Forster Neck Reamer #284, For Original, Classic And Power Case Trimmers. Use With .284 Diameter Bullets., NR1284

224 .243 .264 .284 .308 .429 and many others. When reloading if the case neck is too thick it can put pressure on the chamber and cause flyers. By mounting this neck reamer in the Case Trimmer rather than the pilot it helps eliminate excess brass from the walls of the neck.