This Ruger Muzzle Brake System includes a removable, radial-port muzzle brake that significantly reduces felt recoil. For times when the brake is not preferred, it may be replaced by the included dynamically-matched muzzle weight. Switching between the brake and the weight will not change the bullet's point of impact for a particular load. The included thread protector may be used if neither the brake nor the weight is desired. Fits .30 caliber rifles with 1/2"-24 muzzle threads. Does NOT fit Gunsite Scout Rifle.