Seen at moonbattery.com:
The US Post Office is not a law enforcement agency. So why does it need assorted small arms ammunition?
Oh, I get why. For the same reason that the National Oceanic and Atmospheric Administration needs 72,000 rounds of .40 caliber ammo, the National Weather Service needs 46,000 rounds of the same, the Social Security Administration needs 174,000 rounds, and the Department of Education needs to blow $80,000 on Glocks and $17,000 on shotguns.