CMMG Dissent Mk3 .308 Winchester 20 inch Upper Receiver 1-10 Twist 5/8 x 24 CMMG ZEROED Muzzle Brake Cerakote/Hard Coat Anodized 38B830C-HCA. 308 cartridge the CMMG Mk3 platform is the larger frame foundation for cartridges such as .308 Win. This...