So again I ask you (because you ignored the question it would seem) what threat domestically are you speaking of?
Try to imagine. What would they be? I'm asking this because I cannot, for the life of me, imagine a threat where this much ammunition would be needed by a domestic entity other than exerting control over it's citizenry. I'd like to hear if you can, since you threw the idea of control over the citizenry out the window with your conspiracy commentary. So you must have an alternative that is far more logical. Please, by all means.
Five year delivery schedule, only 750 million rounds actual, and a significant price break on volume. This is nothing more than the Purchasing game.