The Adams Arms P1 is the introductory model to the P-Series. This model features ergonomic mid-length MOE handguards and the standard adjustable picatinny railed piston system. The P1 is perfect for any and all AR enthusiasts looking for a self-cleaning piston driven upper that provides superior performance. - SPECS: - Upper Receiver: A4 Flat-Top Forged - Barrel Length: 16 - Barrel Contour: Government - Barrel Material: 4150 Chrome Moly Vanadium Steel - Muzzle Thread Pattern: 1/2-28 - Chrome Lined: No - Barrel Finish: QPQ Melonite / Black Nitride - Twist Rate: 1 in 7 - Chamber: 5.56x45mm NATO - M4 Feed Ramps: Yes - Bolt Carrier: Full-Auto Rated 1-Piece w/Integral Piston Strike Face - Muzzle Device: A2 Flash Hider - Gas System Length: Carbine Short Stroke Piston Operated - Gas Block Diameter: 0.750 - Handguard: Magpul MOE Handguards - Sights: None - Weight: 4.4 lbs