Lance Cpl. William Finn fires an M4 Carbine rifle during a training exercise at Camp Lejeune, N.C., Nov 16, 2016. The Marines practiced squad-sized movements to maintain unit readiness for their upcoming Integrated Training Exercise at the Marine Corps Air Ground Combat Training Center in Twentynine Palms, California. Finn is a grenadier with 1st Battalion, 8th Marine Regiment. (U.S. Marine Corps Photo by Lance Cpl. Jon Sosner) - Lance Cpl. William Finn fires an M4 Carbine rifle during a training exercise at Camp Lejeune, N.C., Nov 16, 2016. The Marines practiced squad-sized movements to maintain unit readiness for their upcoming Integrated Training Exercise at the Marine Corps Air Ground Combat Training Center in Twentynine Palms, California. Finn is a grenadier with 1st Battalion, 8th Marine Regiment. (U.S. Marine Corps Photo by Lance Cpl. Jon Sosner)

A round leaves the chamber of a Marine’s M4 carbine assault rifle during Expeditionary Operations Training Group’s close quarters tactics course before he switches to use his pistol at Camp Lejeune, N.C., Nov. 3, 2015. These drills tested the Marines with 2nd Reconnaissance Battalion’s ability to change between the two weapons systems, simulating a malfunction or depleting their ammunition. (U.S. Marine Corps photo by Lance Cpl. Dalton A. Precht/Released) - A round leaves the chamber of a Marine’s M4 carbine assault rifle during Expeditionary Operations Training Group’s close quarters tactics course before he switches to use his pistol at Camp Lejeune, N.C., Nov. 3, 2015. These drills tested the Marines with 2nd Reconnaissance Battalion’s ability to change between the two weapons systems, simulating a malfunction or depleting their ammunition. (U.S. Marine Corps photo by Lance Cpl. Dalton A. Precht/Released)