Thick necks can cause high chamber pressures and erratic shooting. Neck reamers remove excess neck material to insure adequate clearance exists between the case neck and the chamber. Also, these reamers can be used when forming wildcats from a parent case. Reamers are designed to be used in the LE Wilson Case Trimmers (sold separately) in place of the trimmer cutter. Standard reamers are sized for use on fired, unsized cases.