Sgt. Jansen Davis, a section chief with 3rd Platoon, Rocket Battery F, 2nd Battalion, 14th Marine Regiment, 4th Marine Division, Marine Forces Reserve, records the serial numbers and launch codes of Guided Multiple Launch Rocket Systems munitions during Weapons and Tactics Instructor course 1-18 at Landing Zone Bull Attack, near the Chocolate Mountain Aerial Gunnery Range, California, Oct. 11, 2017. Marines are preparing for future exercises and deployments by maintaining proficiency with the M142 High Mobility Artillery Rocket System and its functions. (U.S. Marine Corps photo by Lance Cpl. Melany Vasquez/ Released)