Full Sail Brake, or the "FSB." The purpose of this brake is found in the name. Just like the sails on a ship this brake pulls the muzzle away from the shooter. The design was set up to reduce felt recoil and keep the muzzle static. As the pressure and gas travel through the muzzle all the force is met by a series of three proprietary walls and angles to mitigate gun travel. Another feature that we have added to the FSB is the rear locking nut that is threaded for a left-hand twist. This rear locking nut allows for the FSB to be perfectly positioned to the barrel without having to use a crush washer. The FSB is ideal for any competition shooter that needs to be on target for multiple shots or for the recreational shooter that just wants to enhance their overall shooting experience. 22cal - 1/2x28 threads. 6.5 - 5/8x24 threads. 30cal - 5/8x24 threads. 9mm - 1/2x28 threads.