03 Infantry
03 Infantry is the center of Marine ground combat. The field covers the Marines who close with and destroy the enemy by fire and maneuver, repel attacks by fire and close combat, and carry the burden of small-unit fighting when the mission turns physical and fast.
Occupational Field 03 contains six enlisted MOS codes covering the full range of infantry employment: the core rifleman, vehicle-mounted reconnaissance, special operations-adjacent recon, crew-served direct fire, indirect fire, and anti-armor. Most roles begin in the same SOI training pipeline and diverge at the MOS school level, but the physical and mental standards that open the field are shared across all six specialties.
Marines who thrive in OccFld 03 typically share a few traits regardless of specific MOS: they prefer physical work over desk work, perform under pressure and uncertainty, and are motivated by team outcomes rather than individual visibility. The field rewards physical readiness, tactical discipline, and the ability to execute in conditions that most environments do not replicate.
At a Glance
| MOS | Title | ASVAB Line Score | Training | Clearance | Civilian Equivalent |
|---|---|---|---|---|---|
| 0311 | Rifleman | No line score minimum | ITB, 59 days | None | Law enforcement, security |
| 0313 | Light Armored Reconnaissance Marine | CL 90 or GT 90 | ITB + LAV crewman school | None | Fleet management, vehicle operations |
| 0321 | Reconnaissance Marine | CL 105 or GT 105 | ITB + BRC (~12 weeks) | Secret | Intelligence collection, federal law enforcement |
| 0331 | Machine Gunner | EL 90, GT 90, or MM 90 | ITB, 59 days | None | Weapons maintenance, security |
| 0341 | Mortarman | CL 90 or GT 90 | ITB, 59 days | None | Fire coordination, precision logistics |
| 0352 | Antitank Missile Gunner | GT 95 or MM 95 | ITB + anti-tank missile course | None | Missile systems technician |
Which Role Fits You?
Choose 0311 Rifleman if you want the foundational infantry experience. The rifle platoon is where the Marine Corps builds the standard. 0311 is the highest-volume infantry MOS and the most common entry point into OccFld 03. No standalone line score minimum means the entry gate is primarily physical and contract-based, not test-driven.
Choose 0321 Reconnaissance Marine if you want the most demanding version of infantry work. Recon requires a Secret clearance, a multi-week Basic Reconnaissance Course beyond ITB, and a competitive selection process. The payoff is work at the intersection of intelligence collection and direct-action operations. CL 105 or GT 105 is the published ASVAB threshold, one of the highest in the infantry field.
Choose 0313 Light Armored Reconnaissance Marine if you want combined-arms work with a vehicle systems layer. LAR Marines operate as part of LAV-25 crews, adding a maintenance and gunnery burden on top of standard infantry duties. The crew role and vehicle-specific training distinguish this path from the rifle platoon track.
For crew-served weapons paths, the choice between 0331, 0341, and 0352 breaks down by weapon system and role in the fight:
- Choose 0331 Machine Gunner if you want sustained direct fire. The M240B and M2 define the platoon’s suppression capability.
- Choose 0341 Mortarman if you want indirect fire and calculation-intensive work. CL 90 or GT 90 reflects the verbal and computational demands.
- Choose 0352 Antitank Missile Gunner if you want anti-armor targeting. The Javelin’s fire-and-forget capability and ITAS optics add a technical layer not found in other infantry specialties. GT 95 or MM 95 is the highest line score threshold in the field.
All crew-served paths share the same ITB baseline. The comparison table above shows specific line score and clearance requirements for each.
Common Entry Requirements
All OccFld 03 Marines enlist with a minimum AFQT of 31, a high school diploma, U.S. citizenship, and MEPS medical clearance. Boot Camp is the first training gate: 13 weeks at MCRD San Diego or Parris Island. After graduation, infantry-track Marines attend the School of Infantry at SOI-East (Camp Lejeune) or SOI-West (Camp Pendleton) for the Infantry Training Battalion pipeline before their MOS school. There are no field-wide waiver programs or alternative entry paths for this occupational field. See each role’s profile below for specific ASVAB line scores, training details, and additional requirements.
Career Field Directory
Rifle and Maneuver
- 0311 Rifleman : frontline infantry, the core rifle MOS and the highest-volume entry point into OccFld 03
- 0313 Light Armored Reconnaissance Marine : vehicle-mounted combined arms on the LAV-25, with crew gunnery and maintenance duties alongside infantry tasks
- 0321 Reconnaissance Marine : special reconnaissance with a Secret clearance requirement and a competitive multi-week screening process beyond ITB
Crew-Served Weapons
- 0331 Machine Gunner : sustained direct fire using the M240B and M2; the rifle company’s primary suppression asset
- 0341 Mortarman : indirect fire employment using 60mm and 81mm mortar systems, with ballistic computation and fire support coordination
- 0352 Antitank Missile Gunner : Javelin and ITAS targeting for armored-threat engagement at extended ranges
Related Resources
Explore all enlisted career paths at enlisted careers. If you are planning for an infantry enlistment, the ASVAB guide and PiCAT guide cover the testing baseline and score planning before recruiter contact. For the full enlistment process, How to Enlist in the Marine Corps covers the steps from recruiter visit to contract signing.