Editing Master gunnery sergeant (section)

==Modern role==
Master gunnery sergeants (MGySgts) with an infantry [[List of United States Marine Corps MOS|Military Occupational Specialty]] (MOS) serve in the billet of operations chief, as the senior staff non-commissioned officer in the operations section of an infantry battalion, or higher level (e.g., MEU, infantry regiment, MEB, Marine division, or MEF) headquarters. MGySgts with a non-infantry (e.g., artillery, tank, communications, logistics) MOS typically serve as either the operations chief of their MOS type battalion/regiment (e.g., artillery battalion/regiment, tank battalion) or as the section chief/[[Non-Commissioned Officer in Charge|NCOIC]] in their MOS related staff section (e.g., communications, logistics) at the regimental/Marine Aircraft Group, or higher level, headquarters. Master gunnery sergeants with the Military Police MOS serve in the billet of provost sergeant in the Provost Marshal's Office.

Master gunnery sergeants with an aviation maintenance MOS serve in the billet of maintenance NCOIC/chief in the aircraft maintenance department of a Marine aircraft squadron or in maintenance-related billets at the Marine Air Group (MAG) or Marine Air Wing (MAW) level. For example, there are four aviation-related MGySgt billets (aircraft maintenance NCOIC, aviation supply NCOIC, avionics NCOIC, and aviation ordnance NCOIC) in the Marine Aviation Logistics Squadron (MALS) organic to each Marine Aircraft Group (MAG).

In their annual performance evaluations, called "fitness reports", eligible gunnery sergeants indicate whether they wish to be considered for [[Promotion (rank)|promotion]] to [[master sergeant]] or [[first sergeant]], and thus whether they enter the promotional track for master gunnery sergeant or [[sergeant major]]. Once promoted, the promotional track is usually permanent, with lateral movement between the two programs very uncommon. 

One of the major differences between the two E-9 ranks is that master gunnery sergeants retain an occupational field-related MOS, while sergeants major receive a new MOS to reflect their specific command-related focus. This reinforces the master gunnery sergeant's role as a provider of military leadership, technical acumen, and mastery of their MOS. It is also important to note that while a sergeant major and a master gunnery sergeant have different duties and responsibilities, a master gunnery sergeant can (and often does) assume the duties of a sergeant major. The reverse is rarely possible.