Nearly 50 years ago, when I was first introduced to BP revolvers, Crisco (vegetable shortening)was a requisite part of loading and firing. It was messy to apply, messy to clean up after, but the wisdom of the day said that it made clean-up easier, since it kept fouling soft.
The disadvantage of petroleum products was their reaction with black powder residue to form even more of a mess than created with the veggie shortening.
Fast forward a few decades, and it was discovered that the chain-fire supposedly due to no lube over a seated ball in a chamber, was more mythical than factual, and that chainfires were more likely to occur via poorly fitted caps.
As for the need to lubricate a roundball -- lead is an excellent lubricating material, especially when balls in a revolver largely are propelled at a subsonic velocity.
Nevertheless, the desire for a little lubrication anyway, has a some of more viable and less messy options:
Grease pills - any number of recipes are available to produce a semi-solid wad inserted between powder and ball.
Felt Wads - Wonder Wads are available in the US that come precut and pre lubed. Many folks are on the eternal quest for sources of felt to make their own, and materials range from old felt hats, to window and insulating materials.
My personal favorite is to simply fold up a tiny dab of ball lube into a square ot toiletpaper and seat it over the powder, compressing it a little before actually seating the ball.
All of these methods serve several purposes:
For a light powder charge, a filler helps compress the powder charge, especially when the ball ram isn't long enough to fully seat a ball deep enough on its' own.
A greased pill, or wad provides a little lube that seems to keep excessive fouling to a minimum.
It is important with any wad formulation to keep the lube solid enough so that it won't squeeze out of the felt or paper and into the powder charge.
