6.5mm BergmannThe 6.5mm Bergmann is an unusual centerfire cartridge produced for the 1896 Bergman #3 self-loading pocket pistol.DesignThe case is bottle-necked and steeply conical, and headspaces on the conical case walls. Early versions were made without any rim or extraction groove; and relied upon blow-back for expulsion of the fired case from the chamber. Later Bergmann pistols provided an extractor requiring a groove which produced a semi-rimmed case.