One thing is certain... prior to Edwin Drake drilling the first oil well, black powder lubricants were not petroleum products. And it has been shown that the older plant and animal fat based lubes were less corrosive when used with black powder.
When I started shooting flintlock and percussion guns, I had after-rusting in my bores no matter how carefully I cleaned, dried, and oiled them. Then I switched to Thompson Center Natural Lube. I now clean with hot water only, and swab the bores with the same T/C Natural Lube after drying thoroughly. I no longer have any issues with after-rusting. The principle involved is the same as the process of "seasoning" a cast iron skillet.
Knowing what I know now, I don't ever want a drop of petroleum based lube or cleaner anywhere near the bores of my black powder guns.
