It should reset once the target dies because it will have to re-acquire new targets for the weapon. But as long as the original target ship remains alive, the weapons only fire at that single ship indefinitely.

I have seen this with a TEC Starbase i build. The AI was exploiting it very nicely, sending in devestators first, then the rest of the fleet.

I am sure it was a random occurance, but at that moment i thought 'man, that AI is good'.

sending the cap ship in first is a good tactic indeed, never thought of it really.

but you really need the healers... uhm I mean regeneration-ships to back it up or the starbase will blow it to pieces quickly

Just make sure you don't forget to taunt.