I think Gregg might not know that FIST is a term for fire support team. Ranger and even us non-ranger light infantry types generally have mortars (60mm,81mm, and sometimes 4.2inch)as our organic indirect fire weapons. On the other end of the spectrum are the various larger weapons of the artillery. I have done lots of work with mortars, including FO (Forward Observer). He's the guy registering targets, observing the enemy, and calling for fire missions based on the enemy's proximity to those registration points. This is pretty much what you'll be training to do for the artillery. FIST teams often control all the indirect fire and will request a particular weapon based on the target. For example, you'll learn that it will do little real good for you to call in mortars onto enemy armor, it just ticks them off. You'll also be on a first name basis with your FDC (fire direction center) as these are the guys you'll be in constant communication with and they will translate your panicked blabbering into something the gun crews(a strange breed of people) can actually understand.