CMMG DISSENT Upper Receiver Mk4 300BLK 10.5in 1-7 Twist 5/8x24 Thread Zeroed Linear Compensator Armor Black. 5 300BLK DISSENT so we decided to take it and crank it up to 11... or how about 10.5? Giving you improved ballistics and an even more suppressor friendly length this all new length 300BLK upper is just the ticket to finish your 300BLK AR pistol build. 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. 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. Specifications for CMMG DISSENT Mk4 300BLK 10.5in Upper Receiver: Manufacturer: CMMG Caliber: .300 AAC Blackout Barrel Length: 10.5 in Barrel Twist Rate: 1-7 Threads per Inch: 5/8x24 Muzzle Device: Zeroed Linear Compensator Fabric/Material: Aluminum Gun Rail: M-LOK Gun Make: CMMG Gun Model: CMMG Mk4 Magazine Included: No Package Contents: CMMG DISSENT Mk4 300BLK 10.5in Upper Receiver What firearm models does the manufacturer say CMMG DISSENT Mk4 300BLK 10.5in Upper Receiver is compatible with? The manufacturer suggests that CMMG DISSENT Mk4 300BLK 10.5in Upper Receiver is compatible with CMMG Mk4CMMG 30BC239-AB: DISSENT Upper Receiver Mk4 300BLK 10.5in 1-7 Twist 5/8x24 Thread Zeroed Linear Compensator Armor Black