They are so easy to destroy that even if you have them in a perfect spot it takes only a second to disable them since they stop working at half health.
Sometimes they scan right over enemies and never even fire. I had some games yesterday where enemies would stand right in front of it and the thing just kept scanning back and forth doing nothing. Finally a guy noticed that it was there and stood still and chucked a grenade at it from 10 feet away. ( they had time to take me out during that time ).
Their range is comical combined with their scanning.. IMO turrets shouldnt have to scan .. There should just be a FOV sensor on them that alerts them to enemies and then they aim. Scanning back and forth is just wasteful.
I have no idea how much damage they do because I have never been hit by a turret yet either.
I have more KILLS with Landmines than I do total HITS by the turret.