The chalk method is best suited for cleaning unhardened metal.It's success on damascus or steel barrels is because the abrasive properties of the chalk are sufficient to remove surface rust without seriously impacting the origional damascus brown or barrel blue.
For restoraton of vintage guns with, case hardened,silver polished actions,I have used "Crocus" cloth,for restoring finish.This is cloth impregnated with a type of jewellers rouge. It can be purchased from most industrial supply or good hardware stores.
