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Terminal.png This article, M397 Individual Automatic Rifle, was written by Ajax 013. Please do not edit this fiction without the writer's permission.
"People complain about the lack of volume of fire from one of these things. But I tell you, when that suppressive fire is repeatedly hitting targets out to 700 metres at fully automatic, are you complaining?"
―Anonymous Army Serviceman

M397 IAR
Production information

Misriah Armoury


Individual Automatic Rifle

Technical specifications
  • Weight
    • 3.8 kilograms (unloaded)
    • 4.2 kilograms (loaded)
  • Length
    • Overall:1090mm
    • Barrel Length:26 Inches
Magazine Size

32/64/96 round magazines

Fire Mode
  • Semi-Automatic
  • Automatic
Ammunition Type

7.62x51mm NATO


Short stroke gas operated open bolt

Rate of Fire

750-900 rounds per minute


720 metres (1000 with scope)


1410 metres


Necros War




The M397 Individual Automatic Rifle is a UNSC rifle, designed for accurate, long range suppressing fire. It is typically used during conflicts and engagements when fire fights occur at longer than standard ranges. Its design is based on a heavily modified M395 Designated Marskman Rifle, since removed from service.


The M397 IAR is typically issued to automatic riflemen during operations when it is predicted the majority of engagements will occur at long range. While it will never replace the M122 LMG on deployment, it will augment and supplement it. Without a scope, it is accurate to 700 meters, an can maintain accuracy even under continuous fire. While it lacks the volume of fire that the M122 and M739C possesses, it is much more accurate out to range, aiming to suppress the enemy through accuracy rather than weight of fire. It is also smaller and lighter than these weapons.


The M397 carries the majority of outer and inner hard ware that its predecessor carried. It features a short stroke, gas operated system, firing from an open bolt, a ambidextrous magazine release, ambidextrous fire selector with safe, semi and automatic firing settings, a single Misriah rail running the length of the upper receiver, and one on the left and right side of it, as well as a rail underneath the barrel. The components It is fitted with a heavy, 26 inch, high quality cold hammer forged steel-chrome barrel with a moulded carbon fibre lining. This design reduce heat increase caused by continued rapid fire as well as fouling and increases service life. This barrel is entirely free floating, and has a heavy 1:7 twist, and features a quick detach capability so it can be swapped out once the barrel becomes to hot to fire accurately. The majority of the gun is constructed from polymers and composites, to keep the weight down, though there are some titanium alloy components. It features a recoiling bolt that travels downwards rather than backwards, reducing backwards recoil and creating a more comfortable weapon for continuous fire. It is usually fitted with a flash hider designed to reduce recoil, though can be exchanged for a suppressor or a different model.

It can be fitted with the standard magazine from a MA6A rifle, though it is usually issued with the larger 64 or 96 round magazines. The M397 is also usually deployed with a scope, usually a 4 times optical sight, and always deployed with a bipod, though may also be deployed with/or a foregrip.

The M397 can lay bursts of suppressing fire to incredibly high ranges, and has greatly reduced weight over average machine guns, which gives it a small advantage. It is rarely deployed in urban scenarios, but in conflicts where engagement ranges are expected to continuously occur over 500 metres, it will deployed, usually on a one for one basis, with every other fireteam swapping their M122 MG for a IAR.

UNSC Comments

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

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