|A .223 round|
It's kinda hard to get a handle on how much ammo DHS is actually trying to buy from the RFPs it issued this year. DHS apparently uses several .223 variants. A far better picture is derived when actual contracts are awarded, provided DHS manages to attract an acceptable bidder for a long term contract.
We do know for certain the agency cut a deal to buy up to 450 million .40 caliber pistol rounds earlier this year. We also know that five year deal was for more than twice as much ammo as a multi-year contract the agency awarded in 2009.