It's getting hoarded. Any place that doesn't have a per customer limit on purchases for 22 has people showing up as soon as the truck is unloaded and taking everything, for hoarding or resale at gun shows for ridiculous markups. It is still going on, too, it wasn't just in the immediate aftermath of SH.
And when people buy it all up and hoard it, that mentality spreads. When the guy who thought he only wanted to pick up one brick keeps trying and finding the shelves empty finally sees some in stock, he's going to stockpile as much as he can afford and that the store will let him.
