There was a thread on this a while back in which I tested AI on all guns. Their behavior has changed since then, it seems. If I recall, they would load heavy in the gat, and charged in three of the large guns every time, all but the Hwatcha. I just retested, and got some odd results.
The AI no longer load Charged in the heavy carro. They shoot standard ammo until the target is further away, then actually switch to heavy (though not always). It was hard to test, but it seems the range they switch is about 150 meters. And they always shoot at the balloon. This sort of makes them better than most new gunners on the carro.
In the Hwatcha, they seem to use Charged or standard at sort of random. If they take the gun from you, they will load in standard every time until they pick their own target during a reload that they started on the seat. Then they will load Charged every time. They never use Heavy.
They used to load Charged in the flak every time, but now use Standard at all ranges.
They only use Standard in the Lumberjack, though I noticed an odd thing. They switch between targeting the balloon and guns of an enemy seemingly at random.
