I have one I been shooting since 1996, a 36" Colerain 75 cal swamped.
Have tried more than a few combinations over the years.
Always worked best with 75Gr 2F. Moose milk for trail walks and any kind of grease lub for hunting. Used .530 balls and .018 patches, now using .535 balls same patch and load.
It is a tack driving deer killer. Killed one once near 200 yds, plenty at 50 to 80 yds.
Truth is I have killed more with it than all my other guns combined, including a 270 Winchester.
As my Sons started hunting I let them use the 270 and I took a black powder gun, usually this 54 cal.