Specifically designed to tame the recoil of the .338 Lapua cartridge. This brake is meant for Larger barrels that are generally required by the 338 Lapua. The diameter is 1.115" and the entire diameter cannot be turned down. The back end will be tapered to meet the barrel diameter. Overall length is 3.3". This brake is pilot bored to .250". It will need to be bored by a gunsmith for the desired caliber. American Precision Arms Gen 1 Fat Bastard 3/4x24 .338 Cal Muzzle Brake G1F34GSS