Rust on guns is like death and taxes— an unpleasantness that affects us all. To remove an unwanted bloom of rust on a gun, dab some gun oil on the afflicted area and work it over with a piece of No. 0000 steel wool. This extra-fine grade of steel wool won’t scratch or mar the metal on even fine guns. Once you've removed the rust, wipe the metal with a cloth to remove any small bits of the steel wool that may have come loose, and then apply a drop or two of gun oil for protection against future corrosion.