The Radical Firearms FP10.5-5.56M4-10RPR is a complete AR 15 chambered in 5.56mm NATO. This is a fully Mil-Spec AR-15 pistol with precision machined upper and lower receivers. It starts with a 4140V Chromoly Vanadium Steel M4 Barrel that is Melonite treated for a harder-than chrome finish! The Mil-Spec M-16 BCG is high pressure tested, magnetic particle inspected and melonite finished to ensure flawless performance in the field. It features a free float Radical Firearms 10" RPR (Radical Parallelogram Rail) that is M-LOK compatible and has a full length picatinny top rail.- CALIBER .223 REM/5.56MM NATO- MAGAZINE (1) with 30rd capacity- BARREL 10.5" 4140V CMV, M4 Profile Barrel, Threaded 1/2x28 TPI, A2 Flash Hider, 1:7" Twist with Black Melonite Finish- RECEIVERS Forged 7075 T6, Type III Anodizing, M4 MIL-STD- HANDGUARD 10" Radical Firearms Free Float RPR M-LOK- BRACE Pistol Tube