Not really. AI are, by design, only meant to last for a single encounter. In that single encounter, one of the following occurs:
- The NPC dies
- You die
- The NPC runs
- You run
Once any one of those things happens, you will never see that exact same AI instance* ever again, so how much ammo they have/had is kind of irrelevant. Now, if an AI instance* were to start living across encounters, then ammo limits would need to be addressed.
31 shots from a Railgun/PA
should last longer than the lifespan of an AI instance (not to meantion 105/1500 for the cannons/multis), and only in the rarest of occasions will it not. Therefore ammo usage (and the code to deal with "running out") is one less thing to worry about in the AI code.
(* - note I'm using the word "instance" in the programming sense, not the P2P networking sense)