Well, when I was looking over information on black-powder cartridge loading I ran across an article(here, it's a pdf) that had a number of make-it-yourself lube recipes. Short version is that in cartridges loaded with black, the lube both has to lubricate the bullet as it goes down the barrel, it also helps keep the powder fouling soft. Softer, at least. And such lubes tend to work well with cast bullets and smokeless propellant as well. So I decided to try one, directions from the linked article:
(1) Melt 4oz by weight bees wax in a Pyrex dish in your microwave on high 12 minutes orSo far we've only used it with smokeless loads. Procedure has been to put on gloves, take a bullet swipe up some lube and wipe it into the grooves, then push the bullet through the sizing die(Lee). So far it's worked beautifully; no trace of lead fouling in the bore. So I'm going to try it on some other cartridges and see how it works out. If it's good, well, I found directions for how to make your own lube sticks...
(2) Add 2oz of pure Neatsfoot oil by volume (use one of those little plastic measuring
cups). Pure Neatsfoot oil can be found in most well-stocked Tac shops.
(2) Add in 2oz of Murphy’s oil Soap, pour slowly, and be careful! When you’re adding
the soap it has a tendency to boil over. The soap causes spontification, which raises the
melting temperature of the lube. Stir the mix until all the lumps are gone. Then either
pour it into a suitable container or directly into your lubesizer.