Dead Air Xemax Muzzle Brake .338 Cal. M18X1Dead Air Xemax Muzzle Brake . 338 Cal. M18X1 Designed for . 338 caliber platforms; Features Xeno Mounting Technology for precise bore alignment and repeatability; Single port design minimizes ground dust and reduces felt recoil; Optimized for bolt action rifles and big bore MSRs; Compatible with Nomax 33 and Primal silencers (with Xemax adapter); Includes shims for proper timing; Constructed for durability and long lasting suppressor performance;