A trimming, sizing and decapping device that has a simple, very compact construction and that allows the user to economically and quickly produce, restore or prepare cartridge cases to the utmost precision. The device consistently produces very smooth processing surfaces and has good tolerances with respect to various cartridge case wall sizes and materials. Furthermore, a method is detailed for producing or preparing empty cartridge cases using the trimming, sizing and decapping device that allows efficient preparation of the cartridge cases for subsequent loading or reloading in as few process steps as possible.