Door Gunner Marine Corps Sgt. Caleb Bastille operates a .50-caliber heavy machine gun during in support of Weapons and Tactics Instructors course 2-18 at Marine Corps Air Station Yuma, Yuma, Ariz., April 2, 2018. Bastille is a crew chief. Marine Corps photo by Cpl. Nathaniel S. McAllister SHARE: Download: Full Size (1.62 MB) Tags: marines, northcom, northern command, training, marine corps Credit: Cpl. Nathaniel McAllister VIRIN: 180402-M-FJ661-0037A.JPG Photo Gallery