The 8mm Bergman-Simplex cartridge, also known as 8mm Bergmann Nº 6 and 8x18mm Simplex,[1] is a centerfire smokeless-powder rimless straight sided cartridge developed by Theodor Bergmann for his Simplex pistols.
Original loadings of this cartridge fired a 71 grain bullet at 790 feet per second.
[2][3] This is an notable cartridge because Bergmann has previously experimented with tapered bottleneck designs that had no extractor groove, as well as similar designs with an extractor groove, and this design settles on a straight side rimless design, a form most semi-automatic ammunition will take.
Furthermore, 8x18 Simplex is designed with sufficient power to operate the recoil of the weapon, but to also avoid the necessity of a locked breach, simplifying construction.
The impact of this cartridge, like the more successful 7.65mm (.32 ACP) cartridge, provide a pathway to an entire class of pocket pistols that are simpler to design and manufacture, and less lethal, than the heavier energy deliveries of the locked-breach, more military style firearms.