MODULAR ACTION WRENCH HEADS **DO NOT use SAC action wrench head without proper SAC bumpers. Bumpers are only available with the Modular Action Wrench Kit** The SAC Modular Action Wrench Heads are designed to precisely fit your action to ensure proper torque and to protect your action from any damage. Made from 4140 Alloy Steel and heat treated to HRC 32 with a black nitride finish. With a low cost, the action wrench heads are quick and tool-less allowing the end user to have one tool that can work on most actions, without compromise. Actions that do not utilize a counterbore on the barrel face will come with a short front bumper to properly locate it in the action. Sim Mfg: Short Action Customs