Gun cases are made to protect guns. Guns are tools, fine tools. They deserve to be cared for so they can be expected to perform to their design potential. Guns need regular maintenance, cleaning, repair, and proper storage. Storage implies both during the time of use and afterwards.
One of the purpose built survival weapons that I always found interesting was the M6 Scout made by Springfield Armory. Based on the design for the pilots of the USAF, the Springfield Armory M6 Scout has only a few changes from the original M6 Aircrew Survival Weapon.