CMMG Banshee MK4, Semi-automatic Pistol, 300 Blackout, 8 Barrel, Cerakote Finish, Armor Black, 30 Rounds, 1 Magazine 30A240F-AB Compact and capable, .300 BLK was designed to be right at home in AR15-pattern firearms like the CMMG Mk4 platform. Originally created for optimum performance in subsonic, suppressed, and short-barrel applications, .300 BLK, in supersonic ammo loadings, has evolved into a popular competitor to other intermediate cartridges like 7.62x39. No matter what the application is, this BANSHEE is built to fit the bill.