I have a blued single action that had substantial holster wear, some rust spots, and a few spots where someone tried to cold reblue it that looked even worse. After cleaning it with hot soapy water I used rust remover and a tooth brush, a couple times over, to remove the rust and all of the bluing with the intent of rebluing it myself. When I was done it looked so cool I kept it in that condition - stripped down to unfinished metal. It's now my daily carry chores around the property gun that I simply wipe down with gun oil about once a week to keep from rusting.
Back to your question....automotive rust remover and a tooth brush while the metal is warm works quite well to remove rust and bluing.
