HECU Sentry Gun

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{{Weapon Infobox
| image=FileHECU Sentry.jpg|220px
| image2=
| name=HECU Sentry Gun
| affiliation=*Hazardous Environment Combat Unit
*Black Ops
| manufacturer=
| model=
| type=Autonomous gun platform
| damage=3 (Per bullet)
| magazine=
| magtype=
| maxammo=Infinite
| fire=
| ammotype=
| operation=
| rate of fire=High
| recoil=
| spread=
| projectile speed=
| accuracy=
| range=
| maker=
| usedby=
| counterpart=
| counterwep=
| entity=monster_sentry
| designer=
| hidep=
| hidet=Yes
| hideu=Yes
| hideg=
}}
The '''Hazardous Environment Combat Unit Sentry Gun''', commonly referred to as the '''HECU Sentry Gun''', is a fully autonomous weapon featured in ''Half-Life'' and its expansions. Sentry Guns are commonly used by the Hazardous Environment Combat Unit|HECU and Black Ops to guard WikipediaChoke point|chokepoints and vital areas, and share many aspects of their design with the Combine Sentry Gun|newer model seen in the sequel, ''Half-Life 2'', including a tripod base and a tall, narrow body.

==Overview==
The gun consists of a powerful machine gun built onto a tripod. The gun itself rests on a turntable mechanism of sorts on the top of the tripod, which allows it to rotate and fire in any direction, unlike the equivalent device in ''Half-Life 2'', which has a narrow field of fire.

Gordon Freeman encounters a Sentry Gun for the first time in the chapter ''"We've Got Hostiles"''. These were used by the HECU to guard areas after their soldiery had passed through. Some gun relies upon an independent laser sensor to detect targets, some may deploy automatically without laser. Once a target has tripped the beam or has been detected automatically, touching a sentry, firing near a sentry (GoldSrc only) or damaging it, the turret deploys its weapon with a high pitched whine, and fires upon any target in sight. Once activated, the sentry would remain alert for a time (it makes a steady beeping sound whilst scanning for targets) before sinking into a dormant but alert state. Despite appearing gawky and unstable, these guns are in fact stronger than they appear, and are difficult to knock over. Enough of any type of damage will knock them over, but explosives are the most effective counter.

A variant is encountered later on that auto-arms when it detects motion. The PlayStation 2 port put a red light on these to indicate that they were motion-activated rather than sensor-activated.

==Tactics==
Sentry Guns are powerful enemies, but are severely limited in mobility. When encountering one, stepping back and considering tactics is advised, as unlike other enemies, this one does not move. Looking for a way around or using explosives is a good move.

Since ''Half-Life'''s GoldSrc engine lacks a robust physics system, Sentry Guns simply fall over once they've taken a set amount of damage. Sentry Guns can take a considerable amount of damage, so opt for hard-hitting attacks, like a well-placed Colt Python shot, a HECU SPAS-12|Shotgun double-blast, or explosives, like Mk 2 Grenade|Grenades, Satchel Charges, or the HECU RPG|RPG. Also, keep an eye out for their laser sensors; avoid tripping them, bypassing fighting the guns entirely. However, these tactics may change when playing ''Half-Life Source'' because of the upgraded physics engine although like their GoldSrc brothers they "die" when they take enough damage.

==Trivia==
Unlike the Black Mesa Ceiling Turret|Black Mesa counterpart, these Sentry Guns do not go into standby mode and retract into its body if there are no targets in range. The only way to disable the turret is use explosives or gunfire, as they do not have switches to deactivate them. However, in ''Half-Life Source'', it possible to disable these turrets by using console command "ent_fire monster_sentry deactivate".

==Gallery==

FileHECU Sentry Decay.jpg|''Decay'' model.


==List of appearances==
*''Half-Life Day One'' {{1st}}
*''Half-Life''
*''Half-Life Opposing Force''
*''Half-Life Blue Shift''
*''Half-Life Decay''

{{Weapons}}
{{HECU}}
{{Black Ops}}
CategoryHalf-Life
CategoryHECU weapons
CategoryBlack Ops weapons
CategoryWeapons
CategorySentry weapons