Thick case necks can cause high chamber pressures and flyers. The Forster Neck Reamer mounts in the cutter of a Forster Case Trimmer in place of the pilot and removes the excess brass from the neck walls. Reamer is ground .0025" to .003" over the maximum bullet diameter. For use with the Forster Case Trimmer (sold separately). Notes: Use on unsized and untrimmed fired cases