Originally created for use in subsonic/suppressed applications .300 BLK has evolved into a very capable caliber available in a variety of subsonic and supersonic loadings. Whether it’s hunting personal defense or target shooting this .300 BLK RESOLUTE Upper Group is just the thing to finish your next carbine build. This upper is designed to work with any standard AR15 lower. 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 .308 – Platform: Mk4 – Caliber: .300 BLK – Operating System: Direct Impingement – Barrel Length: 16.1 – Barrel Twist: 1:7 – Barrel Contour: MT – Barrel Material: 4140CM SBN – Muzzle Device: CMMG ZEROED Muzzle Brake – Muzzle Thread: 5/8 x 24 – Gas Port Location: Carbine – Gas Block: 0.750 Non-Adjustable – Upper Receiver: Billet 6061 T6 Aluminum – Hand Guard: CMMG EML15 M-LOK – Finish: Cerakote Standard – Charging Handle: CMMG ZEROED Ambi – Weight: 4.1 lbs – Length: 25