Sentry Gun
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The Sentry Gun (abbreviated to SG), officially known as Sentry Mechanical Firing Device and also known as Sentry or Turret, is a building that can be constructed by the Engineer using the PDA, the Engineer's build tool. The gun itself is a tripodal device constructed of metal, team-colored paint, and a laser sight (when used with the Wrangler).
A level one Sentry Gun is a single-barrel machine gun with an internal magazine. The Sentry has a motion sensor, as stated in Meet the Engineer and the Sentry Manual.
A level two Sentry Gun appears to use an automatic cranking system to rotate the barrel, as indicated by the 2 electric cables visible. It also has 2 Gatling guns and a laser sight is built into the carbine body. Its ammunition is belt-fed.
A level three Sentry Gun is identical to the level two, with the exception of an additional set of rocket silos on the top, which comes out of the back ammunition housing area.
The Sentry Gun functions as an automated turret that fires at the closest enemy within its range and line of sight. Dealing constant as well as consistent damage with noticeable knockback and having an immunity to Critical hits, a Sentry Gun is the cornerstone of a successful defensive setup. On the other hand, they take a while to set up to full potential, and even a fully stocked Sentry Gun can be destroyed with little trouble by a well-executed ÜberCharge or a Spy with his Sapper. Engineers must be on the lookout for such threats to ensure their Sentry Gun's survival. If a Sentry Gun is sapped, it gains a 33% damage resistance against a Spy's weapons.
Contents
Functionality
General
The Sentry Gun costs 130 Metal to build, 200 Metal to upgrade to Level 2, and an additional 200 to upgrade to the third and final level totaling to 530 Metal. With each upgrade level, the Sentry Gun becomes more powerful, gaining machine guns, rockets, as well as more health and a minor damage resistance to all Miniguns. The firing range remains constant regardless of level. The Sentry Gun's ammo and health may be replenished with Metal by the Engineer hitting it with his melee weapon. Each bullet reloaded costs 1 Metal and each rocket reloaded costs 2 Metal.
When placing a Sentry Gun, the Engineer can see the limit of its range represented by a team-colored sphere of 1100 Hammer unit radius. A Sentry Gun that is being constructed has health increase gradually until it reaches its maximum health upon completion. While automatically scanning, the Sentry Gun rotates 90 degrees about the direction it is pointing; however, it is capable of detecting and rotating the full 360 degrees to lock on to a target. This takes a brief moment, however, which may allow faster foes to slip past its range. The Sentry Gun can also be manually rotated when placing to face a different direction before building commences. When the blueprint is shown, using the alt-fire button (default key: MOUSE2) rotates the blueprints counterclockwise by 90 degrees.
Properties
As do other Buildings, Sentry Guns emit sound cues to alert players to their presence and status. A scanning Sentry Gun makes a number of beeps every time it reverses its rotation (1, 2 3) — the number of beeps corresponds to its upgrade level, where a Level 3 turret makes three quick beeps. Additionally, this beeping increases somewhat in volume with Level 2 then Level 3 Sentry Gun's level; so, the higher the level, the farther away the Sentry Gun can be heard; this fact can help attentive players find guarded areas. The Sentry Gun's scanning noise sounds slightly different when being fired on by the enemy; slight clicks can be heard along with the regular beeps. The scanning Sentry Gun also makes a distinctive noise when it detects and locks onto an enemy target just before firing — this noise both alerts the enemy of the detection by the Sentry Gun and the team of the presence of an enemy within the range of the Sentry Gun. Enemies detected by a Sentry Gun hear its noise as a slightly different alert noise. All of these scanning noises are silenced when a Sentry Gun is Wrangled.
A Sentry Gun constantly checks if there is an enemy player or building in scanning range with a clear line of sight. If multiple targets meet this criteria, it selects the closest one and switches targets the instant another target is closer, prioritizing players over buildings in its range. Sentry Guns also only attempt to fire once they have lined up with the target, even if firing before then could cause damage to an enemy. Sentry Guns have a maximum rotation and pitching speed when attempting to track a target, which increases with level and is faster than its idle scanning rotation. Sentry Guns still aim and try to fire at enemies even if their ammo reserves are empty.
Sentry Guns cannot see through geometry and Engineer buildings; however, they ignore friendly players.
After running out of valid targets for whatever reason, the Sentry Gun briefly stays pointing in the direction of its last detected target before returning to its scanning sweeps.
Since the Engineer Update, players are able to haul their buildings around. An Engineer carrying his Sentry Gun moves 10% slower and cannot fire or change weapons. A redeployed Sentry Gun retains its previous level and automatically sets up twice as fast. Engineers do not lose any Ammo or Metal by moving Sentry Guns (unless the Sentry Gun was picked up with the Rescue Ranger's alt-fire, which costs 100 metal for moving any building). If the Engineer is killed while hauling his Sentry Gun, it is automatically destroyed along with him and gives a notification in the kill icon area of the screen. Sentry Guns under the effects of a Sapper cannot be picked up.
Like most other weapons, the Sentry Gun's weapons have damage ramp-up and fall-off. Sentry Gun bullet ramp-up and fall-off is calculated based on the distance between the enemy and the Sentry Gun. However, the rockets from a Level 3 Sentry Gun calculate their ramp-up and fall-off based on the distance between the enemy and the Engineer who built the Sentry Gun.
Unlike most other weapons, the Sentry Gun's weapons do not gain Critical hits. It is possible, however, to make the Sentry Gun deal Mini-Crit attacks and damage if its target is coated in Jarate, being Marked For Death, or if the Engineer who built the Sentry Gun is close to a Soldier with an active Buff Banner – boosting the damage of each bullet to 22.
Sentry Guns are controlled by the TF2 server rather than the Engineer's client. That means Sentry Guns behave the same regardless of the connection quality of the Engineer that built them.
Specific properties
Included in the Engineer Update as an unlockable secondary replacement, the Wrangler allows the Engineer to take direct control of his Sentry Gun by "marking" targets manually. Doing so shuts down the Sentry Gun's automated target-lock system but diverts the excess power from the targeting system into speeding up its firing rate, effectively doubling the damage-per-second of the Sentry Gun. The Wrangler also provides the Sentry Gun with a protective shield which absorbs two-thirds of enemy fire while the Wrangler is active. A wrangled Sentry Gun has no maximum range, though its accuracy slightly decreases at longer ranges and its knockback force is halved against targets outside of its normal reach. Once the Engineer switches away from the Wrangler, however, his Sentry Gun is unable to fire for 3 seconds while its auto-lock targeting computer reboots. It is still shielded during this time.
In Mann vs. Machine, Sentry Guns can gain benefits from certain Power Up Canteens. An ÜberCharge Canteen forms a Wrangler-esque shield around the Sentry Gun, reducing incoming damage by 90%. Use of a Kritz Canteen triples the Sentry Gun's firing rate. An Upgrade Buildings Canteen instantly upgrades the Sentry to Level 3 as well as fully repair it, however it does not refill the Sentry Gun's ammo. Sentry Guns can also be upgraded at Upgrade Stations to increase their health and firing rate, and the Engineer can even buy a Disposable Sentry Gun, allowing him to place a second Mini-Sentry that is slightly worse than a Combat Mini-Sentry.
Vulnerabilities
Sentry Guns are damaged by most weapon effects that damage players; however, some effects are modified for Sentry Guns. Also, weapon damage done to a Sentry Gun does not suffer from range falloff, with the exception of any scatter-based weapons or indirect explosions. A destroyed Sentry Gun drops 65 Metal worth of scrap pieces, which can also be picked up by other classes as Ammo.
Sentry Guns do not fire upon enemy Spies that are cloaked. In general, Sentry Guns do not fire upon enemy Spies that are disguised; however, if the Sentry was firing upon the Spy at the time the disguise was activated, it continues to fire upon the Spy until the Spy cloaks, breaks line of sight, or moves out of range. Sentry Guns also do not fire upon enemies in its range if there is a water surface between them or if the enemy is behind cover – this cover includes the Engineer's Dispenser. Sentry Guns are also unable to fire if an enemy Spy attaches a Sapper to it or while they are being upgraded/built. Feign deaths produced by the Dead Ringer are not added to the Sentry Gun kill/assist counter but do contribute to the Best Little Slaughterhouse in Texas achievement.
An Engineer is vulnerable to damage from his own Sentry Gun's bullets. For about the first 300 Hammer units of their flight, Sentry Gun rockets pass through the Sentry Gun's Engineer without detonating as if he were another member of the same team. However, if the rockets do strike another surface within this distance and explode, the Engineer is vulnerable to the resulting splash damage. Beyond this initial distance, the Engineer is fully vulnerable to his own Sentry Gun's rockets (the knockback from Sentry Gun self-damage enables the Engineer to perform bullet and Sentry rocket jumps, especially with the aid of the Wrangler).
Metal spending priority
When an Engineer hits a Sentry Gun with their melee weapon, the metal is spent in a certain order:
- Health
- Upgrade Progress
- Ammo
- Bullets
- Rockets
However, ammo is usually filled alongside Health and the Sentry Gun's Upgrade Progress. Bullet ammo is refilled first, followed by rocket ammo.[1]
Demonstration
Combat Mini-Sentry Gun
| “ | Ain't that a cute little gun?
Click to listen
— The Engineer on his Mini-Sentry
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” |
The Combat Mini-Sentry Gun, also known as Mini-Sentry or simply Mini, is a more combat-efficient version of the standard Sentry Gun and is a component of the Engineer's Gunslinger unlock. It is a smaller Level 1 Sentry Gun outfitted with a rotating light that glows and is painted with a white checkered paint. Like the Sentry Gun, it can be hauled.
Demonstration
Advantages
- Costs only 100 Metal to place (the normal Sentry costs 130 Metal). This allows an Engineer at a full 200 Metal to build both it and a Dispenser without needing additional Metal.
- Constructs much faster than the original Sentry Gun. Hitting the Sentry makes it construct faster and, when deployed after hauling, it is armed in 1.5 seconds.
- Cheap and disposable means of area denial.
- Begins construction with 50 health. This makes the Mini-Sentry less vulnerable while under construction when compared to the default Sentry Gun, which begins construction with 1 health.
- Fires 25% faster than a Level 1 Sentry Gun.
- Can rotate 35% faster than the default Sentry Gun.
- 75% the size of a regular Sentry Gun, making it harder to notice and hit.
- More useful for Sentry jumping, as the firing rate and reduced damage combine to deal more knockback for an equivalent health loss.
Disadvantages
- Has only 100 health, compared to a Level 1 Sentry Gun's 150.
- Cannot be upgraded. The owner and other Engineers can still refill its ammo and health.
- Deals only 50% the damage per shot of the original Level 1 Sentry Gun. Combined with the 25% faster firing rate, the damage per second is overall 38% lower (~50 DPS compared to the Level 1 Sentry Gun's ~80 DPS).
- Bullets apply significantly less knockback force (800% knockback multiplier compared to a regular Sentry Gun's 1600% multiplier).
- Drops zero Metal when destroyed.
Disposable Mini-Sentry
In Mann vs. Machine, the Engineer can buy a Disposable Mini-Sentry that at first glance just looks like a Combat Mini-Sentry Gun; however, there are a few differences:
- Has a slower firing speed than a regular Mini-Sentry.
- Cannot be repaired or have its ammo refilled.
- Cannot be destroyed by the Engineer who made it — it can only be destroyed by an enemy robot or a Tank if it's placed on its path.
- Outside damage sources, the Disposable Mini-Sentry will also be automatically destroyed when a wave is finished or when it runs out of ammo.
- Cannot be wrangled, but still receives canteen buffs.
- Has 66% the size of a normal Sentry Gun, compared to the Combat Mini-Sentry Gun's 75% size.
- Is not affected by the building health upgrade (maximum health cannot go past 100).
- Is, however, affected by the Sentry Firing Speed upgrade.
Sentry Gun Levels
| Level | Kill icon | Health | Cost (Metal) |
Weaponry | Damage | Ammo | ||
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Without Wrangler shielding: 150
With Wrangler shielding: 450 |
130 | Single barrel machine gun |
Damage
Attack interval
Average DPS
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150 rounds | ||
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Without Wrangler shielding: 180
With Wrangler shielding: 540 |
330 | Twin-mounted Gatling guns |
Damage
Attack interval
Average DPS
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200 rounds | ||
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Without Wrangler shielding: 216
With Wrangler shielding: 648 |
530 | Twin-mounted Gatling guns and rocket salvos | Gatling guns
Damage
Attack interval
Average DPS
Rockets Damage
Falloff is calculated from the distance of the Engineer to the target, not from the Sentry to the target Attack interval
Note: Can be reflected with the Pyro's compression blast |
200 rounds 20 rocket salvos | ||
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Without Wrangler shielding: 100
With Wrangler shielding: 300 |
100 | Single barrel machine gun |
Damage
Attack interval
Average DPS
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150 rounds | ||
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100 | Without Gunslinger: 130
With Gunslinger: 100 |
Single barrel machine gun |
Damage
Attack interval: 0.225 seconds Average DPS: 35.56 - 42.22 Note: Only available in Mann vs. Machine as an upgrade and cannot be wrangled, repaired, or have its ammo refilled. |
150 rounds |
Advanced tactics
Related achievements
General achievements
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Scout
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Soldier
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Demoman
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Engineer
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Medic
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Sniper
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Spy
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Mann vs. Machievements
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Update history
- Fixed Sentry muzzleflashes not drawing unless sentry was near the map origin.
- Engineer buildings now explode when the Engineer dies during sudden death.
- Fixed a bug in scoring Engineer building destruction.
- Sapped buildings now take slightly less damage from the Spy who sapped them.
- [Undocumented] Fixed model exploit in stage one allowing Sentry Gun/Teleporter to be placed behind chain link fence on Dustbowl.
- Added server log entry for buildings destroyed by their owner.
- Fixed Sentry Gun shadows being clipped.
- [Undocumented] Changed Engineer buildings to detonate when a player disconnects instead of blinking out.
- [Undocumented] Fixed Engineer being able to detonate buildings that are being sapped.
April 29, 2008 Patch (Gold Rush Update)
- Mapmakers can now place Engineer buildings directly into a map, with an option for them to be invulnerable.
- Fixed Sentry Guns firing at a fully cloaked Spy if they're still the closest target.
- Killing yourself with your own Sentry Gun no longer increments the Sentry Gun's kill counter.
- Fixed the Engineer being able to build more than 1 of each type of building.
July 8, 2010 Patch (Engineer Update)
- Added the ability to haul or move your Sentry Gun, along with having the Wrangler control the Sentry Gun
- Added a laser light to all sentry models.
- [Undocumented] 'Wrenching' a Sentry Gun now upgrades, repairs and restores ammunition all at once per Wrench hit, prioritizing repairs and upgrading if not in possession of enough metal.
- Fixed an exploit that allowed Engineers to build level 2 or 3 mini Sentry Guns.
- Fixed an exploit where Engineers could create level 3 mini-Sentry Guns.
- Fixed an exploit that allowed team kills with Wrangled Sentry Guns.
- Fixed a Sentry Gun exploit that let Engineers build multiple Sentry Guns.
- (Supposedly) Fixed Engineers being able to build level 3 mini-Sentry Guns using the Wrangler.
- Fixed another Sentry Gun exploit that let Engineers build multiple Sentry Guns.
- Fixed Engineers being able to build level 3 mini-Sentry Guns using the Wrangler (for real this time).
December 17, 2010 Patch (Australian Christmas)
- Sentry Guns no longer track Your Eternal Reward Spies after they backstab someone.
- Updated Sentry kill icons.
- Combat Mini-Sentry is given a kill icon.
- Fixed the mini-sentry HUD not playing the alert sound when the sentry is sapped or low on ammo.
- Engineers who hit teammate's Sentry Guns with their Wrench now get kill assists from that Sentry Gun.
March 10, 2011 Patch (Shogun Pack)
- Fixed the "Best Little Slaughterhouse in Texas" Engineer achievement not counting Wrangler and Mini-Sentry kills.
May 5, 2011 Patch (Replay Update)
- [Undocumented] Sentry Guns now properly target the Horseless Headless Horsemann as an enemy.
- Fixed being able to place buildings in nobuild zones.
June 27, 2012 Patch (Pyromania Update)
- Fixed sentry sometimes spawning in shielded mode while the Wrangler was equipped, but not deployed.
- Fixed Sentry Gun sometimes placing wrong, being rotated into the ground and pointing upward.
- Fixed a bug where Sentry Guns would not rotate to face their target under some circumstances.
- Fixed a bug that allowed level 3 mini-Sentry Guns in Mann Vs. Machine mode.
- Fixed the Mini-Sentry range-sphere not accurately displaying the range for the sentry when it is being placed.
- Fixed a UV/skinning problem on the level 1 Sentry Gun.
- Fixed a bug that would cause the Sentry Gun’s health to look overhealed when it wasn’t.
- Sentry bullets are now affected by damage falloff outside of sentry scan range.
- Sentry bullet damage has been changed so it calculates damage based on the Sentry Gun's position, not the Engineer's.
- Fixed Mini-Sentry collision hull and hitbox being scaled smaller than they should be.
- Added enemy team
func_nobuildvolumes to the capture zone areas inctf_foundryandctf_gorgeto prevent spawn-camping Sentry Guns.
- Fixed Sentry Guns shooting over the head of Spies using the Box Trot taunt.
July 23, 2015 Patch #2
- Fixed Sentry Guns having unlimited ammo.
- Fixed Sentry Gun model being set to level 1 after a Sapper is removed.
December 17, 2015 Patch (Tough Break Update)
- After removing a Sapper from a Sentry Gun, there is now a 0.5s delay before the sentry is active again.
- Sentry Guns brought into a respawn room no longer detonate outside of Mann vs. Machine.
- Fixed a bug with Sentry Guns being disabled for 5 seconds instead of the desired 0.5 seconds after a Sapper is removed.
- Fixed mini-Sentry Guns not having full health when they are built quickly during the setup time on Mann vs. Machine maps.
- Fixed an exploit where Sentry Guns could fire through thin walls.
- Fixed Mini-Sentry Guns not triggering damage alerts in the HUD
Bugs
- The player has the ability to build the Combat Mini-Sentry Gun, while having any wrench equipped, by holding out the blueprints for the Sentry with the Gunslinger and then quickly switching to a wrench. The player builds a Mini-Sentry (it still costs 130 Metal). This cannot be done vice versa (equipping the Gunslinger while having normal Sentry blueprints out). If this is done with the Jag the Sentry gets the construction boost effect.
- Sometimes, when an upgraded Sentry is moved, it fires a bullet between upgrade stages if pointed directly at an enemy or Wrangled.
- Rarely, after removing a Sapper, all of the Sentry Gun's ammunition, including rockets, is completely gone.
- A Wrangled Sentry does not play its rocket-reloading animation.
- Wrangling a Combat Mini-Sentry Gun might result in it remaining in the Wrangled state even when the Wrangler is not the currently active weapon.
- Switching back to the Wrangler corrects the problem.
- After the Mini-Sentry finishes its building animation, it sinks into the ground slightly.
- Occasionally, after being built, a Level 1 Sentry might be frozen in animation and not fire any bullets.
- There still exists a way to get a Leveled Mini-Sentry on some custom maps.
- Sometimes, when a Spy saps the Sentry Gun during it being constructed, the Engineer cannot destroy the Sapper, making him have to destroy the Sentry Gun, or let the Sapper destroy the Sentry Gun.
- Rarely, when a Sentry Gun has been sapped and the Engineer has changed class or left the game, the Sapper appears floating in the air.
- The damage of the Sentry Gun's rockets is calculated based on the distance between the enemy and the Engineer, not the Sentry Gun. Therefore, if the Engineer is closer to the enemy being targeted by the Sentry Gun, it does more damage.
Unused content
- An unused alternate kill icon for the Level 1 Sentry Gun exists in the game files.
Trivia
- Radigan Conagher created modern Sentry Gun designs by 1890.[2] The 1890 and current designs are visually identical.
- Radigan Conagher's notes suggest an earlier steam-powered Sentry Gun design.
- Valve ordered and received a full-size motion-tracking model of a Level 1 Sentry Gun from Weta Workshop.
- Clicking "View the manual" button on the Steam store page of Team Fortress 2 opens an online PDF file of the Sentry Operating Manual.
- The Sentry Operating Manual uses the recycling symbol to tell players they can reuse metal from destroyed equipment. However, that the sign was not created until 1970.
- The cover of the Sentry Operating itself is more like that of the late 1950s to early 1960s, whereas the game itself takes place in July of 1968 (The Calendars). By that point, the font of "Sentry" was outdated and was no longer being used. Industrial (upon which the game is heavily based) used a very basic font even before that.
- The Sentry Operating Manual is in color, which would be wrong for an industrial manual as most are not in color, especially during the 20th century.
- On the back of the Level 3 Sentry Gun's rocket salvo, a tab connects three of the four rockets to the device.
- In Payday 2, on a train robbery mission, the robbers steal a Level 1 Sentry Gun.
Gallery
- Sentry Gun levels
Level 1 Sentry Gun.
Level 2 Sentry Gun.
Level 3 Sentry Gun.
Combat Mini-Sentry Gun.
Build to Level 3 animation.
- Development
Sentry Gun concept art.
Sentry Gun concept art.
Sentry Gun explosion.
Sentry Gun concept art.
Sentry Gun models with ambient occlusion.
- Storyline
The Storyline was expanded within the Engineer Update. From Loose Canon, the Sentry Gun Manual, and the Engineer Update Page, it is inferred that Radigan had developed the modern Sentry design before exposure to Australium and that the Engineer obtained the Sentry plans in the early 1960s from his grandfather's notes.
Radigan's steam-powered Sentry design.
Radigan's 1890s advanced Sentry design.
- Sentry Gun Operating Manual
Front Cover.
Page 2.
Page 3. Sentry Gun Components.
Pages 4-5. Modifying your Sentry.
Back Cover.
- Other images
Icon for a hauled item being destroyed via the Engineer's death.
Unused Sentry kill icon.
Merchandise
References
- ↑ Uncle Dane - Engineer Rules
- ↑ Loose Canon comic, page 8, Retrieved 2019-03-17
