I'm no expert, but I assume that the installation 4:12 modact SAS 5.3, does not contain the Mod that has the basic version of the turret so it will not able to load it through the class, my guess is as ignorant on the subject.
Concerning the odd turret behavior. Though the turrets are based on the Wellington's, they are their own class so no other mod is needed for them to work
In the 412 version of the game Team D seems to have change some of the parameters of cockpit functions. In the game, turrets are a cockpit class. It seems to have a affect on most none pilot cockpits and many bomb and gun sights.
Don't worry when 413 comes out I am sure they will come up with something else to complicate modding.
For those who do have a turret that works but has the floating above perspective, are you using some kind of increase cockpit view mod? You can open up the turrets him file, find this entry:
[root]
Mesh root
Parent _ROOT_
Attaching 1 0 0 0 1 0 0 0 1 -1.65131 0.00057
0.85 and lower the number I made bold to something like this till it works for you:
[root]
Mesh root
Parent _ROOT_
Attaching 1 0 0 0 1 0 0 0 1 -1.65131 0.00057
-0.01I have none of the above issues, though I still use the trouble free 409 with ModAct.