I guess there is no contradiction between what I said and what you say. The demand for guns may have skyrocketed, but guns still weren't the most popular thing to trade at all, at least between regular people (as opposed to organized crime group firearm suppliers). So if a regular person wanted to go buy some food or clothes and wanted to trade something for it, guns or ammo weren't the most popular trades, nor the safest ones. If you offer ammo in exchange for food, most people would refuse, and those who accept are pretty likely to kill you instead of paying.