Sentry Gun



"Sentry Gun on the way!"

— Multiplayer announcer when friendlies call in Sentry guns

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 sentry gun can be found throughout Makarov's safehouse in the level Loose Ends. It can also be found during the level Endgame on one of the banks during the boat chase before you go through the cave.

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
The  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. If not destroyed, the turret will expire after 90 seconds, appearing to short-circuit itself.

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. A flashbang or stun grenade disables the Sentry Gun for a few seconds, leaving it vulnerable to knife. 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. 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.
 * Place your sentry guns to guard a high priority objective like a flag or bomb site, that way there are fewer players needed to defend such objectives.
 * 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.
 * Place the sentry on higher ground as it shoots down better than it shoots up.
 * 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.
 * There is a tip shown when the game loads a multiplayer map that alleges that Sentry Guns can be temporarily disabled by throwing a flashbang or stun grenade at it. (confirmed)
 * A sentry gun does not self-destruct after being set up, if it remains undisturbed. However its health gets less and less so a flash could disable it.
 * Place a Claymore behind your sentry gun, facing in the opposite direction (back to back) so that knifers may get killed if they try to slash the sentry.
 * Placing a sentry gun on top of a destroyed car gives it a much better kill zone (confirmed on wreckage) although the car must be destroyed prior to placement otherwise it will destroy the sentry gun when it explodes.
 * Place a sentry gun on a high area because it will act like an anti-aircraft gun and attempt to shoot down killstreaks.
 * Another good tactic is to use a harrier strike and a sentry gun because they both attempt to shoot gown killstreaks while you do nothing.

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 180 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. Any other Sentry Guns called in the same game, by any team, will not add to killstreaks.
 * There is a limit of 32 total Sentry Guns on a map.
 * If a player is killed while holding a Sentry Gun, it will drop to the ground and deploy where they died and facing in the direction it was held. However, this only applies if the Sentry Gun was in a position where it could've been deployed, otherwise it goes back into your inventory.
 * As to the above, a Sentry Gun that has been played, then picked up by the player, and the player is killed the Sentry Gun will dissapear if it was not able to be placed.
 * The Sentry Gun cannot be destroyed with single Throwing Knife throw.
 * A useful tactic is place the Sentry Gun in a humvee's gunner position in maps like Afghan. They become hard to spot and are frequently passed by.
 * If a player is playing spec ops and is killed while holding the sentry gun they will still be carrying it while they are down. Enemies will shoot at it providing great cannon fodder for the other player.