If you look at the Kol battleship you'll see you can make "pseudoturrets", though they aren't actually apart of the Kol mesh. Rather they are particles generated by the weapon fire effects. You'll have to ask someone more skilled with the particle forge than me for details, but that's the only way that might work to get naval battleship looking guns to look right.

There are no arcs in SoaSE, only directions (left,right,forward,behind).

Well, there are arcs in Soase... -+90 degrees from the directions... and direction is not related to the visual but to the invisible hardpoint assign to the weapons...

Well, my example was for pop-up turret like these from the Andromeda Ascendant ( http://images.wikia.com/andromeda/images/e/e0/Andromedapdlturretmoving.gif )...

Method in this case is simple... turret is not on the main mesh, only the hardpoint for the particle effect... firing particle effect use the turret mesh... and since particle effect is always tracking the target ( in the limit of the default sins arcs ), problem is solved...

For Gilly6666 case, it will be more complex... basic model need to be without turret with hardpoint for particle... permanent particle effect will be used for generate the turret ( like the rotating section of some ship in the B5 mod )... these method have a little problem... when the ship is build in the shipyard, turret will not be visible... only after launch, the particle effect kick in and turret appear...

For the attack mode, it is similar to the way used in the first example... turret is part of the firing particle effect... problem is that you will have 2 turret, one in rest position and one in tracking position... i am not sure that it will be possible to "kill" the first particle effect in combat mode and restore it once the attack mode is done... well, a lot of think is possible in sins but there is not simple way to make it... and you are limited with the actual sins shader code ( FX files )... until now, it is not possible to add your own shader code...

As today, only moving part ( rotating ), moving texture, visual stealth ( almost transparent ship ) and light emitting texture ( real light via shader, not the fake light via da map ) have been tested... not sure if it will work today, but i have somewhere the first mod made for sins, from the beta version who allow ship to shoot missile who attack them... the same mod ( from before sins was released ) was already having mine ( who have appear only in Entrenchment )... point is Soase have a good engine and that the genius of some coder allow incredible thing... unfortunaly, i am only a modeler and not a coder... a lot of the effect that i was able to make was based on somebody other code, code who don't work anymore in newer sins version since my codding knowledge don't allow me to upgrade the code to the actual version...

Anyway, i think that it can be made... you will need some good modeler, some people who master the particle effect and coders who are able to "think outside the box"... in fact, you will need a full mod team !!!

For the firing arc, 45 degree is not possible, it is hardcoded to +-90 degrees... for big gun oriented to the front, it will not be a problem but if you have smaller gun, like these on the side of WWII ship who are partially embedded in the structure, it is possible that the gun will shoot trough the structure...