ABC RIFLE COMPANY AR-15 .223 Remington/5.56x45mm NATO 16in Barrel 12in Quad Rail Handguard Upper Receiver w/Charging Handle 1-8 Twist 1/2x28 A2 Style. The 16in 4150 CMV barrel with a 1:8 twist and A2 birdcage flash hider delivers reliable accuracy and muzzle control. Built with a 6061-T6 aluminum barrel nut locking steel jam nut .750 gas block and 9in stainless carbine gas tube this upper ensures smooth operation. Finished with an MPI-tested nitride BCG forged milspec charging handle forward assist and ejection port coverits built to handle anything you throw at it. Specifications for ABC RIFLE COMPANY AR-15 .223 Remington/5.56x45mm NATO 16in Barrel 12in Quad Rail Handguard Upper Receiver w/Charging Handle: Manufacturer: ABC RIFLE COMPANY Caliber: .223 Remington 5.56x45mm NATO Barrel Length: 16 in Barrel Twist Rate: 1-8 Threads per Inch: 1/2x28 Muzzle Device: A2 Style Muzzle Brake Color: Black Gun Model: AR-15 Handguard Length: 12 in Gun Type: Rifle Gun Make: AR Platform Gas Block Journal Size-Length: .750 in Last Chance: Yes Package Contents: ABC RIFLE COMPANY AR-15 .223 Remington/5.56x45mm NATO 16in Barrel 12in Quad Rail Handguard Upper Receiver w/Charging Handle What firearm models does the manufacturer say ABC RIFLE COMPANY AR-15 .223 Remington/5.56x45mm NATO 16in Barrel 12in Quad Rail Handguard Upper Receiver w/Charging Handle is compatible with? The manufacturer says that ABC RIFLE COMPANY AR-15 .223 Remington/5.56x45mm NATO 16in Barrel 12in Quad Rail Handguard Upper Receiver w/Charging Handle is compatible with AR-15ABC RIFLE COMPANY UPPER15-QR12: AR-15 .223 Remington/5.56x45mm NATO 16in Barrel 12in Quad Rail Handguard Upper Receiver w/Charging Handle 1-8 Twist 1/2x28 A2 Style Muzzle Brake Nitride Black