I was hoping Ian wouldn't eat up ammo like the companions in later games, but a Google search put that hope down.
Anyways, me and Ian just cleared out the radscorpion cave for the people of Shady Sands. I could only fire one shot before running out of AP, so mostly it was Ian who did all the work. They say he always misses and hits the player instead, but he only shot me once.
So is keeping up his ammo supply a major concern and a top priority or should I just neglect it until I find a merchant?