If you go round ball, I would start with a .530 ball and a .015 patch. Almost every 1-48 barrel I have messed with likes that combo to some degree. Try a .535 ball later if it doesnt like the 530's. Conicals will be hit or miss so to speak, some 48's like them, some dont. The Great Plains would be a good place to start.
Clean with soapy water. Dont forget to pull the lock and clean it as well. BP residue gets in there and makes a friggen rust pot quick if neglected. Give the cap recess in the hammer a good cleaning too. I usually dry the barrel with a few patches, pour a bunch of rubbing alcohol(>90%) down the bore, then oil it up. Put some anti-seize of some kind on the nipple threads before you put it in.
