Gun maintenance includes removing rust that has set in during storage or lack of regular lubrication. The main concern of rust removal is to retain the gun's bluing. Regular oiling of the gun will prevent rust from setting in, but once established, rust must be removed with care and patience. The materials needed to safely remove rust are readily available and the procedure is straight-forward.
Unload the gun. Remove the magazine if it has one and check the chamber to ensure that it is empty.
Cover your work area with old newspapers. You will be using oil to work on your gun and it will go everywhere. Have rags handy for cleaning up.
Swab the rusted area on your gun with gun oil. In a pinch, regular household oil or even vegetable oil will work. Rub the area with a cloth and remove as much rust as possible. Continue to swab the area with oil and rub it with the cloth until no additional rust can be removed.
Apply more oil and rub it with number 0000 steel wool to remove any remaining rust. Do this carefully to prevent rubbing off the gun's bluing.
Wipe the oil off the treated area to remove any rust particles that were trapped. If rust remains on the gun, reapply oil and continue to rub the area with the steel wool. Repeat the process until the rust is gone. Finish the process by lubricating the entire gun.
Use a wire wheel carefully to grind out any areas of deep rust that can't be removed with steel wool. This procedure will remove the gun's bluing, which you must replace immediately to protect the metal. Finish the process by lubricating the entire gun.