One expert on rare cartridges who may be able to help is Michael Reuter of http://www.sammlermunition.de/ You can write to him with a link to this thread, or, if you want, I would be happy to do this. He has been most helpful with information on some obscure rounds and he has a formidable collection of rare cartridges of his own.
Good hunting!
-------------------- The Ark was made by amateurs. Experts built the Titanic.