Designed to be a flat shooting round at medium to long ranges 6.5 Grendel offers efficient ballistic performance native to many 6.5mm bullet designs. The upside here is that this RESOLUTE Mk4 Upper Group in 6.5 Grendel is built on the Mk4 platform and works with any standard AR15 lower group. 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 6.5mm - Platform: Mk4 - Caliber: 6.5 Grendel - Operating System: Direct Impingement - Barrel Length: 16.1 - Barrel Twist: 1:8 - Barrel Contour: MT - Barrel Material: 416SS SBN - Muzzle Device: CMMG ZEROED Muzzle Brake - Muzzle Thread: 5/8 x 24 - Gas Port Location: Rifle - 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: 4.3 lbs - Length: 25