Use Soap and warm water to clean these guns- NEVER an oil. Then get Sheath, or some other similar product made by Birchwood Casey. for long term storage. Oil the action( lock) parts with a good vegetable oil ( olive oil works fine, but is expensive), and wax the stock, both inside the mortise, and outside to protect the finish. Put the guns in plastic bags sealed, to keep out moisture. You can buy dessicant bags at many of the hobby stores, and they can be placed inside the plastic bags to suck up any moisture in the bag. Put the guns a cool, DRY, place while you are gone. Covered in plastic bags, and well oiled, you should not have any problems with rust while you are gone. If you are near the Ocean, salt laden air is a problem for storing anything metal, so don't skimp on the oils and wax.
I have a friend who put lots of guns in a wooden case years ago for storage, to keep them away from his growing children. He forgot about the guns until a few years ago. He had oiled all the guns, and then wrapped them in thick heavy waxed butcher paper( Check office supply stores to see if you can order this). This is the same kind of paper that many commercial guns were wrapped in before plastic bags in foam lined, plastic cases became the "rage". All the guns, stored more than 25 years, were in perfect condition when he pulled them out of his attic. He feared the worst, simply because an Attic is about the worst place to store anything. Its too hot( except in the winter time), and its too moist. However, he came through okay. Many of the guns were from a museum that closed down in Upstate New York, and the guns were still in museum quality condition. He has since loaned some of them to the National Firearms Museum operated by the NRA at its office building in Fairfax, Va.
