MAC IX 9mm Luger 6.50" Black Anodized Threaded Barrel & Receiver w/Picatinny Rail, M-LOK Handguard, Black Polymer Tailhook Retractable Brace The MAC IX is a modular 9mm PCC built for reliability and performance. It features a proven direct blowback system for minimal recoil and fast follow-up shots; accepts MP5-style magazines for dependable, familiar feeding; monolithic upper, full-length Picatinny rail and M-LOK handguard,