Picked up three 12 gauge shotguns from my wife great aunt . Two Mossberg 500, one pre 1968 no serial numbered, 0ne 1973. One High Standard model 60. Remington 721 30/06. Great barrels on all guns very little wear on the insides. Wood in very good shape. Ben sitting in basement for nobody remembers how long. Didn't even know she had them. Problem is that all have heavy rust on outside, minor rust inside. I'm going to strip all down to bare metal and refinish, not reblue. Don't need them so going to grandkids when done. Will let the pick colors of coatings. Hopefully not pink. After all this typing my question is on the insides what do I treat with to prevent new rust on rails and tubes?