"Why did Homeland Security"
Because every DHS member is required to recertify their ability to use a firearm every 3 months, and that means live-fire testing with 3 practice rounds beforehand... which works out at around ~200 rounds per member every 3 months.
Doesn't sound like much? 240,000 members... ~200 rounds a time... 4 times a year assuming no-one fails it and has to retake it... 192 million rounds used for just that per year.
But it gets better... the DHS runs
United States Citizenship and Immigration Services.
U.S. Customs and Border Protection: Law enforcement agency that enforces U.S. laws along its international borders
U.S. Immigration and Customs Enforcement: Law enforcement agency divided into two bureaus:
An agency that enforces U.S. laws while it investigates and gathers intelligence on national and international criminal activities that threaten the security of the homeland (Homeland Security Investigations); and an agency that investigates violations of the Immigration and Nationality Act and enforces the detention, deportation and removal of violators of United States immigration law (Enforcement and Removal Operations).
Transportation Security Administration: Responsible for aviation security
United States Coast Guard: Military service responsible for law enforcement, maritime security, national defense, maritime mobility, and protection of natural resources.
United States Secret Service: Yes, THAT Secret Service!
Federal Emergency Management Agency: agency that oversees the federal government's response to natural disasters like earthquakes, hurricanes, tornadoes, floods, forest fires, etc.
That lot uses a SHIT FUCKING TON of ammo every year... I wonder if they might just use all the ammo people are freaking out over on normal fucking stuff?!?