I would say BKF and the ScotchBrite will do it if anything will. Obviously not a SS corny if it is actually rust though.
"I brew with a water cooler and some part from the toilet." - JohnnyO
"I do gravity feed the last gallon or two through my Therminator, but I expect you could suck start a Volkswagen before you could suck start one of these. - GilaMinumBeer
"..... Bull was right." - TXCurtis