Hm, in earlier versions, the AI tended to skimp on the number of firecons used, so you could swamp it with many small salvos.
Blue Emu (from Paradox Fame) came up with a way to do this.
Say, you have a ROF of 30 seconds.
You assign 1 tube to each FC and open fire.
5 sec later, you assign another tube to the same FC, so another missile is fired.
Important! Leave the already fired tube assigned!
Rinse repeat until the first launcher has reloaded.
Due to the reload time and the intervals, your launchers have fired, your ship will now shoot a missile per FC every 5 seconds.
The launchers to FC ratio should be equal to your ROF / 5
It is a bit of an exploit of the way Aurora works, but in a case like yours I will overlook it