this very well could be because i only have the 'light turret', so maybe the other turrets actually work and start shooting at their targets in a reasonable amount of time.
so im playing a match and i set up a turret to the left of this hallway. a enemy player runs thru said choke point and i proceed to dance around the turret for literally 40 seconds, hoping my turret would wake the **** up and DO SOMETHING, but it didnt. it would seem you have to be standing literally RIGHT IN FRONT of the turret for it to track targets.
to test this theory, i found an enemy turret on the floor. i then stood in front of said turret for what seemed to be several seconds before the turret started firing at me, after which i simply moved behind it and circled around it using my melee to destroy it because it cant turn faster than you can move around it.
call me crazy, but i really think turrets need a MAJOR buff in the time it takes for them to acquire targets then shoot at them (how about 1 second, not 3..). they are literally basically USELESS in this game (keep in mind i have only used the light turret, so correct me if im wrong here).