At the SCI show, Gunmaker Philipp Oliendorff had a fine break action single shot rifle on display in this chambering and I've seen it referenced by other European Gunmakers a few times since. Does anyone have any historical data or ballistic information for this cartridge? Is this an original case or is it necked down from 9.3x74 or something else?

Thanks in advance
Oh, here's a picture of the Oliendorff 7x75R