The Forster Case Trimmer Pilot is an inexpensive item used for home reloading and made for Original, Classic, and Power Forster Cast Trimmers, including all of the popular calibers. When choosing the correct trimmer pilot, it is imperative to purchase the right diameter. This is the inside of the neck diameter after full-length sizing of brass. The diameter of the trimmer pilot needed will be just slightly less than the actual diameter of the bullet. For assistance in choosing the appropriate size trimmer pilot, information is provided on the Forster website.