Sentry bot ( Fallout : New Vegas ) Sentry bots are found in the Mojave Wasteland , Big MT and the Divide in 2281 . Background . Its successor ( manufactured only in limited amounts ) is the bipedal Mark II sentry bot . Characteristics . Specifications . Similar to their " Fallout 3 " counterparts , sentry bots found in the Mojave have two arms that end with deadly weapons ( a minigun or Gatling laser on the right arm , and a missile launcher on the left arm ) , and tripod legs with wheels . They also have armored heads and , as such , receive less damage from head shots . They are programmed with an authoritative , professional military personality , in contrast to the " gung - ho , " patriotic personality of the Mister Gutsy models . Gameplay attributes . Because of their high health and destructive weapons , sentry bots are formidable combatants and can be difficult to put down , especially fighting them at a low level . Like all robots , sentry bots have a combat inhibitor on the back of their chassis that , when destroyed , will cause the sentry bot to go berserk and attack everything near it . Being a robot , sentry bots have no defense against electromagnetic pulses ( EMP ) , so they can be heavily damaged by , , or any other weapon that produces an EMP . The sentry bots ' use of their weapons systems depends on the distance to the target . If the target is at a long range , they ' ll rely on the missile launcher to damage the target while also using their secondary weapon ( Gatling Laser or Minigun attachment ) . However , once the target reaches mid to close range , sentry bots rely primarily on their minigun / Gatling laser attachments instead of their missile launchers , possibly to avoid splash damage . Variants . Sentry bot . Sentry bots are armed with an arm - mounted or on the right arm , and a on the left arm . They have thick armor plating , and are agile in combat . Although not as common as in " Fallout 3 " , they can still be found in various parts of the Mojave Wasteland that contain robotic guardians , such as the sacrificial chamber in Vault 11 ( depending on the Courier ' s level ) or the securitron vault . REPCONN sentry bot . Twelve of these particular type of sentry bot can be encountered at REPCONN headquarters , and only here . They have the same paint scheme as standard sentry bots , but with " REPCONN " emblazoned in white across their chest . They are also much shorter in height and have glowing green eyes instead of red . If the player trips the alarm system , these bots will emerge from the hidden rooms inside the building . Hardened sentry bot . A hardened sentry bot is a tougher version of the military sentry bot . They are encountered along with around the crashed vertibird in the Mojave Wasteland . Hardened sentry bots have nearly twice as much health as a standard sentry bot ( 500 hit points as opposed to 300 hit points ) . However ( possibly due to a developer oversight ) , despite what the name might suggest , they are completely unarmored with a DT of 0 , unlike a standard sentry bot which has an innate DT of 18 , and thus can actually survive less damage than a standard model sentry bot . One result of their increased raw health is a greater resistance to s . This conforms with the actual electrotechnical definition of the term " hardened , " meaning that hardened electronics are much more resistant to electromagnetic pulses . NCR sentry bot . It is similar to the military sentry bot in appearance , but is differently colored , with orange eyes instead of the standard red . The NCR sentry bot was originally intended to be stationed in Camp McCarran , evident in its G . E . C . K . id McCarranFieldSentryBot , but was cut from the final version of " " . Mark series ( " Old World Blues " ) . The sentry bot mark series appears only in the " Fallout : New Vegas " add - on " Old World Blues " . The multiple different variations range from being significantly weaker than regular sentry bots to being significantly tougher than the base variant . Prototype sentry bot . A world object on display in REPCONN headquarters . Appearances . Sentry bots appear in " " and its " Old World Blues " and " Lonesome Road " . Bugs . If a sentry bot is firing for an extended amount of time , the sound may glitch and keep repeating ( notably the Gatling laser variant ) .