therein through a die and passing the cartridge case with the punch member completely inserted therein through the die moving from the base to the top of the cartridge whereby the new inner and outer dimensions are obtained e g see fig8 the new inner and outer dimensions diameters may be smaller than the original inner and outer diameters of the propellant chamber portion of the original preexisting cartridge case the passing step may increase the overall length of the cartridge case and the method may further comprises a step of after the passing step trimming the cartridge case to a preselected overall length by removing a top portion thereof for example by cutting or grinding off a top portion of the cartridge case e g see fig9 following the foreshortening of the cartridge case if desired the cartridge case may be formed into a bottleneck case configuration for example using conventional methods the method may also include a step for converting a berdan type cartridge case having an integral anvil that protrudes from the top of the primer pocket downward for use with berdan compatible primers e g see fig4 to a boxer type cartridge case having a central flash hole for receiving a boxer type primer having a primer integrated anvil e g see fig6 thus when the preexisting cartridge case is a berdan primer configured cartridge case the method may further include a step.