A Marine with Weapons Company, 2nd Battalion, 2nd Marine Regiment, fires on virtual targets with an Mk-19 automatic grenade launcher during training at the Indoor Simulated Marksmanship Trainer aboard Camp Lejeune, N.C., Aug. 5, 2015. The ISMT—used to train Marines on Mk 19s, M2 50-caliber machine guns, M240 medium machine guns and M16 service rifles—will be part of the Marine Corps Systems Command display at Sea Air Space May 16-18. (U.S. Marine Corps photo by Cpl. Sullivan Laramie) - A Marine with Weapons Company, 2nd Battalion, 2nd Marine Regiment, fires on virtual targets with an Mk-19 automatic grenade launcher during training at the Indoor Simulated Marksmanship Trainer aboard Camp Lejeune, N.C., Aug. 5, 2015. The ISMT—used to train Marines on Mk 19s, M2 50-caliber machine guns, M240 medium machine guns and M16 service rifles—will be part of the Marine Corps Systems Command display at Sea Air Space May 16-18. (U.S. Marine Corps photo by Cpl. Sullivan Laramie)