CMMG Dissent MK4 Upper .300 Blackout 10.50″ Armor Black

The CMMG DISSENT MK4 upper group is a compact AR-platform upper built for .300 AAC Blackout with a 10.50" barrel and integrated recoil assembly. It uses CMMG's Compact Action and radial delayed blowback technology with a fixed ejector to reduce overall bulk and length versus traditional AR pistol designs. A forward non-reciprocating left-side charging handle allows bolt operation while remaining on target. The upper includes a 1913 Picatinny rail end plate designed to be used in place of a lower receiver buffer tube.

Key Specifications

• The manufacturer is CMMG.
• The model/part is 30BC239AB Dissent MK4.
• The caliber is .300 AAC Blackout.
• The barrel measures 10.50".
• The handguard is a 9.60" M-LOK design.
• The finish is Armor Black.
• The muzzle device is a Zeroed Linear Comp.
• The charging handle is a left side non-reciprocating unit.
• The included end plate is a 1913 Picatinny rail type for buffer-tube replacement use.
• The barrel twist rate is 1:10.

Designed for compact AR-platform builds, the DISSENT MK4 upper combines a shortened footprint with integrated action and recoil components to preserve function in a smaller package. Its left-side charging handle, M-LOK handguard, and linear compensator give builders modular mounting options and practical ergonomics for close-configuration use. Where permitted by law, this upper provides a straightforward, factory-integrated option for those assembling compact AR-platform systems while retaining a focus on reliability and modularity.