From LOTS of personal experience from upwards of 80 firearms in saltwater conditions I may be able to help on this one. In the Navy we use Break Free CLP. Its not just a solvent, its a cleaner, lubricant, and preservative. I would first try a bit of clp, let it sit for a few and just brush the rust off with a soft tooth brush, possibly even just wipe it off with a soft rag. 0000 steel wool is fine, but I tend to use it quite sparingly. Eventually the steel wool will break down the bluing and create more problems. Try the CLP, you will be impressed. Just apply generously, let it sit, then wipe off any excess. I use it on all my personal firearms now, and use them at upwards of -20 to 110 F without any real problems.
Good luck
