3 Port Muzzle Brake featuring Rugged Rare's Dual Taper Locking System, compatible with all of their rifle and multi-caliber suppressors. This muzzle device is designed for reducing recoil when shooting unsuppressed. The 3 Port Brake has a .30 cal aperture, but the 1/2A-28 variation can be permanently attached to 5.56 14.5a ^2 barrels in order to meet 16a ^2 requirements. *timing shims included