The CMMG Mk4 in .300 Blackout is the premium tier of CMMG's .300 BLK lineup, featuring the Mk4's enhanced components and CMMG's chrome-lined in-house barrel. The mid-length gas system is optimized for supersonic loads. An adjustable gas block handles subsonic cycling. The Mk4 designation means a Geissele trigger and upgraded furniture are standard, creating the most refined factory .300 BLK carbine CMMG produces. Type: Rifle Action: Semi-Automatic Caliber: .300 Blackout Capacity: 30 Year introduced: 2015, USA Weight: 66 oz Overall length: 32.5" Status: Active Intended use: Suppressor Host, Home Defense, Competition