The CMMG RESOLUTE MK4 Upper Group is a 6mm ARC AR15-pattern upper receiver built around a 16.1-inch barrel for precise, high-performance direct-impingement shooting. This Mk4 configuration pairs with standard AR15 lowers and comes packaged as a complete upper group with included ZEROED accessories, so the assembly is ready to take to the range.

Key features

• 16.1-inch 6mm ARC barrel with 1:7.5 twist for stable, consistent bullet stabilization
• Rifle-length direct-impingement gas system with a 0.750 non-adjustable gas block
• Billet 6061 T6 aluminum upper receiver mated to a CMMG EML15 M-LOK hand guard
• 416SS SBN barrel for durability and reliable long-term performance
• CMMG ZEROED muzzle brake and ZEROED charging/dust-cover accessories included
• Muzzle threads: 5/8 x 24 for common brake and suppressor mounting options

Built for the 6mm ARC platform and designed to work with standard AR15 lowers, this RESOLUTE MK4 upper group brings a complete, zeroed accessory package in a ready-to-build format.