If you are using the turret behaviour. Have you tried using "predictive aim" aswell?
There are other ways. I haven't used turret behaviour myself but if you are a beginner then this is probably the easiest way.
In fact it looks like the behaviour might already do what you want without predictive;
From the manual: "On target acquired is triggered, and if Rotate is set to Yes the object will start rotating towards the target. Once the turret is pointing in the direction of the target, On shoot will trigger at the frequency determined by the Rate of fire property."