They are employed by technologically advanced organizations, such as the Enclave, or the Brotherhood of Steel, and historic sites for security detail, such as the Museum of History, though in the latter case their former operators had been long since dead. In one case, a raider gang near the Arlington Library has reprogrammed turrets to protect their camp and chem lab.
Automated turrets can either be mounted to the ceiling or the floor. Those mounted on the ceiling fire conventional ammunition at an automatic rate, whereas floor mounted turrets fire laser beams similar to the laser rifle but in a faster succession. Both varieties have unlimited ammunition. As a rule, odd numbered turrets use conventional bullets and even numbered turrets use laser projectiles.
Automated turrets are often found in military installations or areas of historical value. Although not too damaging at lower levels, they can be quite deadly if they surprise you, or if they are in groups. Both types of turrets can be frenzied by shooting either the targeting chip (on ground units) or the lens (on ceiling units). Once frenzied, similar to insects or robots, the turrets will fire on everything they see.
In contrast to automated turrets, alien turrets are only ceiling-mounted. They shoot energy beams similar to the alien atomizer and disintegrator but in more rapid succession. The individual pulses aren't highly damaging, but can take a chunk out of the player's health if they get caught out in the open for too long. Fortunately they are weak in defense and even the higher level turrets have relatively low health.
While they cannot be shut down or frenzied via terminal, it is possible to remotely detonate them using nearby switches aboard the Mothership. They explode in a blast of green plasma, similar to a plasma grenade. They are unable to shoot directly below them, so if you wish to avoid them, stand directly underneath them.
These can be found on buildings, bridges and ceilings. A couple are found at Fort Independence. These turrets are often used by organizations such as the Brotherhood Outcasts, but can be found widely across the wasteland. Even raiders use them as sentries. They can be frenzied just like any other turret when the player targets the lens.
These turrets can be found inside, and in front of, buildings, as well as on bridges. All floor-mounted models have laser weaponry and can be frenzied when their targeting chip is destroyed. Some can be found at the Citadel.
These turrets are found on the Chinese compound wall during the final quest in the add-on: Operation: Anchorage. As expected at this stage, these turrets have much higher Hit Points than than the Mark I bunker turrets.
Turrets are generally controlled from a nearby terminal. Using your science skill to hack the terminal will allow you to override the targeting parameters, which will allow you to either reset its targeting parameters, causing it to target any character (not just the player, similar to the frenzy effect), or shut it down completely. After being turned off the turret can be turned back on at the same terminal if so desired.
The ceiling-based turrets have a blind spot directly below them.
With the Robotics Expert perk it is possible to sneak up on turrets and disable them. You don't necessarily need to be [HIDDEN], simply being momentarily out of sight is enough to deactivate them.
Turrets, like eyebots, cannot be looted for scrap metal when killed, as they either explode into small pieces, or disappear altogether. However, sometimes floor-mounted turrets will not explode, yielding some scrap metal.