Primary Responsibilities
Employ Marine Corps machine guns and supervise machine-gun teams and sections.
03xx Infantry / Marine Corps MOS Profile
0331 Machine Gunner
Machine Gunners employ medium and heavy machine guns to support infantry units with suppressive, protective, and sustained fires.
Code / Pipeline0331
MOS NameMachine Gunner
Category03xx Infantry
Unit Association3/5 / 2nd Recon / Force Recon
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Marine Corps MOS Profile
Responsibilities and Pipeline
Training Pipeline
Complete entry-level infantry training and machine gunner instruction.
Billet Progression
This MOS sits inside the Marine ground-combat lane and depends on field discipline, small-unit leadership, communications, weapons proficiency, and repeated field evaluation.
Current Member Tracking
The Current Members section below is populated from command-record MOS data. When a chain of command changes MOS, this page is regenerated to keep the roster link accurate.
USMC Responsibilities
0331 Machine Gunner is described here by practical Marine Corps duties, billet expectations, and training progression. This section avoids game-language so the page reads like a professional MOS reference.
- Employ Marine Corps machine guns and supervise machine-gun teams and sections.
- Plan support-by-fire positions, rates of fire, target reference points, ammunition, and gun displacement.
- Maintain crew-served weapons, tripods, optics, range cards, and ammunition accountability.
- Integrate machine guns with maneuver, fires, and security plans.
Training Pipeline
The pathway is shown at a broad public level. Exact prerequisites, screening, quotas, course names, and assignments can change by fiscal year, manpower requirement, medical qualification, command screening, and schoolhouse policy.
- Complete entry-level infantry training and machine gunner instruction.
- Serve in weapons platoons, rifle companies, reconnaissance units, or weapons companies.
- Develop as assistant gunner, gunner, team leader, section leader, and weapons platoon staff.
- Complete advanced infantry and leadership training as assigned.
Billets And Skill Growth
- Entry-level Marines focus on core tasks, equipment, field discipline, and reliable execution.
- NCOs supervise small teams, enforce standards, plan rehearsals, and train junior Marines.
- SNCOs and officers manage readiness, risk, training plans, inspections, reporting, and integration with adjacent staff sections.
- Instructor and staff billets preserve standards, document lessons learned, and build repeatable training for the next rotation.
Chain of Command Matching Logic
Chain of command records can list a current MOS, prior record MOS, ADMOS, or specialty track. This page shows a member as a Current MOS when the MOS is the member’s active specialty and as Recorded Profile MOS / ADMOS when it appears in the member history.
Rank / Grade Requirements
Grade LaneEnlisted MOS
Entry / Award Basis
Machine gunner MOS after recruit training and infantry weapons training.
Typical Rank Use
Pvt through Sgt for gunner, team, section, and squad-level weapons billets; SSgt through MGySgt for weapons platoon, company, and infantry operations billets.
Schoolhouse & Qualification Requirements
SchoolhouseSchool of Infantry / Advanced Infantry Training Battalion / Reconnaissance Training Company as applicable
Recruit training, Marine Combat Training or Infantry Marine Course path, then MOS-specific infantry, reconnaissance, scout sniper, weapons, or leader training.
Entry QualificationsScreening / Prerequisites
Must meet infantry screening standards, weapons/field prerequisites, swim or reconnaissance screening where required, medical eligibility, security requirements, and command endorsement for advanced schools.
Associated SchoolsFollow-On Training
- Basic Reconnaissance Course / reconnaissance training pipeline when assigned
- Basic Airborne Course for parachutist-qualified billets
- Military Free-Fall when billet-qualified
- Marine Combatant Diver / dive supervisor track when assigned
- SERE Level C for designated high-risk or special-operations-associated billets
- Scout Sniper / advanced marksmanship schools where applicable
Course titles, quotas, prerequisites, and sequence can change by fiscal year, manpower requirement, medical qualification, and current schoolhouse policy.
Current Members in this MOS
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MOS Association
3/5 / 2nd Recon / Force Recon
This page links the occupation lane to 3/5, 2nd Recon, and Force Recon pathways. Matching chain of command members appear in the Current Members section above.