US Marine MOS List: Guide to Military Specialty Codes The United States Marine Corps (USMC) offers a wide range of career opportunities, each with its own Military Occupational Specialty (MOS) code. These MOS codes are used to classify and categorize the various job roles within the Marine Corps. This guide will provide you with a comprehensive list of the US Marine MOS codes, along with a brief description of each specialty. 1. Infantry (03XX MOS) The Infantry is the backbone of the Marine Corps, responsible for engaging in ground combat and capturing enemy positions. The 03XX MOS includes several sub-specialties, such as: 0311 – Rifleman 0331 – Machine Gunner 0341…