Infantry Weapons Officer
The United States Marine Corps MOS 0306, Infantry Weapons Officers, commonly referred to as "The Gunner" or "Marine Gunner" are non-technical Chief Warrant Officers that are weapons specialists and are knowledgeable in the tactical employment of all the weaponry in Marine Corps arsenal - all weapons organic to the Marine infantry units.
The requirements to apply for selection are very stringent and much higher than what is needed for other warrant officer appointments. For example; minimum time in service is sixteen years vice eight, and minimum rank to apply is Gunnery Sergeant (E-7) vice Sergeant (E-5). They are not appointed Warrant Officers, but rather commissioned directly to the grade of Chief Warrant Officer-2 and are the only officers who are officially designated the title, "Marine Gunner" and authorized to wear the "Bursting Bomb" insignia.
The title "Gunner" is almost always used in lieu of rank (i.e., "Gunner Smith" as opposed to "Chief Warrant Officer Smith"), and the rank insignia worn on the left collar is replaced with a "Bursting Bomb", a larger "Bursting Bomb" insignia is worn 3/4" above the rank insignia on both shoulder epaulets when a coat is worn. Occasionally other warrant officers are referred to as "Gunner" but this is incorrect and typically done out of laziness or ignorance.
The Gunners' technical skills complemented with infantry field experience fundamentally posits them as advisers to the force commanders within the Fleet Marine Force's task forces (i.e. Marine Expeditionary Force (MEF) and its subordinate units). Marine Gunners may be responsible for developing and monitoring weapons training protocols, tactical employment of weapons, preventive maintenance of the unit's infantry weapons, management of the units ammunition allocation—and the unit training plan, infantry training, and fire support planning. Additional assignments may be based on future needs of the Marine Corps; such as new weapons systems acquisition, new weapons systems research and development.
During combat operations, Marine Gunners assists their force commanders in battle tracking; They are sent forward to oversee the battle, reporting directly to task force commanders in a "directed telescope" fashion.