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AR Parts Notice - State/local restrictions may apply in CT, DC, IL, MA, NJ, NY, or WA. Customers must review our Shipping Policy prior to ordering.


The 5.7x28mm personal defense cartridge has found home with the purposefully designed 6.5” DISSENT® upper group. This DISSENT upper group comes complete with BCG, lower receiver 1913 picatinny rail end plate, and the choice of seven Cerakote finishes to make it uniquely you. All you need is a Mk4/mil-spec AR15 lower receiver or CMMG® Mk57 lower receiver.

It’s no secret that pistol stabilizing braces have been a target for scrutiny over the years, and those that enjoy building their own AR pistols have wondered what will come out of all the uncertainty. DISSENT is our answer. Utilizing our patent pending Compact Action and Radial Delayed Blowback technology, DISSENT upper groups house the entire action and recoil assembly in the upper receiver resulting in less bulk and length than traditional AR pistols. The forward non-reciprocating side charger allows for quick bolt operation without coming off target.

DISSENT Upper groups include a 1913 Picatinny rail end plate to use in place of the lower receiver buffer tube.


Lifetime Quality Guarantee

We aim to please, that’s why every CMMG product is backed by our Lifetime Quality Guarantee against material and workmanship defects. Learn More.


*NFA Rules May Apply

6.5" DISSENT upper groups are made to be used in a pistol configuration, using a pistol upper in conjunction with a stock or stabilizing brace on the lower receiver may make your DISSENT and SBR and subject to NFA rules. Learn more about NFA rules.

Technical Specifications

Caliber 5.7x28mm
Operating System Compact Action-Radial Delayed Blowback
Barrel Length 6.5
Barrel Twist 1:9
Barrel Contour MT
Barrel Material 4140CM, SBN
Barrel Twist 1:9
Muzzle Device CMMG ZEROED Linear Compensator
Muzzle Thread 1/2 x 28
Gas Port Location N/A
Gas Block N/A
Upper Receiver DISSENT 7075 T6 Aluminum
Hand Guard CMMG 5.5" Proprietary
Finish Cerakote
Charging Handle DISSENT Side Charger - Left
Buffer Type N/A
Receiver Extension 1913 Picatinny Rail End Cap


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