I own and shoot an original 50 EX. 1886 and have had good experience with both 350 and 450 grain cast over IMR 4831 compressed using magnum LR primers.
Mine a 1/2 Octagon, 1/2 Magazine that came my way from the collection of a boarding house in Skagway AK.
It is a fun rifle, in part because of the history attached.
Years back, using the dimensions of the internals of this original I had another ‘86 converted and rebored to 50 EX. I wish I stilled owned that one as well.
Yes, you should find it a fun project. Bon appetite’
