I may be a bit ignorant but why would the USDA need guns?
The Office of the Inspector General is the law enforcement branch of the USDA:
The Office of Inspector General was legislatively established in 1978 with the enactment of the Inspector General Act (Public Law 95-452). The act requires the Inspector General to independently and objectively:
- Perform audits and investigations of the Department's programs and operations;
- Work with the Department's management team in activities that promote economy, efficiency, and effectiveness or that prevent and detect fraud and abuse in programs and operations, both within USDA and in non-Federal entities that receive USDA assistance;
- Report OIG activities to the Secretary and the U.S. Congress semiannually as of March 31 and September 30 each year;
We accomplish this mission by:
- investigating allegations of fraud and abuse;
- using preventive audit approaches, such as reviews of systems under development;
- conducting audits of the adequacy and vulnerability of management and program control systems; and
- auditing the adequacy of large USDA payments, such as insurance and deficiency payments, major loans, and retailer food stamp redemptions.
Taken from the
USDA OIG website.
Basically, their office is staffed with GS-1811s (Criminal Investigators/Special Agents), with the authority to conduct investigations and make arrests. The firearms are carried pursuant to that authority.