How to Trim Rifle Cases

Every rifle case must be checked for size before reloading. Rifle cases stretch when they are fired, and they stretch again during the sizing process. During the reloading process, the cases are trimmed to remove this extra length. If a rifle case is loaded without being trimmed, the resulting cartridge may not chamber correctly. A cartridge made from an untrimmed rifle case may also result in unsafe, dangerous chamber pressure when the cartridge is fired.

Things You'll Need

  • Sized rifle cases
  • Dial calipers or case length gauge
  • Reloading manual
  • Case trimmer, with appropriate caliber pilot
  • De-burring tool
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Instructions

    • 1

      Set the dial calipers or case length gauge to the trim-to-length specified in the data section of the reloading manual. Be sure to use only the length referenced for the caliber you are reloading.

    • 2

      Sort the rifle cases by placing each case in the caliper or case length gauge opening. If a case will not fit in the opening, set it aside to be trimmed.

    • 3

      Insert the correct caliber pilot into the cutter head of the case trimmer and tighten the pilot lock screw.

    • 4

      Open the chuck lever and insert the head of the rifle case into the chuck head. Rotate the chuck head until it locks, but do not engage the cutting head bar's lock collar.

    • 5

      Push the cutter shaft so the pilot enters the case opening. Make sure the cutter is in contact with the case opening.

    • 6

      Turn the chuck lever until it is in the locked position.

    • 7

      Turn the handle of the case trimmer until a small amount of brass is removed from the end of the case.

    • 8

      Remove the rifle case from the trimmer and check its length. If it is still too long, repeat the cutting process until it is the right length.

    • 9

      Lock the collar on the cutting head bar once the case has been trimmed to the correct length. All of the cases can now be trimmed to the proper length.

    • 10

      Check a rifle case periodically to make sure the collar has not slipped. If it has slipped, trim a case until it is the correct length, and then lock the collar again.

    • 11

      Deburr the cases after trimming by running the deburring tool on the inside and outside of each case.