During a visit with a dealer buddy last evening, he pulled out a German hammer double rifle chambered for what he described as a Sauer proprietary cartridge of 9.3x58R. It's a lovely, relatively lightweight little piece, with minimal engraving and fairly plain wood, but in wonderful condition for its age (proofed in 1914 according to the markings) and I'm interested in it. I've been unable to locate any information regarding the cartridge. All Mike could tell me was that he thought the cartridge could be formed from 9.3x72R.

So, is this a cartridge any of you out there are familiar with?