Muzzle brakes come in various designs. Some are intergral too the barrel while others are seperate pieces that either screw, weld/braze/soldered, pinned or permenantly attached. If its removalable then only limiting factor would be matching thread pitch and size too the new brake. Usually permenant brakes are installed on barrels under 16" too make them rifle legal. Good example was the AK's imported several years ago. Barrel with permanent attached muzzle brakes length becomes that of barrel plus the muzzle brake.