Actually, they're suped up super-anti-fighter/anti-capship hybrids. (so sue me, I'm just starting to edit .tbls!)
They're really a copied version of the AAAf with a new name. They also have the "huge" tag on them. I took that out, and it still shoots three an once (making that ship a ***** to attack... over 60 guns each firing 3 AAAs each... ouch!).
Why don't you try this yourself; go to the ships.tbl, copy a ship, give it a new name, and add "AAAf" "AAAf" "Shivan Super Laser" for each for the turrets. See what happens.
I'll have to try reducing the number of weapons on a turret to one later.