These L.E. Wilson Trimmer Case Holder (for fired cases only) are designed for pistol cases. These cases have practically no body taper and require a special type holder, which is constructed very much like a neck sizing die. Cases can't be "bumped" in and out of these holders like most rifle cases but must be forced in with a light arbor press or mallet and must be driven or pushed out. These holders are made longer than the cases to be trimmed so that cases may be forced clear in without damage to case mouth. Holders are counter-bored at mouth end for cutter clearance. Users will find the case trimmer somewhat slower on pistol cases than on rifle cases but it will produce a very uniform case length with consequent perfection in crimping. Designed to be used with FIRED brass. Sam (L.E.) Wilson, a champion pistol shooter believed trimming pistol cases first before resizing so you were not trimming your crimp away and aided in the seating process on pistol cases.