I just got a lb of blackmz to try in my home built 50 cal muzzle loader...round ball gun. I typically shoot 65 gr of fffg, .495 round balls with lubed patches. The warning on the Black mz says to use no bullet/bore lube......
You should really like it with patched round balls. It LOVES heavy seating pressure, so remember that when you do shoot it. Lean into the ramrod and you'll feel and hear it crunch.