Forster Outside Neck Turner Accessory For An Original Case Trimmer. Why is that important? Here's what The American Rifleman says: "Case necks thicken from repeated firing. This condition may prevent the neck from expanding properly to release your bullet. This lack of neck clearance leads to inaccuracy and has even blown up some fine rifles over the years." Unlike hand held neck turners which are centered only on the pilot the Forster Outside Neck Turner turns your case neck concentric to its true axis. It produces neck walls of uniform thickness and exact outside neck diameter. Properly adjusted it will turn necks to within a tolerance of .0001". The cutter head of the Outside Neck Turner has an adjustable circular carbide cutter for a lifetime of reliable use. In operation the wall of the neck passes progressively between the pilot and the cutter as the neck wall of the case is reduced to a uniform thickness. You control the rate of feed by rotating the feeder cam while a mechanical stop controls the length of the cut. The short pilot used in case trimming is replaced with a longer hardened and ground pilot of the desired caliber. To change calibers (any diameter from .224 to .375) simply insert the correct pilot and make the necessary adjustments. NOTE: The Forster Outside Neck Turner is designed to be used after the neck has been resized and expanded. Cases longer than .375 Magnum (2.94") require a long case trimmer base. Specifications for Forster Outside Neck Turner: Manufacturer: Forster Quantity: 1 Package Contents: Forster Outside Neck Turner Forster OT1010: Outside Neck Turner Accessory For An Original Case Trimmer