The alexander arms ar15 standard rifle upper was developed to function as the ideal item for anybody trying to find an exceptional option.With a black cerakote finish, and a m-lok handguard, you could get this upper to complete your build.Receiver Finish: Black CerakoteType: CompleteCaliber: 50 BeowulfSights: None, Optic ReadyBarrel Length: 16"Twist: 1:8"Handguards: M-LOKHandguard Finish: BlackBarrel Length Range: 16" to 16.99"