hoppdoc:
Chasseur's advice is sterling for the exterior, but I would go further and strip the locks, polishing any rough surfaces (being careful not to touch any tolerance-critical surfaces), then coat everything with a thin film of water-proof corrosion-inhibitor, and re-assemble. I do this as a matter of course with any new acquisition, doubles included, as it is not uncommon when hunting here in Australia's monsoon tropics to get caught out in an absolute drencher of a storm, and the heat and humidity are extremely unforgiving.

I make my own concoction, a 50:50 mixture of uncolored waterproof grease and high-grade light machine oil. I use Al-Com No.2 grease made by Molybond, and german light machine oil or Singer sewing-machine oil. It takes a bit of shaking to get them to mix, but the resultant 'honey' sticks like the proverbial, won't dry out, and resists wash-off more than any commercially-available product in my experience. It is the perfect lube, too. I do DG internals and bolt-gun barrels (in the barrel-channel) about every other year, never had a single speck of rust.

This stuff is excellent for wiping down the collection pieces prior to our monthly display meetings, where valuable arms are handled by dozens of enthusiasts all night! Should take the Alaskan wilderness in its stride!

Also, a parting thought. The relatively new lanolin products should be pretty good for external metal-work protection too, they reportedly coat ship's propellors to prevent fouling! Not sure what is available in the States, but here we have Lanocote (UK), Lanoguard (NZ), and Lanotec (Aust), grease-tub or spray-can.

Hope this helps.