There are all kinds of videos on Youtube and other places showing people vacuum sealing all kinds of things. I have even seen them vacuum sealing firearms.

I actually think for longer term storage of rarely used firearms that vacuum sealing may well make a lot of sense, despite how it may sound at first glance.

I know some coin collectors seal up coins to keep them from tarnishing. Even slabbed coins are not air tight and can tarnish over long periods of time.