I'm not sure if this is a bug or feature but we can't seem to use the rail speed controller on the rail turret axis.
No if we could this would help those that want fixed direction turrets but don't want to put up with the issue of the AI going back into ship mode and not shooting if on a normal rail. Also it'd help removing the need of having to use unending collisions to keep it in place if using rail turret axis blocks.
Being able to use the Speed controller on the axis would end...
Enable Use of the Rail Speed Controller on the Rail Turret Axis?

Being able to use the Speed controller on the axis would end...
Enable Use of the Rail Speed Controller on the Rail Turret Axis?