buckstix,
A chamber cast is great, but a lot of times it isn't possible to discover what the maker of a rifle intended to call the cartridge it was chambered for. It doesn't make much difference anyway because you likely can't buy ammunition for it at the local "Mall Mart" or "Hook and Bullet" store. You will likely have to load it yourself or pay someone else to load it for you. This is because considering tolerances the dimensions of the two cartridges in consideration (one of which is unavailable and you have expressed reasonable hesitation to use modern loads for the other) overlap one another. Since you have cases and bullets that will fit or can be modified to fit, you can make useable cartridges and call them whatever name you like. It seems to me that you have another fun project on your hands. Whatever you come up with will be instructive to the rest of us. Enjoy.
Mike
