Marine 0311 Rifleman vs 0331 Machine Gunner

0311 Rifleman and 0331 Machine Gunner both live inside the 03 infantry field, and both start with the same promise: every Marine is a rifleman. After Boot Camp and the School of Infantry, the two jobs split.

The rifleman fights through fire and maneuver as part of a fire team. The machine gunner owns the crew-served weapons that pin the enemy down so maneuver can happen.

Quick Comparison

Treat this as a fork, not a ranking. Neither job is the junior version of the other. Both pull from the same infantry accession pool, deploy on the same battalion and Marine Expeditionary Unit cycles, and put you outdoors carrying weight for a living.

The differences that decide the choice sit in three places:

• The weapon you run: an individual rifle, or the crew-served machine guns that a team feeds and moves.
• The schoolhouse that awards your MOS: one infantry school, or that school plus a second course.
• The ASVAB bar you clear: the standard enlistment baseline, or a specific line score on top of it.

Each of those gets its own section below.

The rifleman is the high-volume core of the infantry, so access is more predictable. The machine gunner is a specialist slot with fewer seats and a real test-score filter, so the door can close earlier.

That single difference is why the choice is worth making before you walk into the recruiting station, not after. Get it right and you spend four years in the job you wanted. Get it wrong and you are locked into a contract that does not fit.

To go deeper on either job, read the 0311 Rifleman profile or the 0331 Machine Gunner profile. Both sit inside the 03 Infantry field, alongside the other 03XX roles you can weigh before you commit.

What Each Marine Actually Does

Both jobs share the infantry baseline of patrols, field exercises, and daily weapons maintenance. What changes is the weapon at the center of the work.

The Rifleman’s Role

The 0311 Rifleman is the primary ground combat specialist. The job is to locate and destroy the enemy through fire and maneuver, defend ground, and operate inside a fire team or rifle squad.

A typical training day runs through individual movement techniques, marksmanship, land navigation, patrol planning, and physical conditioning. In the field, that becomes combat patrols, ambushes, raids, observation post duty, and objective clearance.

The Machine Gunner’s Role

The 0331 Machine Gunner is the infantry’s sustained direct-fire specialist. The job is to employ light, medium, and heavy machine guns and their support vehicles for rifle squads, platoons, and companies.

During an assault, the gun team pins the enemy while riflemen maneuver. On defense, the guns anchor fire lanes and force the enemy into channels where they can be destroyed.

The weapon each Marine answers for is the cleanest way to see the split:

• 0311 Rifleman: the M27 Infantry Automatic Rifle, M16A4, and M4 carbine, plus grenades, optics, and assigned crew-served weapons as directed.
• 0331 Machine Gunner: the M240B medium machine gun, M2 .50-caliber heavy machine gun, and Mk 19 grenade launcher, plus the HMMWV variants used to move those guns.

The gun changes the daily rhythm. A rifleman maintains a personal weapon. A machine gunner field-strips, cleans, and function-checks crew-served systems every day, runs crew drills for emplacement and displacement, and maintains the vehicles that carry the guns.

The M249 Squad Automatic Weapon turns up in both worlds depending on the billet, but the machine gunner is the one who owns the medium and heavy guns as a primary job. Every other infantry specialty builds on the rifleman baseline, which is why 0311 is the foundation the field stands on and 0331 is one of the specialties that grows out of it.

Qualification Gates

This is where the two contracts stop being interchangeable. Both jobs use the ASVAB to set eligibility, and both require the standard active-duty AFQT minimum of 31 for high school diploma holders. The line-score bar is what separates them.

The 0311 Rifleman has no published standalone line-score cutoff. Meeting the Marine enlistment baseline keeps you eligible, which is part of why riflemen are easier to contract.

Machine Gunner Score Requirement

The 0331 Machine Gunner requires a line score of EL, GT, or MM at 90. The Marine Corps lets you qualify on any one of those three composites, because each measures a slice of the mechanical and technical aptitude that running crew-served weapons demands.

That flexibility matters: a strong score in any one of general aptitude, electronics, or mechanical maintenance is enough on its own. A rifleman contract does not test for it at all, so the machine gunner contract is the first place in the infantry where your ASVAB subtests, beyond the AFQT, decide whether you qualify.

Here is what those three composites are built from:

The 0331 adds one gate the rifleman does not face: the WS-B water survival qualification.

Your ASVAB score is what opens or closes the machine gunner door before your fitness ever gets tested. A rifleman contract forgives a softer score. A machine gunner contract does not.

If 0331 is the target, the academic work is the gate, so build it early with the ASVAB guide and walk into the recruiting station with the line score already in hand.

Training Path

Both pipelines start identically and then diverge at one school. Every infantry Marine moves through Boot Camp and the School of Infantry.

The rifleman’s MOS is awarded at Infantry Training Battalion. The machine gunner earns the MOS one school later.

Infantry Marines do not attend Marine Combat Training. They move straight from Boot Camp into Infantry Training Battalion, which is the MOS-producing school for every 03XX field.

Rifleman Finish Line

For the 0311 Rifleman, that is the finish line. The course covers movement techniques, marksmanship, land navigation, patrolling, and direct-action work, and the rifleman MOS is awarded at the end.

The 0331 Machine Gunner keeps going. After Infantry Training Battalion, future machine gunners attend the Machine Gunner Course, where M240B, M2 .50-caliber, and Mk 19 employment, crew drills, and direct-fire fundamentals are taught.

The MOS is awarded when that course is complete. That extra schoolhouse is the structural reason 0331 is a specialist track and 0311 is the infantry baseline.

Follow-On Schools

Both fields open more schools later. A rifleman can compete for advanced courses such as the Scout Sniper Basic Course, which leads to the 8541 Sniper designation. A machine gunner can move up through the Advanced Machinegun Course and small-unit leaders courses.

The Marine Corps also runs leadership schools such as Corporal’s Course for both fields. Those follow-on schools come after the fleet, not before the MOS, so they do not change which contract you sign today.

Physical Load, Risk, and Work Setting

Both jobs are physical, and both carry the highest direct combat risk in the Marine Corps. The difference is weight and where it sits on your body.

A rifleman carries between 60 and 100 pounds of gear on combat patrols and spends the work cycle walking, running, low-crawling, and climbing in field conditions. A machine gunner carries more.

Crew Weight and Load Distribution

The M240B alone is 27 pounds, and the heavy machine gun mounts, tripods, and ammunition cans add significant load on top of a normal combat kit. Sustained-fire work stays demanding even from a supported position.

The weight is also shared across the crew. A gun team splits the system, ammunition, and mounts among the gunner, assistant gunner, and ammo bearer, so the job depends on every Marine carrying a piece of it.

Where each Marine works also shifts:

• 0311 Rifleman: fire teams and rifle squads working outdoors in field environments, on training ranges, and in deployed settings.
• 0331 Machine Gunner: weapons platoons inside infantry battalions and weapons companies, with range time, vehicle operations, and heavier maintenance cycles filling most non-garrison days.

The maintenance load is a permanent difference. A rifle needs upkeep. Crew-served weapons need constant attention to stay reliable, so machine gunners spend extra hours on the guns and their vehicles before and after every field event.

Both fields run the same PFT and CFT standards and share the same hazards: direct combat exposure, hearing loss from weapons fire, musculoskeletal strain from heavy loads, and heat or cold injury in the field. Neither job requires a security clearance at the entry MOS level, and the duty stations overlap, centered on Camp Pendleton, Camp Lejeune, Hawaii, and Okinawa, with Twentynine Palms adding combined-arms work for weapons units.

Career Progression and Deployment

The rank timeline is nearly identical, which is worth knowing so you do not over-weight it. Both jobs promote through the same enlisted grades on roughly the same schedule. What differs is the billet each rank points you toward.

• 0311 Rifleman: team member as a junior Marine, fire team leader around Corporal, rifle squad leader around Sergeant, then platoon sergeant and senior staff NCO billets.
• 0331 Machine Gunner: ammo bearer and assistant gunner early, gunner and gun team leader around Corporal, gun section leader around Sergeant, then weapons platoon sergeant and company billets.

Deployment Tempo

Deployment tempo is shared. Both jobs run at standard infantry tempo, roughly one seven-month deployment every 24 to 36 months, including Marine Expeditionary Unit rotations that put Marines on ship for six to seven months.

The machine gun weapons platoon deploys as an integral part of the rifle battalion, so the two jobs ship together. Junior Marines in both jobs hold limited individual authority until they earn a leadership billet, so early on you execute your assigned role and prove yourself before you lead one.

Lateral moves open to both after the initial obligation, with command endorsement and an available school seat. Riflemen commonly move into reconnaissance or military police. Machine gunners often carry their weapons handling and small-unit leadership into law enforcement, security, or instructor billets.

The infantry experience itself, more than the specific MOS, is what civilian employers in policing, security, and emergency response tend to value.

Which One Fits You

Both jobs demand high physical performance and a clean record. The 0331 line score is the one hard academic gate that separates them on paper. The rest of the choice is about what kind of infantry Marine you want to be.

0311 Rifleman

Choose it if you want the most direct ground combat role and you are motivated by tangible accomplishment outdoors. The rifleman is the easier contract to get and the broadest infantry foundation to build on.

• Best fit: physically competitive, comfortable in hard outdoor conditions, team-oriented without needing to be carried.
• Poor fit: you want a predictable schedule, prefer working alone, value personal comfort, or want a civilian job skill from day one.

0331 Machine Gunner

Choose it if you want to master a heavy weapon system inside a tight gun team and you have the mechanical aptitude to keep equipment running under field conditions. The seats are fewer and the test bar is higher, so plan for it early.

• Best fit: you want weapons mastery, enjoy field work with an interdependent crew, and accept the maintenance that comes with the guns.
• Poor fit: you dislike carrying heavy gear, repetitive maintenance, or weapons-specific team structures.

If both still appeal, let the ASVAB decide the order. Clear the EL, GT, or MM 90 line score and both doors stay open, which gives you the most room to negotiate the contract you actually want.

More Information

Before you choose between 0311 and 0331, get the ASVAB handled, because the line score decides which door is open. Start with the ASVAB study guide for the line-score basics and a prep plan, then talk with a Marine Corps recruiter about current 03 infantry contracts and Machine Gunner Course seat timing.

Explore more in the 03 Infantry field, compare the full 0311 Rifleman and 0331 Machine Gunner profiles, or browse the rest of the Marine Corps guides for more decision-stage comparisons.