Any good quality oil will prevent rust. Slip 2000, Frog Lube, Rem Oil, etc., all work when applied lightly. You could degrease the metal with alcohol then apply a layer of polish. Flitz has several kinds of polish for different purposed and is my presonal favorite. Something like Mother's Car Polish will work too. This gives you a protective base layer.
The problem with 742's and their kin that gives them the nickname "Jam Masters" is not being able to easily and properly clean the chamber. There is a special brush made just for this task. I mention this because your extractor issue might indicate you have a gummy/rusty chamber. That's the number on cause of 742 extraction and feeding issues. If you're handy take the barrel off and check. If not, go see a gunsmith.