Walt
ANY EXCUSE TO BUY A NEW GUN is a good one! Those Rugers will take to black powder like a duck to water. If memory serves you'd be shooting those "38-20's"? I have a pair of vaqueros in 357, and I guess if I were a true competitor, those are the ones I'd use. Lots of bang, plenty of smoke, and little recoil.
In small cartridge my preference is FFF, but I like all the BANG I can get for my buck, FF will work just fine, actually a little less recoil if your really paying attention.
Actually loading black powder cartridge is pretty simple:
Measure the depth of the cartridge case, the one I just happen to have right here in front of me is appx. 1 1/8"
Next measure from the base of the bullet to the crimp ring, if it has one, where your going to crimp if it doesen't. The 158gr RNFP heat just happens to be here too is 3/8"
Subtract bullet from case and you have case volume= 6/8 or 3/4" in the case for powder. We want a little bit of compression for black powder, so we are going to add an extra 1/8" of powder for a grand total of 7/8" of powder resting in the case.
Here, we're gonna make a powder measure, file off 1/4" of a 357 case, wrap a piece of picture frame hanging wire around the base, twist, wrap around again near the top. Ya now have a powder dipper that'll toss an near perfect load ya can adjust later on your own while your trying to get'em to shoot into one hole.
Pour in the dipper level full of powder and seat the bullet. You now have a good shootable starting point for those "38-20" Rugers