I've put 2 of these on my shotguns. They don't hold moisture and there is no residue leftover if you decide to remove it later down the road. They are quality vinyl that adhere perfectly to your gun as long as you take your time during the application process. Preparation is done by disassembly and degreasing the parts with non chlorinated carb cleaner. Get yourself a a heat gun, a good sharp little xacto knife, and a credit card or driver's liscence to push material into small places.
https://www.gunskins.com/products/shotgun-skinPM me if you decide to go this route and I'll be happy to help you in any way I can.
