I've used a single Speer .457-inch ball in the .45-70 case over 10 grs. of Unique.
Seat the ball with its midpoint 1/16th inch below the mouth of the case, then rub some bullet lubricant in the space between the ball and case.
Makes a great, quiet plinking load in my Marlin 1895 with 22" barrel. Also good for little kids, who want to shoot a "real cowboy rifle." Accurate too.
I've also loaded three .457 inch balls over 10 grains of Unique. Place a .45-caliber wad between the first and second balls, then crimp the third ball at midpoint in the case neck.
Invert the cartridge and give it a quick dip, up to the neck, in Lee Liquid Alox for lubrication. Allow to dry before shooting.
I cut my .45-caliber wads from empty soda pop 12-pack cartons.
This is a fun load but it has a serious side. For a while, when I lived in Idaho, it was my house gun. I figured any intruder hit with three .45-caliber balls at about 900 fps wouldnt' survive to sue me.
But I gave it up in favor of a pump 20 gauge shotgun loaded with No. 3 buck.
The three-ball .45-70 load is a fun cartridge to let non-shooters try, unawares: One shot ... THREE holes! Another shot ... SIX holes!
Then you follow with, "What the heck are you doing?"
Usually, they're absolutely flabbergasted and can't explain why there are more holes in the target than shots.
About that time, I let them in on the prank. It's always good for a laugh and makes their first shooting experience memorable.
It's strictly a short-range load, no more than 25 yards. A big box makes a good target so the holes are plainly seen.