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1.
An 0331 is Marine machine gunner. the dumbass above failed to mention that its not just a SAW they carry. They also employ the M240B, M2 .50 cal, and the MK-19 40mm machine gun. They are the most badass muthafuckas to walk this earth and are the backbone of Marine Infantry units.
0331's are the badasses of America's most badass fighting force
by johnnycash1234 July 02, 2010
 
2.
A Grunt in the US Marines who carries a SAW (Squad Automatic Weapon) AKA Machine Gun

The worst job in the whole goddamn military. You run around an go on long humps (HIKES) in full gear an you also have to lug around a machine gun that takes forever to clean an almost never works when you need it, because the Marine Corp cant provide proper lubrication for your weapon so it does nothing but jam.

Of Course Everybody in your squad who isnt an 0331 wants to use your machine gun, an make videos of it. but they dont wanna clean it.
Jose: "So whats your MOS in the Marines dude."

Brando: "Im an 0331, Im a machine gunner."

Jose: "THATS SO COOOL DUDE!!!"

Brando: "NAW!! Its horrible. It takes 5 hours to clean an every round I shoot equal 2 hours of police calling!"
by llegoz October 16, 2009