Primer pocket uniformers are designed to ensure that primer pockets are cut to the correct SAAMI depth specifications, cleaning out built up carbon residue from previous firings and squaring 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 preset stop collar set to SAAMI specifications.Specifications and Features:The primer pocket uniformer is only used on rifle brass. If it's used on pistol brass the pocket will be too deep.