I know that some chemicals in some foam can strip bluing just like some propellants in spray oils and penetrating oil (the propellant is desolved in the oil) I keep my 45 in a soft pistol case but every so often I it gets a quick once over with a oily rag
Can you still get wax or oil paper, the stuff that percision tools used to be wrapped in, if your storing your guns a once over with a vapour release oil (the stuff that releases a vapour that prevents corrosion even on metal you missed with the oil) then wrap in the oil/wax paper should prevent any corrosion.