Marine Corps machine gunners are assigned with the MOS 0331.
They are responsible for the deployment, care, mounting, and unmounting of heavy machine guns.
The Marine Corps uses three primary heavy machine guns.
These machine guns are primarily the M240B which uses 7.62 mm ammo, the 50-caliber machine gun, and the 40 mm heavy machine gun.
The primary mission of these machine guns is to provide overwhelming firepower while in a firefight or while suppressing an enemy position.
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While on foot patrol, these Marines will carry the M240B in support of infantry platoons or light armored reconnaissance units.
On convoys, the machine gunners are responsible for mounting and utilizing heavy machine guns in the form of 50-caliber or 40 mm heavy machine guns.
Machine gunners are usually referred to as “31s” by the other infantry Marines in their platoon or battalion.
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0331 Requirements and Qualifications
- Be a U.S. Marine
- Complete the machine gunner course at the school of infantry, East or West Coast
- Have a GT score of 90 or higher
0331 Training and Career Path
Machine gunners are trained infantrymen who specialize in heavy machine guns.
They attend the same infantry school as basic riflemen but spend more time focusing on tactics used with heavy machine guns.
These Marines will thoroughly study and understand fire team tactics and maneuvers that are better suited for machine gunners.
The major difference is that machine gunners will work in small teams of two to three Marines and utilize overwhelming firepower to destroy and suppress enemy positions.
While attending school, Marines in this MOS will thoroughly review positioning on the battlefield where machine guns can be positioned to provide the most effective firepower against enemy positions.
Additionally, the school will consist of learning how to feed and clear heavy machine guns.
Given the rate of fire, these weapon systems are more susceptible to jams and overheating than a standard M16 or M4 assault rifle.
Therefore, it is imperative that machine gunners are experts in feeding, reloading, clearing jams, and replacing hot barrels.
Barrels will be regularly replaced during the use of various machine guns, so these Marines must be masters at replacing these barrels in order to generate a sustained rate of fire against the enemy.
Following school, machine gunners will be assigned to an infantry battalion where they will advance their field tactics and continue to review and maintain various heavy machine guns.
Furthermore, 0331 Marines will spend a significant amount of time in the field and practicing tactics while preparing for a fairly steady stream of deployments during their time as active duty Marines.
How Much Are 0331’s Paid?
0331 Marines receive the same base pay as every other enlisted military member.
This is a standard rate that is the same across all branches of the military.
Base pay is easy to find through a quick web search, but a few ranks, with their time in service, will be provided below.
Machine gunners will receive additional pay while deployed or in areas where hazard pay is approved.
Aside from that, 0331 Marines are not eligible for any special pay incentives.
In addition to the base pay, machine gunners, and all Marines, receive free medical, dental, and vision insurance.
They also receive at least two meals per day and free room and board.
Although the base pay may seem low, these other incentives more than make up for it.
Check out our pay chart for the Marine Corps enlistees below:
| Insignia | Pay Grade | Rank | Abbreviation | 2023 Minimum Monthly Pay |
|---|---|---|---|---|
| E-1 +4 months | Private | Pvt | $1,917.60 | |
 | E-2 | Private First Class | PFC | $2,149.20 |
 | E-3 | Lance Corporal | LCpl | $2,259.90 |
 | E-4 | Corporal | Cpl | $2,503.50 |
 | E-5 | Sergeant | Sgt | $2,730.30 |
 | E-6 | Staff Sergeant | SSgt | $2,980.50 |
 | E-7 | Gunnery Sergeant | GySgt | $3,3445.80 |
 | E-8 | Master Sergeant | MSgt | $4,957.20 |
 | E-8 | First Sergeant | 1stSgt | $4,957.20 |
 | E-9 | Master Gunnery Sergeant | MGySgt | $6,055.50 |
 | E-9 | Sergeant Major | SgtMaj | $6,055.50 |
 | E-9 | Sergeant Major Of The Marine Corps | SgtMaj | $6,055.50 |
Day in the Life of a 0331 Marine
Machine gunners will spend a large portion of their Marine Corps career at the armory.
Clean and well-maintained weapons are extremely important, so it is not uncommon for 0331 Marines to spend several hours per day at the armory where they will be cleaning and maintaining their weapons.
In addition to armory time, machine gunners will also spend a significant amount of time in the field.
Training is best when it is most realistic, so infantry battalions will find ways to make sure that all 0331s are most prepared for war.
This is done by sending infantry platoons into the field for days or weeks at a time where they will practice “humping” (hiking), deploying weapon systems, and trenching into fighting positions.
Also, machine gunners will work with their platoon to train in MOUT towns and use various tactics to find the best vantage point to engage enemy positions.
MOUT towns are training areas that are designed to represent urban warfare with the creation and maintenance of different building styles.
Since machine gunners are tasked with carrying large amounts of heavy ammo and larger weapons, they tend to be in very good shape.
These Marines are like the oxen of infantry platoons. They will usually be larger and stronger than most of their peers.
This also means that they need to spend more time in the gym, where they will keep themselves in exceptional shape to be ready to deploy at a moment’s notice.
While deployed, 0331 Marines may be tasked with long patrols where they will spend several weeks living outside the wire and doing regular foot patrols.
These Marines will be at risk of encountering enemy positions and will also spend a great deal of time engaging locals as their platoon attempts to locate enemies that may be living within various cities and villages.
Machine gunners may also be asked to stand gate duty with their heavy machine guns or be tasked with going on multiple convoys where they will be responsible for the mounted machine guns, generally the 50-cal or 40 mm.
0331 Reviews
Every Marine has a different experience while deployed, but there is an increased likelihood that machine gunners will encounter enemies or be engaged in firefights while on deployments.
The following two reviews are from Marine infantrymen who had mixed reviews of their time in the Marine Corps.
They both agree that life was busy and that it was hard to be around and see their family.
Civilian Job Opportunities After Serving As A 0331
There isn’t a lot of use for machine gun experts in the civilian world. Even in the police and federal agencies, there are not a lot of heavy machine gun experts.
However, tactics and teamwork are valuable skills that machine gunners can take with them to different agencies if they choose to keep serving.
Knowing how to approach and suppress enemies that are barricaded is very valuable for SWAT teams.
The discipline and determination that it takes to be a machine gunner are valuable skills that Marines can use in other areas of life as well.
Completing college or starting a business are both ventures that Marines have found success in since they are able to tap into their years of discipline and hard work.
If machine gunners are interested in working overseas but want to earn a higher income, there are endless opportunities available for them to work for military contractors.
They will be asked to deploy to remote areas of the world, but the work will be similar to what they were doing in the Marine Corps.
Since there is a lack of work available for machine gunners as civilians, this also means that there are endless opportunities for Marines coming from the 0331 MOS.
They are not stuck doing one job style. If these Marines choose to work hard and use their discipline, then they can create a large number of opportunities for themselves.
Additionally, the Post 9/11 GI Bill is usable in thousands of companies and career opportunities.
It is very easy to use it for apprenticeship programs where Marines can learn a valuable trade while getting paid to learn.
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General FAQ
What does a machine gunner do?
Machine Gunners in the Marine Corps are responsible for the deployment, care, mounting, and unmounting of heavy machine guns.
How much weight does a machine gunner carry?
While the average Marine in the Marine Corps may carry 60 lbs. of gear, machine gunners typically carry anywhere from 70 - 100 lbs. of gear.
How much do machine gunners make?
On average, Machine Gunners can make as little as $1,900 per month, to as much as $2,700 per month.
What types of machine guns do they carry?
Typically, a machine gunner will operate one of the following: M240, 50 Caliber machine gun, and 40 mm heavy machine gun.
