Panic buying is contagious. When Joe Bob goes to his favorite store to buy his yearly box of deer ammo and can't find it, he then goes all over town looking. If he finds something in his preferred cartridge, he buys 4 boxes instead of his usual 1 box. Then he tells everyone he knows that ammo is hard to find, so they run all over town and buy 3 or 4 boxes that they usually would not have. And so demand grows exponentially and pretty soon the shelves are bare. Then you have the hoarders (who think the 10,000 rounds in their closet isn't enough) and re-sellers that line up outside of the box stores at 6 am on shipment day and buy anything they can get their hands on.
