My Marlin 39A (my second) was bought in 1967, as I recall. I have a pre-WWII Stevens double 12 gauge. Both have been used in all kinds of weather. The only rust on either is a little on the outside of the shotgun, which was there when I bought the gun very well used, again in the sixties. Take care of carbon steel guns and you can pass them along to your great-grandchildren.
"Don't let macho be your epitaph."