Okay, here is a possible explanation. Feel free to tear this up, because I honestly don't know exactly what DHS policy is, regarding live-fire training.

DHS (as of 2010) has roughly 220,000 employees. That's roughly 2045 rounds of ammo per employee for the next five years. So roughly 410 rounds per person per year.

Considering how much ammo I shoot off by myself per MONTH (about 1000-1500 rounds between pistol and rifle), 410 rounds for a YEAR is really not much at all.

Perhaps they are trying to do the smart thing and qualify their agents more than one or twice a year. I don't know, but I don't think we should look into this too far.