When I bought the elderly NEF rimfire revolver, I noted it could have had better care. Not that it was abused or hard used, but it was beginning to spot with that most hated among firearm owners.... Rust.
It seems the cheaper the weapon, the easier they rust. Maybe that's just my impression.... but I seldom see such on a S&W.My go-to since a child, WD-40 and 4-0 steel wool were picked up to take care of this chore.
The grade of steel wool is critical. Anything courser, and you can kiss the metal finish goodbye. Even with 4-0, it's better to be light and gentle. Thinning the finish is easy, and any kind of elbow grease may remove it altogether.
Simply spray the steel wool pad with WD-40, and gently start chasing down any surface rust on the weapon. Frequently take a break from scrubbing and clean the surface with dry paper towels to judge progress.
This will remove surface rust without damaging the firearm, and leave a clean and polished looking finish behind. What it *won't* do is remove pitting. Anything that has penetrated the original finish... that's there for good.
For this old NEF revolver, it doesn't really improve the looks a lot, but it does make the rust cease it's evil operation. It also makes the pistol look like someone cares, and that means something. It's an ugly old survivor, like me.