It's not simply a run on ammunition, Federal (ATK Space Systems) have substantial contracts with the Government that get priority.
Imported ammunition, and other manufacturers besides these will be available first. http://www.brownells.com/aspx/learn/...aspx?lid=15832
http://www.defenseworld.net/go/defensenews.jsp?n=ATK%20Receives%20$266M%20Contrac t%20for%20caliber%20ammunition%20from%20US%20Army& id=6897
The press release you see here is from May, and I can't find ther Bizopps contract, but this is where the ammo is.