Score! A bud's 58 MR launched our whole bunch onto the search path, and I can tell you we all had to settle for substitutes. Fine rifle, and they're hard to come by.
Dunno what your rifle will settle on, but his is a one-holer with 100 grains of any 2f (Goex or Pyrodex RS, it doesn't care), with .570 balls and ticking patches lubed with any grease lube.
And that load just smacks the snot out of deer to all reasonable ranges. He's whacked one elk with it at 75 yards. Same result.