U.S. Marine Corps Lance Cpl. Michael J. Pettay, a crew chief with Marine Heavy Helicopter Squadron 461, conducts a weapons check on a GAU-16/A .50 Caliber Machine Gun before an operation at Camp Bastion, Helmand province, Afghanistan, July 22, 2013. The operation was conducted in support of the International Security Assistance Force and North Atlantic Treaty Organization. (U.S. Marine Corps photo by Cpl. Ashley E. Santy/Released)