The first part of mine is pretty simple USMC - United States Marine Corps. I served with 3rd Battalion, 7th Marines from 1990-1996...I was a Sergeant when I was honorably discharged.
0341 is an "M.O.S." - miltary occupational specialty. The first 2 numbers are the occupational field - "03" is infantry and combat arms. The second numbers "41" refer to a specific discipline or weapon system in the "03" field - in my case, mortars.
For you military buffs, here's the breakdown of the "03" field, if you care to know:
0311 - Rifleman
0313 - Light Armored Vehicle Crewman
0331 - Machinegunner
0341 - Mortarman
0351 - Assaultman
0352 - Antitank Assault Guided Missileman
0369 - Infantry Unit Leader
There is one exception to the numbering scheme:
8541 - Scout Sniper
One other note - all Marines, especially in the infantry - are riflemen first, and we all carry one, regardless of our M.O.S. Our weapon systems are specialties, but we all have to master the service rifle and qualify every year (6th award expert rifle and pistol I might add...I had to throw that in).
OK - So now that I have bored the living shit out of everyone and been WAY to detailed in my reply - that's how I got my screen name...
JB