When I had a .45-70, I used a commercial (Speer) .457" lead RB over an Ox-Yoke lubed wad & 35gr Goex FFFg as a plinking load w/o issue (except for cleaning).
There was an entire article, covering these gallery loads, in an issue of Guns Of The Old West a few years ago.
I notched the rims of the brass used for the BP gallery loads, so they wouldn't be used for anything else, though.
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