CMMG 55B8D86AB Dissent MK4 | 5.56 NATO | 10.50 in Upper

The CMMG Dissent MK4 upper group is a compact AR-platform upper that houses the action and recoil assembly in the upper receiver using CMMG’s Compact Action and radial delayed blowback system. This configuration reduces overall bulk and length compared with traditional AR pistols and is purpose-built for compact AR pistol builds and short-range competition or range training. The forward non-reciprocating left-side charging handle allows bolt operation without removing the sight picture. This listing is for the upper assembly only and includes a 1913 Picatinny rail end plate to use in place of a lower receiver buffer tube.

Product Specifications

• The manufacturer is CMMG.
• The model is Dissent MK4.
• The manufacturer’s part number is 55B8D86AB.
• The caliber is listed as .223 REM/5.56 NATO.
• The barrel measures 10.50 in.
• The barrel finish is Black.
• The rate of twist is 1:7.
• The handguard type is a 9.60 in M-LOK.
• The handguard finish is Armor Black.
• The overall finish type is Armor Black.
• The charging handle is a Left Side non-reciprocating design.
• The muzzle device is a Zeroed Blast Comp.
• The end plate is a 1913 Picatinny rail.
• The product fits AR-Platform configurations.
• The UPC is 810097509276.

Designed for builders who prioritize compact handling and straightforward operation, the Dissent MK4 upper delivers a full upper assembly with integrated radial delayed blowback operation, left-side charging convenience, and a modular 9.60 in M-LOK handguard for common accessory layouts. Its configuration is well suited to AR pistol projects and short-range sport or training use where reduced overall length and on-target charging are desirable.