Once it is pitted it is permanant, unless you plan to sand it down and refinish the entire gun. Brownells makes a very good cold blue that a lot of gunsmiths use and it is easy to apply but will not cure the pitting. a dremel with a small stainless steel brush will get the pits cleaned of all rust or you can use OOO steel wool. When all clean then use OOOO before refinishing and a cold water rince and buff with the OOOO before the next coat. Usually 3 coats works good.
CPL holder since 1991, NRA Lifetime Member, DU Member, NICET certified
"For those who would give up essential liberty to purchase a little temporary safety, deserve neither Liberty nor safety.—Ben Franklin.”