Looking to build the ultimate 9mm pistol caliber carbine? We have you covered! Utilizing our Radial Delayed Blowback operating system not only does this upper create one of the softest shooting 9mm PCCs with style that is unmistakably CMMG this upper group is designed to work with a number of different lower receivers. From standard AR15 lowers (when used with AR 9 conversion mags) to any of our pistol magazine lowers (Mk9 MkGs and Mk17) you can build your next PCC exactly how you imagine. Available in six different Cerakote finishes all CMMG Upper Groups come complete with bolt carrier group and ZEROED accessories including: - ZEROED AR15 Polymer Dust Cover - ZEROED AR15 Ambi Charging Handle - ZEROED Muzzle Brake 9mm - Platform: Mk4 Mk9 Mk17 MkGs - Caliber: 9mm - Operating System: Radial Delayed Blowback - Barrel Length: 16.1 - Barrel Twist: 1:10 - Barrel Contour: MT - Barrel Material: 4140CM SBN - Muzzle Device: CMMG ZEROED Muzzle Brake - Muzzle Thread: 1/2 x 28 - Upper Receiver: Billet 6061 T6 Aluminum - Hand Guard: CMMG EML15 M-LOK - Finish: Cerakote Standard - Charging Handle: CMMG ZEROED Ambi - Weight: 4.0 lbs - Length: 25.3