How to Remove Crimps From Primer Pockets on Military Brass

Ammunition reloading hobbyists prize once-fired military brass cartridges because they are high-quality components, and are relatively inexpensive compared to commercial brass cases. Unlike commercial cartridges, however, the primers in military cartridges are crimped into the primer pocket, so they can better withstand rigorous handling in the field. The crimp has to be removed before a new primer can be pressed into the cartridge as part of the reloading process. Reloading tool manufacturers make a variety of pricey specialty tools for removing the crimp in military brass, but you can also use a common reloader's chamfer tool to achieve the same results.

Things You'll Need

  • Chamfer/deburring tool
  • Primer pocket cleaning tool
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Instructions

    • 1

      Examine de-primed cartridge cases to determine which type of primer crimp they have. A ring crimp appears as a small ring stamped around the circumference of the primer pocket. These are typically found on U.S. military surplus brass and require less reaming. Stab crimps look like short metal tabs folded into the side of the primer pocket, and require more reaming to get a uniform result.

    • 2

      Pick up a cartridge case in one hand and your chamfer tool in the other. A chamfer tool has carbide cutting blades on both ends. On one end, they face inward toward a small metal post; this end is used to deburr the outer rim of a case mouth. On the other end, the cutters face outward and come to a point; this end is used to bevel, or "chamfer," the inside rim of a case mouth. The pointed end of the tool is also used to ream primer pockets.

    • 3

      Insert the pointed end of the chamfer tool into the primer pocket. Hold the tool at a 90-degree angle to the case head (the bottom of the cartridge). Press the tool against the case head with a firm, medium pressure and twist it back and forth two or three times to remove a small amount of brass from the mouth of the primer pocket.

    • 4

      Check the primer pocket. If the primer pocket doesn't have a clean, square edge, re-insert your chamfer tool and give it one or two more turns. Reaming trims away the narrow, flat notch of ring-crimped pockets, and removes all traces of the brass "tabs" created by stab crimping.

    • 5

      Set aside the chamfer tool. Blow out any metal dust that may be inside the primer pocket. Insert a primer pocket cleaning tool into the primer pocket. Twist the tool back and forth in the pocket a few times to remove any remaining residue.