U.S. Air Force Staff Sgt. Stephans Doherty, 447th Expeditionary Aircraft Maintenance Squadron aircraft armament systems journeyman, sprays sealant onto the barrels of a GAU-8/A Avenger rotary cannon April 5, 2017, at Incirlik Air Base, Turkey. The barrels were sealed to prevent weathering during use. (U.S. Air Force photo by Airman 1st Class Devin M. Rumbaugh)