What a beautiful rifle! I'm in somewhat of the same boat, getting materials together for what-I-assume is a 43 Mauser rifle. I need to cast the chamber and slug the bore, but the prior owner "pinky swears" it's a 43 Mauser.
If you search "43 Mauser" on the Buffalo Arms website, you'll see dies, brass and loaded rounds. They are often out of stock, but I kept looking and bought Redding dies, RCBS #22 shell holder, some Bertram brass and bullets. This was two years ago and sadly haven't done anything yet but hope to this winter - just like last winter....
The shell holder was recommended due to the odd case head of the cartridge, which is thin towards the edge as Der Ami stated above.
A few Double Gun Journals (START THE MAGAZINE AGAIN please!!!!) have nitro-for-black load suggestions for the 43 Mauser and other black powder cartridges. I will endeavor to find those and list them here. The loads suggest a dacron filler. I purchased a bag of that from Michael's craft store.
Hope to find the articles and post the suggested nitro-for-black loads, may take a bit.
Good luck with that beautiful rifle!
