Radical Firearms RF-15, Semi-automatic, AR Pistol, 300 Blackout, 10.5 HBAR Threaded Barrel, Anodized Finish, Black, Pistol Length Gas System, A2 Flash Hider, MFT Engage V2 Grip, 10 M-LOK Free Float Handguard, 30 Rounds, 1 Magazine RF00148 The Radical Firearms 10.5" HBAR 300BLK AR pistol uses MIL-STD Upper and lower receivers along with their 10" RPR free float rail system for increase accuracy, keeping your hands cool, and giving you plenty of room for accessories.