U.S. Marine Corps Sgt. Darrin Smith, a crew chief with Marine Light Attack Helicopter Squadron 775, Marine Aircraft Group 41, 4th Marine Aircraft Wing, operates a GAU-21/A during a live-fire event at Cold Lake Air Weapons Range, Alberta, Canada, June 15, 2019, in support of Sentinel Edge 19. The Marine Reserve plays a critical component to the Marine Corps’ Total Force, and training such as SE19 helps ensure Reserve units combat effectiveness and proficiency for world-wide deployment. (U.S. Marine Corps photo by Lance Cpl. Jose Gonzalez)