Mini-turret

The mini-turret is a stationary defense mechanism which automatically fires at any enemies entering its range of 24.9 tiles. It fires a 3-round burst with no need for warmup, has a slow 4.8 second cooldown and 96% per-tile accuracy. While turrets are somewhat underwhelming on their own, large groups of turrets are able to incapacitate or kill small groups of hostiles within seconds.

After firing 120 rounds it requires a barrel change, costing:

20 steel in Peaceful and Base Builder difficulty
30 steel in Medium difficulty
40 steel in Rough difficulty and above

Turrets have a 50% chance of exploding when it reaches 20% health.

Construction

Constructing the turret requires research in microelectronics basics and gun turrets (some scenarios have Gun Turrets already researched).

Alternatively, it can be opportunistically uninstalled and looted from various world sites.

Material	Steel Cost	Cost	Hit Points	Flammability (%)	Market Value	Beauty
Steel	100	3	120	28	300	-20
Plasteel	40	3 + 60	335	14	740	-20
Uranium	40	3 + 60	300	0	555	-20
Silver	40	3 + 600	84	28	785	-14
Gold	40	3 + 600	72	28	6,185	0

Materials

Steel is the most viable option early-game, but it's advisable to switch them out for plasteel turrets as soon as you can, as steel turrets aren't very durable and therefore can't withstand sustained gunfire.
The most effective material is plasteel. It has the most HP, very low flammability, is somewhat easier to obtain mid-late game, and saves steel for other purposes.
You should expect turrets to be frequently replaced, and uranium is too rare and expensive to be practical.
Silver and gold are poor material choices due to their poor durability.

Images

Steel Mini-Turret
Plasteel Mini-Turret
Uranium Mini-Turret
Silver Mini-Turret
Golden Mini-Turret

Visualization of effective turret range of all three turrets, from uranium slug turret (top), to autocannon turret (middle), to mini-turret (bottom).
Green is 80 - 100% of peak accuracy, blue is 50 - 80% of peak accuracy, red is below 50% of peak accuracy and grey is outside range. Gold tiles are spaced every 5 tiles.

Tactics

Used alone or in small numbers, turrets do not provide much additional firepower. However, raiders will often target the turret instead of the colonists if it is closer to them, shielding the colonists from harm until the turret is destroyed. However, attackers will not take an unpowered turret as a primary target. The firepower of the turrets adds up when massed together, to the point where turrets alone can sometimes beat back even massive raids. Larger colonies often build a "killbox": An entrance area designed to funnel raiders where turrets can do maximum damage while the raiders' own ability to fight back is minimized. Using Sandbags to protect your turrets can be a solid tactic in either case. Raiders with long ranged weapons can snipe a turret from outside its range, so forcing them into close range with walls or terrain is recommended.

Turret explosion

Turrets have a 50% chance to explode when it reaches 20% health. The exploding turret will spark and emit a hissing sound that increases in pitch shortly before exploding a few seconds later. All nearby raiders will run in an attempt to get out of the blast radius to keep their skin intact.

The explosion deals 400 damage to all walls within its 3.5-tile blast radius, 200 damage to all other structures and furniture, and 50 damage to the slag chunks and components that drop, and around 50 damage (usually split across multiple body parts) to all pawns unlucky enough to get caught in the explosion. Due to this, it's best to space out groups of turrets so that one exploding doesn't create a chain reaction. This is somewhat less of a risk with Plasteel turrets.

Graphs

The below shows accuracy and DPS of a turret across its range.

Version history

Prior to Beta 19, it used to be called the Improvised turret. It also used more power (350W) and costed more to build, but did not require barrel changes.

Architect

Security: Barricade • Sandbags • Spike trap
(research): Autocannon turret • Foam turret • Mini-turret • Rocketswarm launcher • Uranium slug turret • Mortar
IEDs: IED trap • IED incendiary trap • IED EMP trap • IED firefoam trap • IED smoke trap • IED antigrain warhead trap • IED tox trap
Related: Antigrain warhead • EMP shell • Firefoam shell • High-explosive shell • Incendiary shell • Smoke shell • Tox shell