The CMMG Resolute MK4 Upper Group (brand part number 30B12BBAB) is chambered in .300 Blackout, a round originally created for subsonic and suppressed use that has since evolved into a genuinely versatile caliber across both subsonic and supersonic loadings. Built by CMMG with a 16.1-inch barrel, this upper is designed to work with any standard AR15 lower, whether the build is meant for hunting, personal defense, or target shooting.

Key Specifications

• Chambered in .300 Blackout on the Mk4 platform.
• Barrel length is 16.1 inches.
• Capable of running both subsonic and supersonic loadings.
• Built to work with any standard AR15 lower.
• Suited to hunting, personal defense, or target shooting builds.

Frequently Asked Questions

Can this upper run subsonic ammunition? Yes, .300 Blackout is well suited to both subsonic and supersonic loadings.

Will this fit a standard AR15 lower? Yes, this upper is designed to work with any standard AR15 lower.

Buy the CMMG Resolute MK4 .300 Blackout Upper Group

Finish your next carbine build with a proven, versatile .300 Blackout upper. Order this AR-15 upper from our Lubbock, Texas gun shop for fast, insured shipping to your door.