Metallic cases stretch as a result of both the firing process and the subsequent resizing process. When your cases reach a certain dimension, the original case length must be restored through trimming. The Lyman Universal Case Trimmer features the patented Lyman Universal Chuckhead which allows the reloader to quickly lock and unlock a cartridge case and handles any case from .17 caliber to the 458 Winchester Magnum without the need for costly collets. Other features of the Lyman Universal Trimmer include an adjustment ring that allows you to dial in the approximate trimmer setting for ease of repeatability, fine and course length adjustments.