I guess different fire groups is the answer. Kind of annoying though, you'd thing you could have the ability to stop firing just as easy as you start. You pull the trigger to start firing, don't have to hold it down, so why doesn't another pull stop the guns firing?
On another note, any Anaconda pilots, what do you use on the 2 hard points underneath? I've got a huge MC but I don't know about the other one yet. It seems like it's in a really useless place.
What others wrote about switching fire groups. Assuming you want to halt fire due to the target launching chaff, the moment you switch fire groups (with no turret(s) in alternate group), they stop firing.
Quickly switch back to enable them again with next trigger pull; better yet, use a fixed weapon in the switched-to fire group and fire those until chaff dissipates, and then switch back. I like this better than a second trigger pull.
I haven't seen where changing fire groups unlocks the target; it just stops the turret fire. Seems the feds or other friendlies are always crossing my line of fire; toggling fire groups stops turrets for that moment I want them to stop, and then re-engage with a pull.
Both hardpoints under the conda are great, especially for fixed weapons (no conversion issues). I use a C4 and C3 PA on same trigger (both with long range mod) for alpha damage. The conda is the only ship on which I use turrets, due to slower turn rate. Turrets on top and sides and fixed on the belly is working well for me, but I'm a new conda driver so experience is limited.
One final note: limiting fire groups to two creates a simple toggle for the deactivating/reactivating turrets. I use a KWS on the same alt trigger position as PAs and have this as default when scanning targets. This prevents accidentally firing on a target when you meant to KW scan (ask me how I know...)
ETA - From above post: Setting to Forward makes them fixed weapons, assume with the reduced damage. Less useful setting......