The barrel bushing lock is the spring loaded small pin that is located in front of the FSB. (Front sight base) This bushing lock holds the slant muzzle break (PolyTech AKS-762) or muzzle nut (PolyTech AK47/S Legend Series) in place. To remove the break, push in on the barrel bushing lock and turn the break/nut clock-wise. The bushing lock is spring-loaded held in place by the front sight base pin. To remove, tap-out the FSB pin using a punch. When installing the new barrel bushing lock, be sure to have the notched side up to accept the FSB pin. It is best practice to install a new spring (item# 70-01-38) while you have AK47 Muzzle Break disassembled.