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. Featuring quick deploy RIPBRACE; EML handguards with full-length M-LOK slots on both sides and the bottom of the handguard as well as M-LOK between the top Picatinny rail sections and Mk4 ZEROED parts. Includes 30rd Magpul PMAG.