Sons of Liberty Gun Works M4-89 5.56 NATO AR-15 Upper - 10.5"

Specifications: Barrel: Sons of Liberty Gun Works 4150CoMOV 1:7 MPI HPT Barrel Barrel Steel: 4150 CrMoV (Chrome Moly Vanadium per MIL-B-11595E) Twist Rate: 1/7 Twist Six Groove Thread Pitch: 1/2-28 Threaded Muzzle Gas Block: .750 Gas Block Journal with appropriately sized gas port Barrel Finish: QPQ Corrosion Resistant Finish Barrel Extension: QPQ coated M4 Feed Ramp Extension High Pressure (proof) Tested (HPT) Magnetic Particle Inspected (MPI) Twist Rates & Thread Pitches will match caliber. Match-grade firearms will have 416 Stainless Steel barrels. Carbine Gas System A2 muzzle device