The "action wrench" fits in a regular bench vise. The bottom part of the action wrench is paced in the bench vise and the jaws are tightened down firmly. the action is placed into the lower half of the wrench, and top part of the wrench is then screwed down over the action thus holding it firmly. Then the barrel nut wrench is used to loosen the nut, and the current barrel can be unscrewed. Reverse the procedure and presto! You have a new caliber. No need to have a barrel vise.
