Deleted member 118572
only on outside.
I put in a ultrasoundPersonally, I'd try a bit of PB Blaster (good ol' panther pee) or some other penetrating oil first. You don't need a lot. Let it it soak into the rust for 15 to 30 minutes and then hit it with a worn out bronze bore brush or a mild wire brush. Why risk the pins marking up the inside of the die for what is really just a cosmetic defect (assuming the rust is only on the outside knurling).