CMMG DISSENT Upper Receiver Mk4 300BLK 10.5in 1-7 Twist 5/8x24 Thread Zeroed Linear Compensator Tungsten 30BC239-TNG. 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...