Relatively speaking, 450 million rounds is not a heck of a lot. Here is the US Army common ammunition consumption rates over the course of the decade. Even in peacetime, consumption for training is enormous.
http://www.almc.army.mil/alog/issues/SepOct10/Story_Images/ch704_1.jpg
There are about 200,000 employees of DHS.
What is important is that DHS is inherently dangerous for a really stupid reason: they are an agency that has no realistic reason to exist, so they are thrashing around, trying to find a mission, any mission, before they are put on the chopping block.
The hazard this entails should not be underestimated, because it is bureaucrat scoundrels desperate to keep their phoney-baloney jobs. And they don’t care who they have to hurt to do so.
That’s 2,250 rounds _each_.
And most of ‘em won’t be getting _any_.
