Master Gunnery Sergeant Master Gunnery Sergeant ( MGySgt ) is the ninth and highest enlisted rank ( along with the grade - equivalent ranks of Sergeant Major and Sergeant Major of the Marine Corps ) in the United States Marine Corps . Master Gunnery Sergeants are senior staff non - commissioned officer s ( SNCOs ) , and are assigned a pay grade of E - 9 . Master Gunnery Sergeants are sometimes referred to by the nickname " Master Guns " , " Master Gunny " , or " Top " . These nicknames are unacceptable in formal or ceremonial situations , and , at the rank holder ' s discretion , may also be unacceptable for use by lower - ranking Marines . The Master Gunnery Sergeant insignia consists of a bursting bomb ( colloquially referred to as a " pineapple " due to the similarity of its appearance as stylized ) centered vertically between three chevrons and four rockers . History . The grade was derived from another grade unique to the United States Marine Corps , the Gunnery Sergeant , and has been in use ( though not continuously ) since the time of the Spanish – American War ( April 25 – August 12 , 1898 ) . Establishment of the grade in its current form and paygrade occurred during sweeping reorganization of grades and paygrades in 1958 and 1959 . The grade was included , along with the grade of Master Sergeant , in a new program for the paygrades of E - 8 and E - 9 which allowed senior SNCO billets to be filled by occupational specialists . This move was designed to officially acknowledge the ever - increasing complexity of modern warfare , while still maintaining the First Sergeant and Sergeant Major programs , with their historic command prestige . During and prior to World War II , this was reversed ; the Sergeant Major was an administrative position while the Master Gunnery Sergeant was part of the S - 3 section and enforced discipline . Modern role . Master Gunnery Sergeants ( MGySgts ) with an infantry 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 , 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 / 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 an Aviation Maintenance MOS serve in the billet of Maintenance NCOIC / Chief in the Aircraft Maintenance Department of a Marine aircraft squadron . In their annual performance evaluations , called " fitness reports " , eligible Gunnery Sergeants indicate whether they wish to be considered for 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 grades is that Master Gunnery Sergeants retain their MOS , while Sergeants Major are given a new MOS to reflect their general command focus . This reinforces the Master Gunnery Sergeant ' s role as a provider of military leadership , technical acumen , and mastery of their MOS .