I don't understand the fascination with stainless, or plated guns, when we are talking rain/snow.
I have hunted the last 2 deer seasons with a blued Maverick 88 or Mossberg 930, and almost everyday was wet as can be. Constant rain, and wet snow, and not a single problem with rust.
When you get home and the gun is soaking wet, all I do is give it a quick wipe with some paper towel, and let it sit out to dry.
Once it is dry oil it up real good, and your ready for the next day.
The only guns in our group that I have seen an issue with are the Remington 870 Express's. A couple guys have had them go rusty all over, but I blame this on 2 things. Either they were not oiled up well since being bought, or before heading out, or the newbs who own them make the mistake of putting them in a bag, or case wet, and not letting it them dry.