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.
Food is not just a source of energy and sustenance, but a comfort item as well. When you are hungry, morale goes down and chances of survival dwindle. There will be several opportunities to find food after the supermarkets close, you just need to know where to look and what tools to have.