MPN: 55B8D86-AB


  • Compact Action-Direct Impingement System operates without the need for a buffer and buffer tube
  • Caliber: 5.56 NATO
  • Finish: Armor Black Cerakote
  • Upper Receiver: CMMG Mk4 Dissent Side Charger Upper Receiver - 7075-T6 Aluminum
  • Handguard: 9.6-Inch CMMG Proprietary Handguard
  • M4 Feed Ramps: Yes
  • Muzzle Device: CMMG 5.56 ZEROED Linear Compensator
  • Barrel: 10.5" 1:7 Salt Bath Nitrided 4140 Chrome Moly Steel
  • Muzzle Thread Pattern: 1/2"-28
  • Gas Block: .750" Adjustable Gas Block
  • Gas Tube: Pistol-Length Gas Tube
  • Bolt Carrier Group: Dissent Side Charging Bolt
  • Charging Handle: CMMG Dissent Side Charging Handle (Left)
  • HP and MPI Tested

*This upper receiver assembly has a barrel that is shorter than 16". This upper is only for use on AR pistol lower receivers and NFA registered Short-Barreled Rifle (SBR) lower receivers. All NFA laws apply!


  • Weight: ~4.08 lbs.
  • Length: ~19.1"


  • AR-15 lower receiver


  • 1x CMMG Dissent 5.56 NATO 10.5" MK4 Complete Side Charging Upper
  • 1x CMMG Dissent Side Charging Bolt
  • 1x 1913 Picatinny Rail End Plate


CMMG is known for its versatile and innovative firearms, always made according to its highest standards. Their Dissent line of upper assemblies is incredibly innovative among several other products.

The CMMG Dissent MK4 Complete Side Charging Upper is chambered in 5.56 NATO. This upper assembly has a compact action receiver and a side charging handle instead of the traditional AR charging handle.

Next-Level Versatility

The CMMG Dissent MK4 Complete upper assembly is available in multiple configurations. This specific model has a short 10.5-inch barrel made from 4140 Chrome Moly Steel. The barrel is also threaded with the standard 1/2"-28 and comes equipped with the CMMG 5.56 ZEROED Linear Compensator, which decreases perceived recoil and muzzle rise.

This Dissent upper assembly uses a low-profile adjustable gas system, with the port drilled at pistol length. The barrel and gas block are covered by a 9.6-Inch CMMG proprietary handguard, which has M-LOK slots on both sides and the bottom, along with a full-length Picatinny rail on top for mounting optics.

Unleash Innovation and Efficiency

The Mk4 receiver used on this CMMG Dissent Upper Assembly has a Compact Action Direct Impingement system, eliminating the need for a buffer tube. It lets you install a true folding stock or brace on your firearm. It also comes with the Dissent Side Charging Bolt Carrier Group and a side charging handle.

This upper assembly's bolt and other parts were also HP and MPI tested to ensure the highest quality standards. Therefore, if you want to build a compact AR-style rifle chambered in 5.56, the CMMG Dissent MK4 Complete upper assembly is easily one of the best options.

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  • This Item: CMMG Dissent 5.56 NATO 10.5" MK4 Complete Side Charging Upper
    MSRP: $1,499.95
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