The Radical Firearms RPR 16" SOCOM 5.56mm AR rifle uses MIL-STD Upper and lower receivers along with our 15" RPR free float rail system for increased accuracy, keeping your hands cool and giving you room for accessories. Featuring a B5 Grip Type 23 pistol grip; B5 Bravo Stock with 6 positions; carbine MIL-STD buffer tube; A2 flash hider and a Chrome Moly Vanadium threaded barrel.