Police Trade-In: Adams Arms Complete Upper Adams Arms Upper Receiver: A3 Flat-Top, Forged Barrel Length: 11.5" 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 Muzzle Device: A2 Flash Hider Gas System Length: Carbine, Short Stroke Piston Operated Gas Block Diameter: 0.750" Handguard: Samson Evolution Extended Modular Rail, Free Float Sights: Adjustable Front & Rear Flip-Up Bolt Carrier Assembly Included: Yes Bolt Carrier Type: 1-Piece w/Integral Piston Strike Face Weight: 4.28 lbs (Without Rail Sections) Chamber & Bore in Very Good Condition Please See photos for Overall Condition