Is it possible - i.e. would you allow it as GM - to strip the computer from an AX-108 Ground Buzzer and use it to control a larger weapon system - like a turret on a frighter.
Nearly all characters we have used so far have none or a very little gunnery skill as they are mostely light armed smugglers, bounty hunters or non-combat-classes, so the boost in Gunnery Skill would make a major difference in space combat.

I would per weapon, sure.

Ok... Just read the description of the AX-108 again... It has no gunnery skill but counts as a heavy weapon - so therefore the idea is not so logical any more...

I wouldn't have an issue if PCs wanted a Gunnery version.

And leads to interesting complications if the droid catches sight of something it thinks is a valid target... And just blasts a poor civilian ship into space dust when it came too close.

I would just use a modified Advanced Targeting Array. If I remember right it will add 1 or 2 levels of True Aim, which gives the effect of Gunnery. Otherwise, pay the extra experience for a rank of Gunnery. Too many people focus on whether a skill is a "class skill". It just costs 5 XP extra per level. If you only need 1 or 2 levels, that works well, especially if you already have 4 Agility, which I would assume your smuggler group does. Skills are not the end-all be-all that they are in other games. The end-all be-all is the talents which boost the skills.

Is it possible - i.e. would you allow it as GM - to strip the computer from an AX-108 Ground Buzzer and use it to control a larger weapon system - like a turret on a frighter.

Nearly all characters we have used so far have none or a very little gunnery skill as they are mostely light armed smugglers, bounty hunters or non-combat-classes, so the boost in Gunnery Skill would make a major difference in space combat.

Get an Advanced Targeting Array instead. That can offer you up to three total upgrades to your dice, plus a boost. You still need someone to provide the raw attributes to combine with the skill, but that combo really does help.

We used it last night, and together our Gozanti with one good Gunner (me), plus several guys who had two or three Agility scores, managed to take out a Vigil-class Corvette and his flight of eight TIE fighters.

All those upgrades really do make a difference.

Stay on Target's slave circuit attachment has a mod that makes the ship use its weapons autonomously. That might qualify.

You could also just buy some droids with the appropriate abilities and skills, slap their butts in those seats, and call it done.

In the event it's the only thing available then yes, for a hard mechanics with 2 upgrades (it really would suck if it didn't work properly) check I would let them do it.

If they where going shopping for parts though, then droids and an Advanced Targeting Array is definitely the way to go.