Quote:
he 9mm Parabellum cartridge case and its chamber ordinarily have a slight continuous straight taper. However, some chambers have been machined to have a straight, parallel-walled section, as visible in the photo. Its purpose is to extend the time during which the chamber is obturated as the cartridge case is extracted. (The seal formed by a taper breaks almost instantly.) Georg Luger patented the idea in 1911, and it was used on practically all Luger pistols made by DWM and Mauser through WWII, as well as on some German submachine guns
Quote:
An email to Smith and Wesson, including an attached photographs of the chamber step and brass "necking" produced the following response from Mark Rossini:
"Sir –the gun uses a stepped chamber"
This seems to indicate that at a minimum, some PPSs use a stepped chamber, but doesn't indicate whether Walther recently made a switch from tapered to stepped chambers in the PPS line, or why some individuals (Surreal) would have PPSs without the step.
I have a customer service email outstanding with Walther Customer Support as well. I'll post here if anything interesting or informative comes of it.