Please get some light machine oil like 3-in-1 sewing machine oil, or visit a gunshop and get some gun oil. Put a very thin coating on the metal to prevent any further corrosion. Get an inexpensive rifle cleaning rod and cut a patch of old cotton T-shirt that will fit in the rifle bores without getting stuck. Saturate the patch with oil and run the patch back and forth a few times in the bores to coat them with oil to help prevent any further corrosion. Don't get any oil on the wood.