I believe the 71/84 mauser took 11.15x60R ammo.
buffalo arms has werndl 11.15X58R
Question is would that werndl round work in the 71/84?

and this is how i go astray.
have the rifle, no ammo.
https://www.youtube.com/watch?v=QjZiJ65rzgU

Buffalo Arms has 11.15x60R

i found 11.15x58R but not the 11.15x60R at buffalo arms.

I just "googled" 11.15x60R ammo for sale and Buffalo Arms came up. Expensive, but there.

When I was a kid, CIL made 43 (11mm) Mauser ammo in their Dominion Brand, but it was expensive even back then.

Search for "43 Mauser" rather than 11.15 x 60R.
That's how they were marketed in the US and Canada before WWII and that's still what most companies list and put the metric designation in parenthesis.
Graff's has the Bertram's cheapest.
I got Bell back 10 or more years ago. No problem with them, but they aren't made anymore.

good tip, that was the magic ring key code.
This rifle kind of awes me in a way. power wise, it resembles a 45/70, but made at a time when we were using single shot trapdoors, they stuck an eight round mag on it.
it was made in 1888 spandau, and all numbered and cartouched, bluing is excellent on barrel.
I don't think it was shot much if at all.

i ended up getting it at buffalo arms, 5bucks a round loaded but oh well.
Gonna be interesting.

Keep us posted on your progress.

i got the buffalo ammo in, and it cycles just fine in the rifle.
now comes having to take it out somewhere and burn a few, with some pictures. I have a 1855springfield at the same state
and a couple of english .577snyder rifles to figure out out to get some brass or loaded ammo too.
one of the 1800rd's enfield has to be fired too. It came back from the stans.