If you're reading this manual, you're the proud new operator of Armat Systems' tried and tested line of semi-automated sentry turrets, the UA 571-C Sentry Gun. Congratulations! This lethal new device is as beautifully crafted by the finest Armat engineers as it is deadly. The sentry that is, not the engineers. They're fairly ugly.
Woh, woh! Don't just read the first few sentences and throw away the manual! You should know how to construct, maintain, and operate this device to the utmost before you begin spraying M30 Autocannon bullets with wild abandon. The UA 571-C requires tender care and constant maintenance to ensure it's fit for front-line support, and can be extremely dangerous if not handled properly. Let's get started, shall we?

Figure 1.0: The Crate, the Beautiful Crate
You'll first notice that your UA 571-C Sentry comes in a handy carrying tote, which itself is something of a collector's item due to its smooth velour interior. It's okay to run your hands over the crate for a few minutes. Feel that luxurious plastic. It's alright. Nobody will notice. The crate comes with everything you need for constructing your UA 571-C Sentry minus a few common tools.

Figure 1.1: Inside the Crate
Inside your UA 571-C Sentry Crate you'll see the following items:
a) 20 sheets of plasteel. Use these in a suitable spot to construct the initial turret frame.

Figure 1.2:: Turret base frame
b) 10 sheets of metal. These are for finalizing the turret's armor frame.
c) M30 Autocannon frame. This is mounted on the turret frame and comes pre-installed with 300 rounds of ammunition.
d) Targeting AI Sensor. This sensor is used to find your hated enemies, like maybe the Mexicans. (editor's note: are we at war with the Mexicans yet?)
e) Spare power cell, for when your sentry runs out of kill-juice.
f) Spare 300-round drum magazine, for when your sentry runs out of kill-metal.
So, how do you assemble all this stuff? Great question!

Figure 1.3: Construction loop
Begin by constructing your turret frame. Apply the following steps to the frame:
a) Wrench it in place. After this point it will not be able to move, so choose wisely!
b) Install the wiring. It's as easy as jamming a bunch of wires in there until it looks wiry.
c) Stick the M30 Autocannon on top. It will latch into place thanks to the interlocking latching mechanisms.
d) Plug in the computerized sensor. Luckily it cannot be installed upside-down.
e) Place metal sheets in the various slots around the turret frame and cannon.
f) Weld the entire thing together.
Success!

Figure 1.4: Fully constructed and ready to murder!
The panel on your UA 571-C Sentry Gun has a number of different functions. Before you turn the panel on, find the safety datasheet and study it carefully. NEVER stand in front of an activated Sentry Gun!

Figure 1.5: Sentry Gun Control Panel
Your control panel has everything you need to perform various actions with your new toy. It has a live ammo counter and power cell charge meter - if it runs out of ammunition or power, simply hit it with a new box magazine or power cell of any size to replenish it. Simply being activated means the Sentry Gun must draw energy, so if you are using basic power cells expect to have to recharge it often.
A) Turn off your Sentry Gun for cleaning, maintenance, or because your neighbours walked in front of it
B) Direction Cycle Lock -- this function, when ON, focuses the sensor array in FRONT of the sentry gun in a cone:

Figure 1.6: Sentry Sensor Cone. Note: All personnel seen in this image are static target dummies. No monkeys were hurt in the production of this field manual.
This will allow it to target any hostile enemy in a long range, assuming they are within a 90 degree firing arc of the gun.
When the direction cycle is OFF, the sentry is capable of full 360 degree rotational movement. However, the sensor is not able to perform as well and can target only those in fairly close range.

Figure 1.7: 360 NoscopeRotational Range
C) Burst Fire Toggle. When in burst fire mode, the UA 571-C is capable of firing a rapid 3-round burst at any acquired targets. However, it leads to significant instability in the gun platform and shots are much more widely spread than in single-shot mode. Therefore, single-shot is recommended at most times to conserve ammo and power levels.
D) Safety Toggle - Not functional at this time
E) Manual Override - Manual Override allows you, the discerning soldier, to take personal command of the UA 571-C Sentry Gun and turn it into a controlled hardpoint. It can only be done in static direction cycle lock mode. When toggled, anywhere you point to in front of the sentry will be shot at, without any regard to target aquisition. Be careful! "Accidently" shooting your commanding officer in the brain 60 times is grounds for a court-martial!
F) Close the panel.
So how does the UA 571-C Sentry Gun acquire its targets? Good question! It locks in on the carbon output of any creature within its sight cone. However, when it determines that the target has sustained life-threatening damage, it will move on to a different target, to avoid wasting ammunition and power. It acquires human targets primarily by ID tag -- better keep that ID worn on your suit, soldier!

Figure 1.8: This poor janitor forgot his ID in the bathroom. Woops!

Figure 1.9: 360 Rotational Fire
Which brings us to the final section, maintenance.
You can rotate your UA 571-C Sentry Gun to face a different direction, but not while it is turned on. Turn it off, and then use a wrench on it.

Figure 1.91: Ratchet & Clank
Reloading your UA 571-C Sentry Gun is a breeze, simply hit it in the sweet spot with a power cell or a box magazine (which can be ordered at any Weyland Yutani Corporate Requisitions Headquarters)

Figure 1.92: Loving Your Sentry
A few things to bear in mind, however--
Your sentry is not invincible! If it takes sufficient damage, it will fall over. It can be righted again simply by picking it up. Try to avoid accidently being shot in the face. If your sentry takes damage, simply use a welding tool on it for repairs.
If a sentry gun is destroyed, there's a significant risk the computerized servos may begin sparking, and could cook off the ammunition holding chamber. In this situation, it is definitely advisable to avoid being anywhere near the sentry and simply order a new one.
In the case of accidental fire, unintended target aquisition, massive unintentional slaughter, available paint job packages, or if you are otherwise not fully satisfied with your new UA 571-C Sentry Gun, please contact your Weyland Yutani representative or a local Armat Systems field operative for replacement.
You can LOCK or UNLOCK your sentry gun's control panel by hitting it with an ID with sufficient access. This is: Engineer or Squad Leader.
UPDATE:
The UA-571-C Sentry Gun is now updated with the latest IFF friendly-fire transponders, allowing it to fire through anyone wearing an ID. So stand in front of it all you please!
In addition, the Sentry Gun can now be moved as long as it is turned off. Just unscrew it from the ground and off you go!
Armat Battlefield Systems.
Peace Through Superior Firepower.