JB, you better go check you SKB right now!! Just discussing using Pyrodex with any mentioned firearms will cause corrosion!
Before I dabble with BP Subs, I did alot of reading about Pyrodex, and nothing good. I have seen photos of ruined Rugers that used Pyrodex.
And how fouling finds it's way into the action of shotguns, or any firearm, I can only say to stay away.
You can ask Smilin' Pete how Pyrodex ruined the actions on his firearms, and how he had to get them rebuilt.