Why Is The Postal Service Purchasing Ammo And Guns?

What is the story behind all these federal agencies that keep attempting to purchase small arms and ammo?
We’ve told you about these issues before… with DHS making huge purchase orders for ammo but this latest one is coming from the U.S. Postal Service
On January 31 of this year the USPS posted a solicitation to purchase “assorted small arms ammuntion” on the federal government’s federal business opportunities website (FBO.gov). The solicitation is structured to begin a bidding process for the purchase of guns and ammunition.
Why is the US postal service soliciting orders for small arms ammo? Is this not a fiscal sanity issue?