The 5mm Bergmann is an unusual centerfire cartridge produced for the 1896 Bergman #2 self-loading pocket pistol. The case is steeply conical and headspaces on the conical case walls. Early versions (sometimes called the 5 mm Bergmann Rimless) 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. The long bullet was inadequately stabilized and tended to tumble in flight.^[1]