What is the reason for this?
This case serves as a good measuring stick. Stop consuming media from any source you see peddling this nonsense.
Note this critical fact...it's
not an order for 450 million bullets.
In the government contracting business this is called a "BPA" or "Blanket Purchase Agreement". The purpose is to reduce paperwork for both the purchasing agency and the contractor. Agencies like BPAs because they only have to negotiate specifications one time, and because it forces the contractor to prove they can supply that capacity (100 bulldozers, 12,000 data entry clerks, etc.). Contractors like them because they are guaranteed a revenue stream for the next five years. They can show that to banks to get better financing.
Stop worrying about what fascists in D.C. do. Hysterical exaggeration does not advance Freedom. Anyone who has studied history knows what fascists desire. Aldous Huxley's book
Brave New World will give you a short, easy-to-read overview.
http://archive.org/details/BraveNewWorld_262Teaching friends and children to be free by
demonstrating it is a much better use of your few minutes on this earth.