DPMS Kitty Kat C7 5.56x45mm NATO 7.5 inch Upper Receiver One Size. 56 NATO with a 1:7 twist rate M4 barrel extension and a pistol-length gas system. The nitrided barrel is finished off with a 4in knurled tube free-float handguard R-marked front sight gas block and an A2 flash hider. Upper: Forged 7075-T6 C7 AR upper is machined to MIL-SPECS and hard coat anodized. Uppers include forward assist dust cover and A1 rear sight appature. Bolt Carrier Group: Shot-peened mil-spec Carpenter 158 steel bolt. Gas Key Hardened to USGI Specifications fastened with Grade 8 screws and Staked Per Mil-Spec. Carrier is 8620 steel M-16 full auto profile and is chrome lined and phosphate coated. Specifications for DPMS Kitty Kat C7 5.56x45mm NATO 7.5 inch Upper Receiver: Manufacturer: DPMS Caliber: 5.56x45mm NATO Barrel Length: 7.5 in Barrel Profile: Heavy Gas System Length: Pistol Length Barrel Twist Rate: 1-7 Finish: Hardcoat Anodized Fabric/Material: 7075 T6 Aluminum Gas Block Journal Size-Diameter: .750 in Handguard Length: 4 in Barrel Material: Chrome Moly Vanadium Package Contents: DPMS Kitty Kat C7 5.56x45mm NATO 7.5 inch Upper Receiver DPMS DP51655155946: Kitty Kat C7 5.56x45mm NATO 7.5 inch Upper Receiver One Size