Radical Firearms AR-15 RPR 5.56 NATO 16in Black Melonite Semi Automatic Modern Sporting Rifle - 30+1 Rounds - The Radical Firearms 16in Socom 5.56mm AR rifle uses MIL-STD Upper and lower receivers along with our 15in RPR free float rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories. The M4 Grip and M4 Stock provide a comfortable hold on the rifle whether prone or upright. Regardless if its your first or fiftieth, a Radical Firearms AR rifle will not disappoint!