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Terminal.png This article, M122 Light Machine Gun, was written by Ajax 013. Please do not edit this fiction without the writer's permission.
"You could take a crap in the mechanism, bury it in the desert, dig it up a month later, tap out the crud and it it would still fire first time!"
―Anonymous Marine

M122 LMG
Production information

Light Machine Gun

Technical specifications
  • Barrel
    • 584 mm
  • Weight
    • 5.6 kilograms
  • Length
    • 840 mm
Magazine Size
  • 72 round 'fast' drum
  • 150 round 'heavy' drum
Fire Mode
  • Automatic
  • Burst
Ammunition Type

7.62x51mm M83 AP



Rate of Fire

750 rounds per minute


670 metres (890 meters with scope)


1080 meters


Necros War




The M122 Light Machine Gun is the UNSC's standard Light Machine Gun, giving squad based units a relatively light and adaptable light support weapon. This allows squad based units to produce triple their normal amount of firepower against infantry targets. The weapon features a light but tough polymer body with heat-resistant metal alloy components and microprocessor driven thermal transfer system, utilising a series of doppler cooling systems. The M122 requires neither mid-battle barrel changes nor maintenance, allowing for rapid, uninterrupted fire. With optional retractable bipod, the M122 is most accurate when fired from the prone position. The weapon is designed for ease of carrying, with a carrying handle on the butt and a flip up carrying handle on the receiver, allowing ease of transport and steady firing from the hip.


The primary function is that of a Light Support Weapon or Squad Automatic Weapon, providing highly accurate covering or automatic fire for a unit, giving them a adaptable and mobile base of fire. The weapon is primarily used amongst the UNSC Infantry Regiments where its light weight and small size compared to the General Purpose Machine Gun make it preferred.


The M122 with a nanotech polymer bag over the drum, which can be fitted to any drum fed weapon.

The M122 is gas operated, artificially cooled and magazine fed weapon. The weapon is gas operated, utilizing short-stroke piston gas system, located below the barrel. The barrel is locked using rotary bolt with 7 radial lugs. When fired, the bolt travels down the receiver rather than backwards to absorb recoil and direct it away from the shooter. It fires from an open bolt position, the bolt containing both a spring extractor and a casing ejector. The weapon's non-reciprocating cocking handle is located on the left side of the receiver and moves to the the forward position during firing. The weapon's low recoil stems from the constant recoil principle. The design allows the bolt carrier group to move all the way back without ever impacting the rear, instead stopping gradually along the axis of movement against the resistance of the return springs. It is fed from detachable magazines only, using either a large clear polymer drum magazine or a alternate feed of a MA6A magazine. Drum magazines are made mostly from plastic, with translucent wall which permits easy check of available ammunition. The weapon features a ambidextrous cartridge extractor, being able to eject the empty casings to the left or right via locking the dust flap on one side, though both can be opened. Firing controls include a pistol grip and a conventional rifle-type trigger grouping, with ambidextrous safety and fire selector levers located at either side of receiver, above the pistol grip. The M122 fires from open bolt only, in semi-automatic or full automatic modes. It has fully adjustable and removable day/night iron sights.

The barrel is made from high quality cold hammer forged steel-chrome barrel with a moulded carbon fibre lining, giving it unparalleled heat resistance and corrosion resistance. The free floating fluted rifled barrel, with a one in seven twist requires neither changing or replacement, its only real problem is the chance that the heat inside the barrel could overheat the magazine and cook it off. To help with that, the bolt is also coated in carbon fibre materials and is protected by a lightweight doppler cooling bank. The Doppler cooling bank captures heat coming off the barrel and breech and cools it via the doppler cooling effect, keeping the weapon comfortably close to room temperature. During cold weather this is reversed, stopping it from freezing over.

The magazine uses magnetic plate induction to feed the ammunition gently into the weapon. The magazines is made of lightweight Polymers with a translucent join, allowing off hand checks of ammunition. However, it can be fitted with a soft canvas overall.

The cooling system is made up of three Doppler Shift cooling banks, controlled by a central computer unit. These capture heat coming from the barrel and bolt and cool it via the doppler shift, allowing the gun to stay cool, even under constant operation. There is a cooling bank on each side of the barrel and one on the breech. The Doppler Cooling banks are made up of an array of tiny LASERs that are arranged in opposite directions. As excited atoms and molecules enter the cooling bank, they gain photons from the laser they are moving away from, via the doppler effect. These atoms then slow to a crawl, due to the cancelling effects of the gained photons and are subsequently chilled. As the barrel continues to heat up, due to thermodynamics, the heat will move from a place of high temperature to a place of low temperature, constantly cooling the weapon until equilibrium is made. As the weapon cools down, the opposite becomes true, with the molecules within the bank moving to warm up the weapon as it drifts below equilibrium. The banks are powered by the anti-recoil systems, by thermal absorbing energy circuits and in the case of extreme colds, an external battery pack, about the size of a chatter pad. These cooling systems are controlled by a central CPU, which observes the warmest or coldest elements of the weapon and attempts to regulate this.

UNSC Comments

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"Four years of fighting the Remnant and Necros and I have never changed the barrel on mine. Never."

"While I was at the Marianus siege I ran outta box rounds during the third day of wave infantry attacks, so I started inserting MA6A magazines. Sure, I was out in a flash but they still did the job. "

"It's not as relentless as the Gimpy, but its certainly a lot more dependable."

Individual and Crew Served Weaponry of the UNSCDF


M6L Personal Defence Weapon System | M57 Pistol | M98 Compact | M19 Modular Pistol

Submachine Guns

M20A Submachine Gun | M12 Special Operations Carbine | M8Z Submachine Gun

Assault Rifles, Carbines, and Battle Rifles

MA6A Individual Combat Weapon System | M2A Carbine | M81 Special Purpose Carbine | M55C Enhanced Battle Rifle

Designated Marksman Rifles

M396 Designated Marksman Rifle | M97 Special Purpose Rifle | M113 Special Purpose Rifle

Machine Guns

M397 Individual Automatic Rifle | M739C Squad Automatic Weapon | M122 Light Machine Gun | M247B2 General Purpose Machine Gun | M247H2 Heavy Machine Gun | AIE-486K1 Heavy Machine Gun | M343A3 Heavy Machine Gun | M780 Special Purpose Machine Gun

Sniper Rifles

M22 Scout Rifle System | M818D Enhanced Modular Sniper Rifle System | M1091 Sniper Rifle System | Sniper Rifle System 99G-S6 Anti-Materiel | M99CA1 Special Application Scoped Rifle | M133 Precision Anti-Materiel Energy Weapon System


M45F Close Assault Weapon System | M108A1 Close Assault Weapon System | M77 Extreme Close Quarters Combat System

Energy Weapons

Weapon/Anti-Vehicle Model 6B Grindell/Galilean Nonlinear Rifle | MX4 Light Support Weapon | M921 ARC

Non-Lethal Weapon

M2 Threat-Negation Device | MX9 Pulsed Energy Projectile System | M39 Long Range Tranquillizer Rifle

Missile and Rocket Launchers

M41B2 Medium Anti-Vehicle/Assault Weapon | M899 Light Anti Armour Weapon | M57 Light Multipurpose Assault Weapon | M1 Multiple Launch Rocket System | M25 Underslung Rocket Launcher

Grenade Launchers

M319N Individual Grenade Launcher | M23 Multiple Grenade Launcher | M363B RPD | M460C Automatic Grenade Launcher | M556 Counter Defilade Grenade Launcher | M24 Underslung Grenade Launcher | M26 Grenade Launcher Module


M71 Mortar | M78 Mortar | M81 Mortar


M117 Light-Weight Field Howitzer

Sentry Guns

M55 GUARD DOG Sentry Gun | M601 GARGOYLE Sentry Gun


M9 Dual Purpose/High Explosive Grenade | M2 Anti-Materiel Grenade | M70 Flash Bang Grenade | M43 Smoke Grenade

Anti-Personnel and Anti-Armour Mines

M320 Anti-Tank Mine | M341 Anti-Tank Mine | M362 Anti-Tank Mine | M121 Bounding Anti-Personnel Mine | M127 Anti-Personnel Mine

Explosive Devices

C-7 Foaming Explosive | C-13 Gertex | C-14 Plastic Explosive | C-15 Liquid Explosive | M303 Thermite Cord | M311 Detonation Cord | M382 Special Munition Attack Charge (Kinetic) | M390 Breaching Charge | M394 Clearance Charge | M404 Special Lightweight Attack Munition | M366 Demolition Charge | M376 Satchel Charge | M379 Explosive Pack