my previous title should have been 9.15 x 48 norm

[proudhon]

sorry for the mixup
joe

[Diz]

Joe,

I searched my references and couldn't find such a cartridge. There is a 9.1x40R and a 9.3x48R and I even have data for a 9x47R Deutsche Schutzen which I have an idea it might be. The 9.3x48R can be made from 9.3x72R and 303 British I believe. I am not sure about the others right now and will take more study. Others on this board are much better informed than I am. Best of luck.

Diz

[mike ford]

Joe,
The proof marks on these old rifles are not the nominal caliber. Rather, they show the bore(not groove or bullet) diameter and longest case the chamber will accept. Often these numbers differ from the nominal caliber, and are seldom marked with it either. It is likely that the rifle is chambered for a target cartridge, rather than one intended for hunting. According to Dixon, there was a 9.15x47RV, AKA 9.15x47b. This cartridge has a very unusually large head diameter of 14.4mm, which in my mind would exclude it. On the other hand a chamber with a diameter large enough would positively ID it as that caliber. Cartridges usually( not always)had bullet diameter larger than bore diameter. A 9.15mm bore could use a 9.3mm bullet. There is a 9.3x48R Express, as mentioned by Diz, which is based on the English 360 base, as is the 9.3x72R. This cartridge, however, was intended for hunting, and would seldom be found in an Aydt. There is another possibility, the 9.3x47R MB Target, AKA 9.3x47R Springer. This cartridge was based on the 11.15x60R Mauser case, which has yet a different head size known as Mauser Base( ie MB). The Aydt was most often found chambered for 360 based cartridges, but the 9.3x47R MB was available until 1914, which would be a couple years into the time bore diameter in mm and case length was used in proof marks. What this boils down to is, with the info given, we just can't ID the cartridge your rifle is chambered for. You should make, or have someone else make a chamber cast, and "slug" the barrel. With precision measurement of these, I think we can ultimately help you.
Mike