The Just Right Carbine 9mm is a reliable, blowback-operated semi-automatic rifle. While it will take AR trigger groups, stocks, pistol grips and fore-ends, one look at the carbine will tell you it is not designed around the AR receiver. The JR Carbine is a straight-blowback carbine designed to feed from the Glock magazine. For any questions or further information, please call Hammond Cabelas at (219) 845 9040.