The M231 Firing Port Weapon is only intended to be used inside the Bradley AFV in a special mount. Hits hard, but good luck hitting anything...
... You're going to use it anyways, Boss?
–In-game description
M231 angled
Weapon Type Primary Weapon
Weapon Class Assault Rifle
Rank Prerequisites Rank 123
Damage 35 → 25
Range 90 max → 150 min


Hip Accuracy


Sight Accuracy


Magazine Size 30
Ammo Reserve 150
Fire Modes Auto
Rate of Fire 1225 RPM

TTK (Time to Kill) 0.09 s
Head & Body Multiplier
per bullet/pellet
Max (90 studs) Min (150 studs)
(x1.40) Head 49 35
(x1.00) Torso 35 25
(x1) Arms and Legs 35 25
Red color signifies a fatal hit.
Suppressed Stats
Suppressor/Bullet Attachment Suppressed Damage Suppressed Range
ARS Suppressor 35 -> 22.5 90 max -> 150 min
R2 Suppressor 33.25 -> 23.75 85.5 max -> 142.5 min
PBS-1 Suppressor 33.25 -> 23.75 85.5 max -> 142.5 min
PBS-4 Suppressor 33.25 -> 23.75 85.5 max -> 142.5 min
Suppressor 31.5 -> 25 81 max -> 150 min
Armor Piercing 35 -> 20.83333 0 max -> 150 min
Hollow Point 42 -> 30 90 max -> 150 min
Muzzle Velocity 2200 studs/s
Penetration Depth 1.0 studs
Suppression 0.5


Hipfire Camera Recovery Speed 23
Sight Camera Recovery Speed 22
Weapon Recovery Speed 22
Weapon Recoil Damping 0.9


Min Camera Kick (3.29, -0.61, -0.31)
Max Camera Kick (4.69, -0.11, 0.30)
Min Recoil Displacement (-0.50, 0.60, 7.19)
Max Recoil Displacement (0.80, 1.10, 8.50)
Min Recoil Rotation (1.60, 0.50, -0.31)
Max Recoil Rotation (4.19, 1.20, 0.30)
Hipfire Spread Factor 0.08
Hipfire Recovery Speed 10
Hipfire Spread Damping 0.60


Min Camera Kick (1.50, -1.30, -0.50)
Max Camera Kick (4.09, 1.29, 0.50)
Min Recoil Displacement (-0.11, 0.20, 5.19)
Weapon Shot Displacement (0.10, 0.40, 6.80)
Min Recoil Rotation (2.20, -0.25, -0.31)
Max Recoil Rotation (4.50, 0.25, 0.30)
Sight Magnification 1.8x


Reload Time 1.9 seconds
Empty Reload Time 2.7 seconds
Equip Speed 12
Aiming Speed 17
Crosshair Size 30
Crosshair Spread Rate 300
Crosshair Recover Rate 15


Weapon Walk Speed 14 stud/s
Aiming Walk Speed 9.7 stud/s
Ammo Type 5.56x45mm NATO
Round in Chamber One
Shot Suppression Range None

List of Attachments

Optics Kills Required
Z-Point 10 Kills
H&K Sight 20 Kills
EOTech XPS2 45 Kills
Delta Sight 70 Kills
MARS 70 Kills
EOTech 552 85 Kills
Mini Sight 110 Kills
C79 125 Kills
Comp Aimpoint 130 Kills
PK-A 165 Kills
M145 185 Kills
PKA-S 225 Kills
PSO-1 Scope 240 Kills
Reflex Sight 285 Kills
Kobra Sight 320 Kills
Super Slim Sight 350 Kills
Coyote Sight 380 Kills
ACOG Scope 430 Kills
VCOG 6x Scope 455 Kills
Pilad 3 500 Kills
TA33 ACOG 650 Kills
Barska Electro 750 Kills
OKP-7 900 Kills
DDHB Reflex 1200 Kills
TA11 ACOG 1750 Kills
PSO-1M2 Scope 2250 Kills
TA01 ACOG 2500 Kills
Animu Sight 4500 Kills
Furro Sight 5000 Kills

Underbarrel Kills Required
Angled Grip 115 Kills
Vertical Grip 45 Kills
Folding Grip 265 Kills
Stubby Grip 355 Kills
Laser 75 Kills
Flashlight 0 Kills

Barrel Kills Required
ARS Suppressor 150 Kills
Compensator 120 Kills
Muzzle Brake 175 Kills
R2 Suppressor 40 Kills
Flash Hider 100 Kills
PBS-4 Suppressor 245 Kills
PBS-1 Suppressor 205 Kills
Suppressor 30 Kills

Other Attachments Kills Required
Green Laser 110 Kills
Canted Delta Sight 405 Kills
Laser 20 Kills
Canted Iron Sight 310 Kills
Ballistics Tracker 1500 Kills
Hollow Point 2000 Kills
Armor Piercing 1000 Kills

The M231 is an American Assault Rifle. It is unlocked at rank 123, or it can be purchased with credits.


The M231 FPW (Firing Port Weapon) is an open bolt firearm and was designed for the M2 Bradley infantry fighting vehicle. The Rock Island Arsenal worked with the World War 2-era M3 submachine gun, another FPW based on the HK33, and an adapted AR-15/M16-pattern weapon before deciding that the last weapon had promising qualities and was given the designation XM231. Colt was given the contract for the weapon and continued working on the design, and the weapon was finalized in 1979 and adopted as the M231.

The original Rock Island Arsenal XM231 fired from an open bolt, giving the weapon an incredible rate of fire, at 1050 RPM (Rounds Per Minute). After Colt received the design, a special buffer and spring assembly limited the rate of fire to 200 RPM, thereby eliminating the risk that users would expend their ammunition before their weapon was brought to target.

At some point during development, the weapon's fire rate was reintroduced at the 1100-1200 RPM range.

Officially, the M231 is not to be detached from its parent vehicle unless in an emergency, and the operator's manual warns of precautions that would have to be taken when using the weapon outside the vehicle. In-game, these rules are ignored.


General Information

The M231 is a powerful, fast-firing, high recoil assault rifle. Damage is quite good for its class, being capable of eliminating a target with a three-shot kill (3SK) to the body within 100 studs. Beyond this range, the M231 will 4SK to the body, however, it will always eliminate a full health enemy with three headshots, unless using certain suppressors. The range is fairly good, given the higher damage overall. Muzzle velocity is less-than-average, however, at just 2200 studs per second. However, as stated later, this is somewhat difficult to apply effectively.

Rate of fire (RoF) is extremely high, at 1225 RPM—the fastest firing fully-automatic assault rifle in-game. Paired with the good damage, the weapon's time to kill (TTK) is extremely quick at all ranges, provided the user manages to hit all shots consistently. Recoil is as equally as high, however, with the weapon kicking quite high vertically with some horizontal movement. Due to this, the effective range is reduced. Furthermore, the high RoF means the weapon has very little time to return back to the user's original aiming position, meaning holding down the trigger will make a user's aim easily drift above an enemy's head. Per shot recoil is moderate, however, making tap-firing or burst-firing useful to limit the impact of recoil. Even with the usage of recoil-reducing attachments, some may struggle with the recoil.

Uniquely, the M231 lacks proper iron sights. This makes aiming and subsequently controlling recoil whilst aiming-down-sights (ADS) quite difficult as a visual representation of the user's point-of-aim is not present. Muzzle flash is also quite high, making target acquisition whilst firing without attachments quite difficult.

Magazine capacity is standard for an assault rifle, at 30 rounds, being unable to chamber an extra round. Interestingly, the M231 has 150 rounds in reserve than the regular 120 rounds of an assault rifle, resulting in having more total ammunition than any other assault rifle. Given the very high fire rate and subsequently very high ammunition consumption rate, the extra 30 rounds is beneficial. The M231 also benefits from having a common ammunition type, meaning that replenishing ammunition is fairly easy to do.

Usage & Tactics

Given the lack of a proper iron sight, an optic is a necessity for accurate shot placement. Low magnification optics such as the Reflex Sight or AMT-Terminator are good choices, as their low magnification lessens the impact of the visual recoil. As well as this, these sights also have small housing frames, meaning they are less obstructive when either aiming down sights (ADS) or hipfiring. However, which sight is chosen is subject to a user's preference. High magnification optics tend to exacerbate the high recoil, making them unsuited for the M231, especially when firing in full-auto. With tap-firing it is possible to utilize high magnification optics—the high minimum damage allowing for fairly good long-range performance—although this does require a high degree of skill from the user.

Recoil-reducing attachments help to somewhat mitigate the extreme recoil of the M231, but M231 is incredibly demanding on a user's ability to effectively control the recoil. Burst-firing and tap-firing are essential for engagements outside of CQC and also conserving ammunition. Full-auto should be restricted to CQC. Regarding grips, the use of an AngledStubby or even Folding Grip can somewhat help in taming the recoil, but the M231 remains a difficult weapon to control in fully-automatic fire, even occasionally in close-quarters-combat (CQC). If one was less focused on precision, the Vertical Grip offers an alternative to those looking for a more aggressive class build, designed for spraying from the hip.

Regarding barrel recoil-reducing attachments, they are less effective. The Muzzle Brake is the most effective out of the two, lowering the high vertical recoil, but the high degree of muzzle flash makes the need for either a suppressor or flash hider paramount. The compensator can be useful if the user wants to reduce the horizontal recoil. Grips remain more effective in reducing recoil in comparison, and so a user can forgo the use of a recoil-reducing barrel attachment with only a minimal difference in performance, in favor of a more useful option in regards to view on target.

The Flash Hider is a great option for those seeking the removal of muzzle flash without the downsides of using a suppressor. Although it will make the weapon less stable. 

Suppressors both remove the muzzle flash and keep the user off of the minimap whilst firing, both beneficial traits to possess, the latter particularly useful in CQC. Depending on the suppressor, the penalty to damage, range and muzzle velocity varies. Some preserve the 3SK up close at the cost of steeper damage drop-off or worse minimum damage; resulting in a 5SK at long range, whereas others heavily hamper muzzle velocity and worsen the weapon's long-range performance. However, given the very high RoF and CQC power of the M231, the negative impacts on minimum damage and muzzle velocity are somewhat negated by the benefits of using a suppressor.

In regards to attachments from the Other category, lasers are valuable to any class build—improving hipfire performance by providing a visual indication of where bullets will land when firing when not ADS. Attachments such as the Canted Sights can work when paired with a high-magnification optic such as the ACOG Scope, although such a pairing is not as effective given the high recoil. The Ballistics Tracker is largely ineffective given the CQC nature of the weapon. The wire stock can help with recoil to some degree but is generally unsatisfactory as the user has to sacrifice either a Laser or grip to accommodate it. One workaround is by using the MARS or AMT-Terminator sight for its integrated laser. Should the user want to reduce recoil even further, the choice of .223 Remington ammo is also available, reducing recoil at the cost of damage and velocity.


The M231 is a CQC oriented weapon. With the damage of an assault rifle and the RoF of a PDW, it can be quite powerful once the user has mastered the recoil. It's fast reload speed can be handy, especially when the magazine is expended due to its fast RoF. Provided with good recoil control and the right attachments, the M231 can be a powerful weapon.

Pros & Cons


  • Good damage.
  • Good hipfiring stability.
  • Fast reload time.
  • Above-average ammunition reserve total for its class at 150 rounds.
  • Very Common ammunition type, can pick up ammunition from ARs, Carbines, and weapons using 5.56x45mm NATO rounds.
  • Extremely high RoF for its class.
  • Has an alternate aim point like an LMG.


  • Extremely high vertical recoil, cannot be mitigated effectively with attachments.
  • Very high ammunition consumption rate.
  • Below average muzzle velocity for its class.
  • Restricted to fully-automatic.
  • High muzzle flash, obstructs aiming.
  • Lack of iron sights, requiring extreme aiming precision.
  • Open bolt weapon; unable to chamber a round.


  • In the 4.14.0 update, a wire stock attachment has been made for the M231, though it does little to help the recoil.
    • The wire stock has been borrowed from the M3A1.
  • The M231 has been nicknamed the "Troll gun", a nickname brought by the Stylis Studios developers who designed the M231 in-game to be virtually useless and uncontrollable to experienced and inexperienced players alike. Despite this, some players have been able to use the M231 effectively, despite the implied definition of a "Troll Gun."
  • Before the July 4, 2017 update, the M231, when equipped with a VCOG 6x Scope and a Canted Iron/Delta Sight, it had virtually no recoil. This bug has since been patched.
  • Before the July 4, 2017 update, the M231 used to have a semi-automatic fire mode. Combined with the VCOG scope, the M231 became a very effective DMR. This fire mode has since been removed.
    • This was also due to the M231 not having a semi-automatic fire mode in real life and balance reasons.
  • In the 3.10.0 update, attaching a VCOG on the M231 lowered the visual recoil. This was patched in the 3.11.0 update.
  • The M231 is the only AR-15 platform weapon in-game not to have a rear or front iron sight, and the second weapon in-game to not have any sights at all (first being the Obrez). 
    • The lack of aiming posts is due to the real-world usage of tracer rounds. In real life, the M231 FPW uses the M196 tracer rounds, which are used to help the user to readjust their aim during automatic fire.
  • The M231 is currently the only weapon in the game that is usable that is meant to specifically be mounted in a vehicle, designed to be fired from the inside of the M2 Bradley.
  • The weapon's description has a callback to Metal Gear Solid, specifically Metal Gear Solid 3, where The Boss uses a heavily modified short-barrel AR-15 platform rifle with a Beta C-Mag magazine called the Patriot.
Primary Weapons

Assault Rifles

AK12 - AN-94 - AS VAL - SCAR-L - AUG A1 - M16A4 - G36
M16A3 - AUG A2 - FAMAS F1 - AK47 - AUG A3 - L85A2
HK416 - AK74 - AKM - AK103 - TAR-21 - M231 - G11K2

Personal Defense Weapons

MP5K - UMP45 - G36C - MP7 - MAC10 - P90 - MP5
Colt SMG 633 - L2A3 - MP5SD - MP10 - MP5/10 - Uzi - M3A1
AUG A3 Para - PPSh-41 - FAL Para Shorty - Kriss Vector
MP40 - X95 SMG - Tommy Gun

Light Machine Guns

Colt LMG - M60 - AUG HBAR - MG36 - RPK12 - L86 LSW - RPK

Sniper Rifles

Intervention - Remington 700 - Dragunov SVU - AWS - BFG 50
AWM - TRG-42 - Mosin Nagant - Dragunov SVDS - Hecate II
M107 - Steyr Scout - WA2000


M4A1 - G36K - M4 - L22 - SCAR PDW - AKU12 - Groza-1
AK12C - Honey Badger - SR-3M - Groza-4 - MC51SD
FAL 50.63 Para - 1858 Carbine - AK105 - Jury - KAC SRR
X95R - HK51B

Designated Marksman Rifles

MK11 - SKS - SL-8 - VSS Vintorez - MSG90 - Beowulf TCR

Battle Rifles

Beowulf ECR - SCAR-H - AK12BR - G3 - AG-3 - Henry 45-70
FAL 50.00


KSG-12 - Remington 870 - DBV12 - KS-23M - Saiga-12
Stevens DB - AA-12 - SPAS-12

Secondary Weapons Pistols

M9 - G17 - M1911 - Desert Eagle L5 - M45A1 - Five Seven
ZIP 22 - Desert Eagle XIX

Machine Pistols

G18 - 93R - TEC-9 - Micro Uzi - MP1911


MP412 REX - Mateba 6 - 1858 New Army - Redhawk 44
Judge - Executioner


Serbu Shotgun - SFG 50 - Sawed Off - Saiga-12U - Obrez

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