Not too hard at all. Just purchase some Hornady .457 Round balls to put into the case mouth. I personally use no wads or fluff with 10 gr. Unique in my .45-70 Buffalo Classic with a 32" barrel. Since yours is a 22" barrel, I'd start at 6 gr. and work up. Just make sure each shot you try fires correctly and doesn't stick in the bore by running a cleaning rod through the barrel if you aren't positive it exited. I have mine accurate enough to hit a groundhog at 100 yards, did so once anyway, but the POI (point of impact) is about 4" right of where I aim, so I kentucky windage it.
Don't go too fast with em though, because they will strip and lead your barrel fiercely over 900 fps. I use fireformed brass and keep it separate from my others. I never full length resize these as it will make very unaccurate ammo pushing the ball in as it will shave off or smush the diameter some. I do use my Lee Die sets case mouth expander die for .45-70 to seat the balls to a consistent depth, right at the hemisphere of the ball. Actually, about 30 thousandths past 1/2 way. Then my last step is to kiss it, and I mean really lightly, with my Lee FCD die. If you overcrimp this, you will have inaccurate ammo also with these. They are about like a light .45 ACP shot for energy, so the roundball isn't too powerful by 100 yards. Energy is down to about 164 foot pounds at that range, so you can see it's definitely not for hunting larger critters. It did smack down that ground hog though.
One last word of advice, I find that these round balls tend to ricochet a little more easily than flat point bullets, so keep it in mind until you play with them some.
