The Marine Corps Exchange at Quantico has guns and ammo. You have to ask for the ammo, handguns and rifles are displayed. My wife missed the .380 shipment or else it didn't come in, so they're currently taking email addresses and letting people know when the ammo that they want comes in.
Maybe it's a Marine thing? I've only been in Navy and Marine ones and the Navy ones back in Washington didn't have guns or ammo. The MCX here has stacks of AK mags, AR mags, combat shotguns, and recently restocked pistols. They're still out of ARs and AKs though usually stock them.