The CMMG Resolute MK4 is a semi-automatic rifle chambered in 5.56 NATO / .223 Remington, running a direct impingement operating system. At 6.4 lbs and 32.25 inches overall, it sits in the lighter end of the 16-inch AR market without cutting corners on materials. 
 

Key Specifications 

• Model: CMMG Resolute MK4 
• Caliber: 5.56 NATO - .223 Remington 
• Operating System: Direct Impingement 
• Barrel Length: 16.1 inches 
• Barrel Twist: 1:7 
• Capacity: 30 rounds (Magpul PMAG) 
• Weight: 6.4 lbs 
• Overall Length: 32.25 inches 
   

Detailed Features 

The barrel is 4140CM steel with a Cerakote finish, designed for durability across sustained use. A CMMG Zeroed Muzzle Brake controls recoil and muzzle rise during rapid fire. The mid-length gas system cycles smoothly with a range of ammunition types. 
 
The upper receiver is billet 6061 T6 aluminum; the lower is forged 7075 T6, a combination that keeps weight down while maintaining structural integrity. Ambidextrous charging handle and safety selector accommodate left-handed shooters without requiring aftermarket modifications.

The Resolute MK4 in Midnight Bronze attracts mixed but generally positive feedback. Build quality is the first thing owners mention. The materials and fit are consistently rated well, and the Midnight Bronze finish gets called out specifically for its appearance at the range.

Accuracy holds up at distance. Precision-oriented shooters report reliable groups across varied range sessions and note the rifle stays consistent under extended use. Ergonomics come up favorably: the adjustable stock and grip suit different shooter builds, and most users find the controls intuitive from the first session.

Customization is a common topic. Owners appreciate that standard AR accessories fit without modification, making it easy to add optics, lights, or aftermarket furniture.

Price conversations are split. Many buyers feel the construction quality and features justify what CMMG charges; others run comparisons against similar-spec rifles and feel the gap is debatable. Reliability under adverse conditions and extended use gets strong marks from most owners. Customer service experiences vary. Positive interactions with warranty claims sit alongside reports of slower response times or parts availability issues.