Venom,
As others have said, it sounds like you're trying to use a Sentry document safe for your firearms. As you've discovered, this can cause problems due to the humidity from the moisture-content of the insulation material. You'll usually find plastic "plugs" on the walls inside the safe. These are intended to release steam as fire heats up the exterior and the moisture helps protect documents from the fire. Sealing these over with silicone sealant may reduce the ambient humidity inside the safe.
To help protect against the ambient moisture and condensation (usually caused by opening a cool, dry safe environment to warmer, moister household air), try using a
VCI product to help control the corrosion. Using a VCI barrier bag ("blue bag") might help, but only if you close it up outside the safe to prevent moisture from being trapped inside.
But you should really find a safe better suited for storing firearms.
Some Possible Solutions
I don't have your moisture problem, however I store my handguns inside silicone-impregnated
Bore Stores and add a
VCI card and keep a VCI emitter (shotgun shell sized) inside the safe. This seems to work the best.
Rust Removal
To remove light rust, rust spots and rust speckles, you should use a good penetrating oil, such as
Kano's Kroil. For light "brown" rust, soak an old rag in Kroil and wrap it around the gun for 10 minutes. Then use the rag to loosen the rust with a light rubbing action. You can "rinse" the gun with spray oil like Rem Oil or WD-40, then wipe down and relubricate the gun.
If rough rust spots form, use a
copper (not copper-colored stainless steel!) Chore-boy potscrubber pad with light pressure to remove the rust spot. The copper Chore-Boy will not hurt the bluing. A copper or brass brush
can be used but care must be taken to avoid too much pressure that could abrade the bluing.