 Additionally, Gunnery Sergeants are platoon sergeants for the Combined Anti-Armor Team, heavy machinegun platoon, or anti-armor platoon.Master Sergeants in this Military Occupational Specialty serve in the weapons company as the Company Operations Chief, or in the battalion operations section (S-3).An infantry Master Gunnery Sergeant serves as the unit Operations Chief for an infantry battalion or higher (regiment, division, etc.)