Raimey,
I'm over my head when you start asking about a Gebrauchsmuster.
However, thanks for posting the reference to the earlier thread which pictures pages from the Sempert & Krieghoff catalog. One such page illustrates both the "herausnehmbares Schloßgewerk" and the "automatische Kugelschloßverriegelung" perfectly.
I had the impression that the "Schweinsrücken", so pronounced in the stock design of the drilling I just bought, was a post war development. I have four pre-war drillings, a Sempert & Krieghoff Neptun, a J.P. Sauer & Sohn Model 26, and two Greifelt drillings, none of which has a hint of a "Schweinsrücken", and I saw no mention of such a stock design in the Sempert & Krieghoff catalog. My post-war Neptun did, however, have such a feature, until I had it removed.
My 1939 Marholdt Waffen-Lexikon refers to "Schweinsrücken" in connection with telescopic sights, so that might be a possible explanation, although two of my pre-war drillings have scopes and straight combs.
