The NOAA situation was explained by the director of communications twice over:
Scott Mullen wrote:
Due to a clerical error in the federal business vendor process, a solicitation for ammunition and targets for the NOAA Fisheries Office of Law Enforcement mistakenly identified NOAA’s National Weather Service as the requesting office. The error is being fixed and will soon appear correctly in the electronic federal bidding system. The ammunition is standard issue for many law enforcement agencies and it will be used by 63 NOAA enforcement personnel in their firearms qualifications and training. NOAA officers and agents enforce the nation’s ocean and fishing laws to ensure a level playing field for fishermen and to protect marine species like whales, dolphins and turtles.
Scott Mullen wrote:
Also … you may be asking:
“Why so many rounds?”
Agents and officers are required to have 200 rounds in his or her duty bag, and twice-a-year firearm qualification and training calls for agents to use another 500-600 rounds. In addition, firearms instructors with more than one pistol may need more rounds in a year. In 2011, the guidance was that each agent and officer would need 700 rounds per year to meet these requirements.
“How many OLE personnel assigned firearms?”
111 special agents
23 enforcement officers
= 134 total
As to DHS, I'm guessing the explanation is similar, but with a heck of a lot more agents needing to qualify.