I was at the local Wal-mart today, looking at the non-existant ammo selection. The clerk pointed out that they have implemented a new policy starting this week that limits ammo purchases to six boxes.
According to the clerk, Wal-Mart has had alot of gun dealers buying every bit of ammo in stock, the new policy was put in place to make ammo available to more customers. I asked, and he said this is a company wide policy.