The RCBS Trim Mate Primer Pocket Uniformer is designed to ensure that primer pockets are cut to the correct SAAMI depth specifications. It also cleans out built up carbon residue from previous firings and squares the bottom of the primer pocket with respect to the case head. This step is important as variations in the seating depth of the primer can change how the firing pin strikes the primer producing inconsistent ignition. This tool features a sharp carbide cutter, which ensures that primers will seat perfectly every time. All RCBS equipment is made in the U.S. and 100% reliable.