I reload for my M1886 and the only brass that is available (I think) is Bertram. The Krop brass has quite a pronounced chamfer on the rim and is a totally different beast to the 8x60S case. I have formed some from 348 Win but it needs to be chamfered and by the time you have got it just right there is very little meat left on the rim which makes it easy to rip the rim off when sizing.
There was quite a bit of surplus ammo about a few years back but it was mostly wooden tipped blanks/training rounds and the cases would more often than not split on firing, so back to square one!
When you get to the point of getting the components for shooting the old girl, slug the bore carefully as the bores vary-mine slugs out to 8.04mm bore and 8.407mm on the grooves (a hardly used, mirror bore) whilst others will quite happily shoot a 0.329" bullet from a common Lee mould. I resize a 0.340" gas check boolit from a NOE mould and it works great with about 11 grains of Unique.
Lovely rifles to shoot, surprisingly accurate and a buttery smooth action, hope you enjoy it.