This Complete Upper Group from CMMG (CMMG part no. 22B820FAB) is part of the Resolute MK4 rimfire AR platform, chambered in .22 LR with a 16.1-inch barrel finished in black, ready to install on a compatible AR-15 lower.

Key Specifications

• Chambers .22 LR.
• Barrel measures 16.1 inches.
• Finished in black.
• Sold as a complete upper group, ready to install.
• Part of CMMG’s Resolute MK4 rimfire AR platform line.

Frequently Asked Questions

Will this fit a standard 5.56 AR-15 lower? The Resolute MK4 rimfire platform is designed to mate with standard AR-15-pattern lowers, but confirm magazine and bolt compatibility since .22 LR uses dedicated rimfire components.

Does this include a bolt carrier group and charging handle? Yes, it’s sold as a complete upper group, which includes the barrel, handguard, and the rimfire-specific bolt and charging handle needed to function.

Buy the CMMG Resolute MK4 .22 LR Complete Upper Group, Black

Add a dedicated rimfire training upper to your AR-15 with this CMMG Resolute MK4 .22 LR complete upper. It ships fast from our Lubbock, Texas gun shop, and our AR-15 uppers selection has more AR-15 upper receivers.