M16A4, using safe/semi/three-round burst selective fire, became standard issue for the U.S. Marine Corps.