375whelenIMP,
The 9x36R Tesching , shown as T17 in Dixon's European Sporting Cartridges was included with the "T" type Tesching cartridges, inspite of not having an "A Base", because the head and rim diameters are the same. This matches your memory of the chamber cast, and would be the type cartridge typical for a small Martini. Dixon shows the bullet as only 8.99mm diameter but black powder rifles often used a bullet smaller than groove diameter, counting on the soft lead bullets to "slug up" ahead of the black powder, sealing the barrel. Dixon shows it in use from 1880-1910, which roughly matches the rifle. I still believe you can make cases from 303 Savage cases( see Graf & Son) but since they would have to be significantly shortened, the necks would likely need reaming or turning.
Mike
