AIM Sports Inc Complete AR 10.5in .300 Blk 11in Pistol Length Gas Upper w/Nitride BCG Black Large Black Large. 300 Blackout complete pistol upper receiver assembly is the perfect addition for your complete lower receiver assembly. The upper features a factory installed 10.5" 4150 CMV barrel with nitride finish. The upper receiver features fully installed forward assist and dust cover. Specifications for AIM Sports Inc Complete AR-15 .300 Blk 10.5in Pistol Length Gas Upper w/Nitride BCG: Manufacturer: AIM Sports Inc Caliber: .300 AAC Blackout Barrel Length: 10.5 in Finish: Nitride Color: Black Gun Make: AR Platform Features of AIM Sports Inc Complete AR-15 .300 Blk 10.5in Pistol Length Gas Upper w/Nitride BCG 11" Barrel 4150 Chrome Moly Vanadium Steel A2 muzzle brake and crush washer Pistol length gas tube and low profile gas block Mil-Spec Forged 7075-T6 complete Upper with dust cover and forward assist Bolt Carrier Group 8620 steel and bolt is 9310 tool steel with a Nitride finish Package Contents: AIM Sports Inc Complete AR-15 .300 Blk 10.5in Pistol Length Gas Upper w/Nitride BCG AIM Sports Inc AR5CUB12: Complete AR 10.5in .300 Blk 11in Pistol Length Gas Upper w/Nitride BCG Black Large AR5CUB12 Black Large