|Army Enlisted Job Descriptions & Qualifications|
|13X - Field Artillery Enlistment Option|
13X isn't actually an MOS (Military Occupation Speciality). Instead, it's an enlistment option. The "X" means that the specific job is not known at the time of enlistment.
Individuals who enlist under the 13X Infantry option attend Field Artillery OSUT (One Station Unit Training), which combines Army Basic Training and Field Artillery AIT (Advanced Individual Training), all in one course. During that training, recruits are allowed to list their specific Artillery job preferences, but ultimate assignments are determined by the "needs of the Army." Upon graduation from OSUT, recruits are assigned to one of the following Field Artillery MOS's: