The XM-88 Archer Anti-Personnel Turret is an automated turret gun composed of a rotary cannon. It fires 7 gram depleted uranium saboted slugs at a high rate of fire.
Many of these turrets are seen destroyed throughout Area 51. Only a couple are active, however. In Doctor Cray's lab, there are three active turrets guarding the entrance, with two more just outside of the entrance, which are destroyed. Some are under control of the Illuminati.