Hrrm, well I tried it again and it seemed to work fine. 
It could be the "use_vs_frigates" that is key there. I am not sure if I had that on the heavier weapons before or not.
I will keep my eyes open for situations where it doesn't seem to work right.
Solved with reservations!
Ahh now I see!
After further exploration I remember now why I don't like that A.I hint.
The A.I for NPC ships will never put a group with that weapon hint on autofire. It seems like a small thing but it has a couple major drawbacks. The first is that if you change your heavier weapons to this A.I hint so they do not waste ammo or flux on fighters, they can only fire one group of weapons at a single target at a time. If you have more than two groups of weapons in this category, one group is almost always just ignored.
So ships with both heavy turrets and heavy hardpoints will never actually fire the hardpoints and the turrets at the same time. Even if the ship has multiple turrets with different arcs, the ship will only ever fire those weapons at a single target instead of the multi-targeting that normal weapons can achieve through the use of autofire.
Also if weapons have slow turning rates, the A.I tends to miss quite a bit since it starts firing manually at a target even if the turrets are not directly pointed at it yet.. as long as at least one weapon can achieve a hit.
I assume the purpose of handling the hint like this is to conserve ammo on the AM blaster, but standard assault and heavy weapons do not cope well with this A.I hint
Soo.. I maintain my suggestion
We really could use an A.I hint that just makes weapons ignore fighters and otherwise act just like a normal weapon. Either that or change the "STRIKE, USE_VS_FRIGATES" hint to use autofire when appropriate. Seems like the first would be easier though.
