So, let's see...in addition to this order for explosives the feds have ordered or purchased 1.4 billion rounds so far; there are 311 million people in the US.
Which depts?

Dept of Education
Dept of Forestry
Dept of Agriculture
National Weather Service
Social Security Admin
FBI
IRS
TSA
DHS

In addition, DHS officials have purchased 9,300 bulletproof checkpoint booths, which many expect will be used on U.S. highways and will be under the control of the Transportation Security Administration, an agency inside the DHS. These booths will be used to monitor the flow of travelers from one point to another.

"Safer by the round"