Brasso works well on rust, after a wipe down with a cloth soaked in Coke, followed by a rinse with a wet cloth. you could use phosphoric acid instead of the coke, but typically coke is easier to get, and the only time I buy it is for cleaning stuff, as it makes a fairly good grease remover for clothes. If you want them to stay shiny use car paste wax on them after the Brasso is wipes off, cleaning first with alcohol to get the film of oil the Brasso leaves. Wash hands thoroughly after this, if you get any of the Brasso into your mouth or nose you will feel like the world is falling out your bottom.
As apprentice one of our instructors was a shooter, so we would be tasked with cleaning his pistol every week. Polished the whole pistol after stripping it to components, oiled them up, put it together and polished the entire box of 9mm ammunition it had, so it was spotless and gleamed.