I know our local Walmart sporting goods guys pretty well. They generally put it all out on the glass shelves - generally. It comes in late afternoons on trucks, is put on the shelves late evenings for the next day. Sometimes the night people don't put it all out for several reasons, one they are too lazy to look for it, two they know someone who will come in later the next day or two to buy it. They figure out of sight is out of mind knowing all along they have someone in mind who wants to buy it.
When I am on the road I hit several Walmarts and the only ammo I can't find now is 380. Everything else is in huge supply here in Kansas. Not always the types or sizes of bullets I shoot but plenty of ammo - way plenty.