dvr06WTS: Factory CMMG Mk4 8" 300 Blackout M-LOK Upper - Complete (Low Round Count) Complete CMMG MK4 8" 300BO upper , original factory assembly—not a home build. Runs flawlessly both suppressed and unsuppressed. Barrel: 8-inch 4140 Chrome Moly Steel, Salt Bath Nitrided Twist Rate: 1:7 (stabilizes heavy subsonic and light supersonic rounds perfectly) Gas System: Pistol-length direct impingement Handguard: Original factory CMMG free-float M-LOK rail Muzzle Device: Standard A2 flash hider (5/8"-24 threads) BCG & CH: Includes original factory CMMG Bolt Carrier Group (correct legacy stamped markings) and original charging handle. I purchased this new a number of years ago and have only used it a few times. Low round count approximately 150-200, mostly subsonic rounds. $425
