Sentry Gun



The Sentry Gun is an unmanned weapon capable of autonomously acquiring and defeating enemy targets. It, as well as the UAV and Predator, is indicative of the increasing role of unmanned technology on the battlefield.

Though all the parts necessary for building a sentry gun are currently available in the real world, no publicly known design is capable of distinguishing between friend or foe, nor are they man-portable. It would also be a challenge to create a design that would meet battlefield hardiness requirements. Currently, CIWS mounted aboard ships are the closest known relative, though some hobbyists have had success with systems designed around paintball guns.

Campaign
An M5 Sentry Gun is featured in Call of Duty: Modern Warfare 2 during the level 'Wolverines!'. It is positioned on top Nate's restaurant, where it provides autonomous cover for Sergeant Foley and his team during the recovery of codename "Raptor". Ramirez (the player character) can reposition the sentry gun as needed. An enemy sentry gun is seen in Exodus. Parts of the sentrygun can be found throughout makarov's safehouse in the level Loose Ends.

Special Ops
Sentry guns are available for use in Homeland Security, Wardriving and Wreckage. They are especially useful in Homeland Security in helping defend your position, though they'll need to be well protected in order to last through the waves of enemies.

Multiplayer
 is a multiplayer killstreak reward in Call of Duty: Modern Warfare 2. After achieving a killstreak of 5 (4 with Hardline perk), a player may call in a helicopter that will airdrop a package (similar to the Care Package killstreak) containing the sentry gun. After acquiring the package, the player places the gun in the location of his choice. It can detect enemies at a moderate distance, with its cone of fire centered on where its user positions it. The turret can be picked up and moved; the turret is disabled while held, and the player is unable to use weapons or other equipment. Also, the turret will expire after 90 seconds, appearing to short-circuit itself and disappearing off the map.

Any players with the Cold-Blooded perk will not be targeted by the turret (though they are still vulnerable to shots fired at other targets). The sentry gun can be disabled with a single melee hit or by gunfire. It can also be avoided by moving around its flank, outside of its firing arc. A riot shield user can approach the sentry gun and knock it down with the shield bump, or let the gun destroy itself with ricochet hits. If not destroyed, a sentry gun will eventually power down after a period of time. A certain number of destroyed sentry guns will remain on the map and will only vanish when more sentry guns are placed. These destroyed guns form a visual distraction, both because players will approach them cautiously as it's hard to tell if a gun is active or disabled and because they are so bulky, allowing players to hide behind them. They can, however, be fired and walked through.

In objective-based games such as Capture the Flag or Sabotage, the Sentry gun can provide invaluable support while protecting a flag or bombsite. Even on Hardcore, the gun can absorb a decent amount of gunfire before being destroyed. However, it can be destroyed by indirect fire through predator missiles or other aerial support weapons.

Sentry Guns can be beneficial for snipers for numerous reasons. First, Snipers can only have one claymore (Without Scavenger, or One Man Army) to cover them while they snipe. Sentry Guns can provide cover for the sniper rather than a claymore meaning the player does not have to sacrifice a Frag grenade, Throwing Knife, etc for a claymore. Also, unlike claymores where the enemy can come in really close, sentry guns can keep enemies pinned down at a distance and thus, not allowing the enemy to get in close enough to shoot you at an angle or throw a grenade at you.

Tactics

 * It is best that you place a sentry gun with its weak back-side against a wall so that it can't be flanked.
 * Semtex grenades seem to be very effective at neutralizing Sentry Guns. It only takes one well-aimed Semtex grenade to disable it.
 * Having Cold-Blooded will allow you to approach the sentry without it shooting you. However, the sentry gun will still fire upon an ally behind you that does not have the Cold-Blooded perk, hurting you in the process.
 * Bring the Sentry gun behind windows or on high places to allow it to blast opponents without exposing its base to weapon fire.
 * When sniping, using Sentry gun to defend your backside and the entrances and claymores will make your campsite fairly safe.
 * The sentry gun will fire through smoke. Using a smoke grenade to "hide" the sentry can be effective, as opponents may not see the sentry before it is too late.
 * You can go in front of a Sentry Gun with a Riot Shield. This will give you a high amount of experience.
 * A sentry gun can be concealed by plants and other objects, most notably in Favela and Karachi
 * The Sentry Gun can be destroyed by a single melee attack from either a Knife, or Riot Shield. This is not particularly realistic, as you can imagine what it would feel like to slash a solid metal object, but you probably just cut the power or remove whatever it uses to see.
 * Place the sentry on higher ground as it shoots down better than it shoots up. (confirmed)
 * On Skidrow, if your team has control of the stairs to the center hallway, you can deploy your sentry gun to kill enemies all the way to the other side of the hall, while concealing 75% of itself from return fire.
 * Sentry Guns can also be used as bait. Many players, especially on hardcore, will be using Cold-Blooded and attempt to knife the gun from behind. This can be used to eliminate any players that attempt to do so by keeping an eye on your gun.
 * If, on Highrise you place a Sentry on the roof of the southern building, or, less effectively, the second floor of the northern building, the gun can achieve long-range cross-map kills, and the guns are very hard to destroy.

Trivia

 * The original sentry gun concept art used a XM312 machine gun instead of a M134 minigun.
 * It is possible to read the writing on the ammo box of a Sentry Gun in the Museum. The writing says 600 Cartridges// 7.62 IW Sentry // Infinity = M1920, followed by a serial number.  The IW and Infinity is most likely an Easter Egg referring to Infinity Ward.  It could also refer to how the Sentry Gun technically has infinite ammo.
 * An EMP can disable the Sentry Gun.
 * A Sentry Gun can acquire and destroy helicopters and Harriers. It can even acquire an AC130, but cannot destroy it.
 * The Sentry Gun has a Picatinny rail attached to it. However, no upgrades are actually available for the gun.
 * Oddly in the single player level Wolverines you can move the Sentry Gun out of Nate's to the other restaurants
 * The Sentry Gun has a 90 degree angle within which it can engage targets
 * Much like the Pavelow, only the first Sentry Gun to be called in adds to your killstreaks, and only during its initial deployment; if moved, kills will no longer count. Any other Sentry Guns called in the same game, by any team, will not add to killstreaks.
 * There is a limit of 32 Sentry Guns on a map before the game crashes.