U.S. Army paratroopers fire an M777A2 cannon during a firing demonstration for visiting Command Sgt. Maj. William Johnson, ISAF - Joint Command command sergeant major, on Forward Operating Base Shank in Logar province, Afghanistan, July 12, 2012. The paratroopers are assigned to Battery A, 4th Battalion, 319th Airborne Field Artillery Regiment, 173rd Airborne Brigade Combat Team and are on their 4th deployment to Afghanistan in support of Operation Enduring Freedom. U.S. Army photo by Spc. Michael Sword