My Mossberg truck gun rusting

[Koolmoose]

There are a couple of ways to easily prevent rusting on a vehicle gun.

One is to apply a medium-heavy coat of Johnson's Paste Wax and let it dry 30 minutes, then without wiping it off, store the gun.
This is a trick used by saltwater duck hunters to keep their guns from corroding.
Many of them apply the coat of wax then warm the metal with a hairdryer to melt it. This gives a uniform coating that cools to seal the metal.
Note that car wax is NOT suitable for this use.
You can buy big yellow cans of Johnson's in most hardware stores and many Walmart's.
It's also a perfect treatment for gun leather.

A second great treatment is to use Boeshield T-9.
This is a rust preventer developed by Boeing Aircraft to prevent corrosion inside sealed wings and other areas that can't be inspected later.
This is a wax base that's sprayed on in a liberal coat, and then drys leaving a wax coating that seals the metal.
This widely used and recommended to prevent rust in many industries.
Buy online.

+1 on the BoeShield. I first heard about it on a tool forum as a fix to prevent rusty tools. It has kept all my blued finished gun from any rust. I live on Cape Cod where the weather can be quite humid. Vehicles parked outside are often coated with moisture (like a lot of places I suppose), but when that moisture dries the vehicle is covered with salt streaks. It doesn't help that the village I live in has salt water on 3 sides.

Last year I bought a Henry Big Boy in 357 Mag with a blued finish. When I brought it home I coated it with the BoeShield, but missed a tiny spot under the lever. When I took the gun out of the safe a few days later everything was shiny new except for that tiny rust spot.