How does the Sabre turret prioritize targets?

Solution 1:

You are right, it's closest enemy first. Once locked on, it keeps tracking the enemy - doesn't matter how far he is from the turret.

So it goes like this: You launch the turret, it searches for the closest enemy and locks on it. (Even enemies have same AI and they will target the closest player. So if you throw your turret between you and the bad guys, they will target the turret instead of you.) The turret starts shooting the enemy until he/she/it is dead.