cable,
If you sell it before IDing the cartridge, you would always wonder what it is. I think the bore diameter is a little small for a nominal 11mm, maybe something like 10.75 or 10.8. Did the rim of a 45-70 case fit the extractor? If it did, it is not a Mauser Base (MB) case. When I make MB cases from 45-70; in addition to moving it forward, I have to reduce the rim diameter from about .608" to about .595"( the book says .585"). It would be a shame to let it go, you seem to have an interest in old German guns. If you are not already a member, I think you would enjoy being in the "German Gun Collectors Assn."
Mike

Last edited by Der Ami; 04/15/20 07:37 PM.