6315AE is a collaboration between Allen Engineering and FCD. Threaded for 1/2 x 28 (internal) and M22 x 1 (external), 6315AE is compatible with all Allen Engineering .223 sound suppressors such as AEM2 AEM3, AEM4, and AEM5 (except for direct thread models, such as M4 and M24) Most folks are familiar with the iconic Mk12 brake. We’re a big fan of the brake, it’s one of the least obnoxious brakes we tested, our own 1215KM (Keymo), 1215XE (Xeno), 1215RF (Plan B compatible) are based on the Mk12 brake design.