Coming in with a barrel length of just 6.5 this DISSENT upper group is one of the shortest 5.56mm available to date. Packing all the power of 5.56 in a platform this size doesn't mean giving up usability. A forward non-reciprocating side charger lets you charge the weapon without coming off target and the M-LOK handguard with top picatinny rail provides ample mounting locations for accessories. Style your DISSENT upper group to you with one of seven different Cerakote finishes. Its 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 direct impingement Compact Action, DISSENT upper groups house the entire action and recoil assembly in the upper receiver resulting in less bulk and length than traditional AR pistols. DISSENT Upper groups include a 1913 Picatinny rail end plate to use in place of the lower receiver buffer tube. Specifications for CMMG DISSENT Mk4, 5.56x45mm NATO, 6.5in Upper Receiver: Manufacturer: CMMG Caliber: 5.56x45mm NATO Barrel Length: 6.5 in Barrel Twist Rate: 1-7 Threads per Inch: 1/2x28 Muzzle Device: Zeroed Linear Compensator Fabric/Material: Aluminum Gas Block Journal Size-Diameter: .750 in Gun Rail: M-LOK Gun Make: CMMG Gun Model: CMMG Mk4 Magazine Included: No Package Contents: CMMG DISSENT Mk4, 5.56x45mm NATO, 6.5in Upper Receiver What firearm models does the manufacturer say CMMG DISSENT Mk4, 5.56x45mm NATO, 6.5in Upper Receiver is compatible with? The manufacturer suggests that CMMG DISSENT Mk4, 5.56x45mm NATO, 6.5in Upper Receiver is compatible with CMMG Mk4