CMMG 30BC40AAB Resolute MK4 | .300 AAC Blackout | 16.1″

The CMMG Resolute MK4 is an assembled partial upper group for AR-15 platform rifles chambered for .300 AAC Blackout. It pairs a 16.1-inch steel barrel with a 1:7″ rate of twist and an M-LOK free‑float handguard finished in Armor Black for a utilitarian appearance. This listing is for the upper assembly only and explicitly does not include a bolt carrier group or charging handle.

Appropriate applications include precision target work from supported positions and medium-range hunting where .300 AAC Blackout performance is desired.

Product Specifications

• The UPC is 810103473393.
• The brand is CMMG.
• The part number and model are 30BC40AAB Resolute MK4.
• The cartridge is .300 AAC Blackout.
• The barrel measures 16.1 inches in length.
• The rate of twist is 1:7".
• The barrel material is steel.
• The barrel finish is matte black.
• The handguard is a M-LOK free‑float design.
• The handguard finish is Armor Black.
• The muzzle threads are 1/2-28.
• The gas system uses a non-adjustable .750 gas block.
• This listing is for a partial upper group.
• A bolt carrier group is not included.
• A charging handle is not included.

The Resolute MK4 upper is a straightforward, component-level option for builders and maintainers who need a serviceable .300 AAC Blackout upper with a free‑float M-LOK handguard and a 16.1″ steel barrel. Its configuration suits shooters assembling a dedicated cartridge-specific upper or upgrading an existing AR-15 lower for hunting or precision work where .300 AAC Blackout ballistics are desired.