U.S. Marine Corps Lance Cpl. Michael Ohara, a field

U.S. Marine Corps Lance Cpl. Michael Ohara, a field artillery cannon crewman with Battery I, 3rd Battalion, 12th Marine Regiment, cleans the breach of an M777 Lightweight 155mm Howitzer prior to firing it during 11th Marine Regiment's Desert Fire Exercise aboard Marine Corps Air Ground Combat Center Twenty Nine Palms, Calif. April 26, 2013. 11th Marines conducted an artillery desert firing exercise to maintain their combat proficiency via realistic combat scenarios. (U.S. Marine Corps photo by Lance Cpl. James Mast, 1st Marine Division Combat Camera/ Released)