AlliantTechsystems took over the Lake City Army Ammunition Plant from Winchester, and since Bill CLinton made it illegal for us to buy surplus ammo, Federal (ATK) doesn't run the XM193 through military testing and therefore we can have it. Note the X in XM193?
Federal also announced that this will be a regular product, and they are already up to Lot 22 last I heard. I saved my Lot-1 and Lot-3, and have a boatload of Lot-10.
It is hot stuff, and it is up to M193 Mil-Spec, just not tested for it.
There shouldn't be any shortages of this. Israel Military Industrties also supplies out boys with M855M856 over in the Mid East-as this is the primary issue of 5.56mm ammo.