This was in one of the campaign scenarios, you are given two AT guns with 4 rounds each plus two ammo bearer teams with a further three each. This is against an indeterminate amount of armour. One of my guns shot off all four rounds at a squad in one turn, I won the battle but it's still annoying to have the AI waste ammo like that.
In general I think the tac AI does a good job, but the rate of fire from some of the units is a bit fast, tanks have this problem too but they generally have enough ammo that its not an issue.
A target armour arc would be perfect, I've never played CMx1 so I didn't know that used to be a thing.