I have a GAP built Armalite AR-10 with a Mike Rock 22" 4R barrel. I have less than 1000 documented rounds. The barrel is in excellent shape and the rifle has holds .5 moa. I am changing calibers, which is my reason for selling. The brake, barrel extension and gas block are all included. The barrel will be shipped from GAP where it will be removed. Please email me with any questions.