Randy, you just might have me switching over to the Breakfree I use on my other guns. However, I have to say that there's never been a speck of rust on my Black Diamond, and all I've used is bore butter, applied thinly with a patch when the metal is still hot from hot water that's evaporated. Anything greasy will keep air/moisture away from metal, as long as that metal's clean and dry to start. That experiment to which you gave a link purposely did not clean the metal very well; those lubricants effectively sealed corrosive residue into the metal; why they all didn't rust, I can't explain.
Whitfang, my Black Diamond likes to shoot 240 grain Hornady XTP .44 cal bullets in TC Mag sabots, pushed by two 50 grain pyrodex pellets. I haven't experimented with much else, because that combination has worked very well. Something like 3" groups at 100 yards (not sure because I haven't measured), which is fine for the 50 yard or less range at which I hunt deer. Killed my first ML deer with it last season: the same six-pointer that had walked straight to my tree, stood straight under my stand, then walked straight away from my stand the day before - couldn't kill him 'cuz I had a bow in my hand that day, and he didn't give me the angle!