The Department of Homeland Security's (DHS) mission includes law enforcement elements, which require the department, through its components, to manage various types of firearms. DHS's annual ammunition purchases have declined since fiscal year 2009 and are comparable in number to the Department of Justice's (DOJ) ammunition purchases. In fiscal year 2013, DHS purchased 84 million rounds of ammunition, which is less than DHS's ammunition purchases over the past 5 fiscal years. DHS component officials said the decline in ammunition purchases in fiscal year 2013 was primarily a result of budget constraints, which meant reducing the number of training classes, and drawing on their ammunition inventories. This book addresses trends in DHS's ammunition purchases since fiscal year 2008, how DHS's purchases compare with DOJ's, and what factors affect DHS's purchase decisions.