U.S. Airmen assigned to the 307th Security Forces Squadron receive a safety briefing before dividing into groups at Fort Polk, Louisiana, Feb. 09, 2018. The Combat Arms Training and Maintenance Team led a class on how to safely operate a M240B machine gun and a M249 light machine gun. The Reserve Citizen Airmen fired more than 37,000 rounds in approximately five hours. (U.S. Air Force photo by Staff Sgt. Callie Ware/Released)