MIL-R-63997B, MILITARY SPECIFICATION: RIFLE, 5.56MM: M16A2 (12 DEC 1986) [S/S BY MIL-DTL-63997C]
MIL-R-63997B, MILITARY SPECIFICATION: RIFLE, 5.56MM: M16A2 (12 DEC 1986) [S/S BY MIL-DTL-63997C]., This specification covers a 5.56mm lightweight, air-cooled, gas operated, magazine-fed rifle designed for either three shot automatic burst or semi-automatic fire.