Colt IAR6940

The Colt Infantry Automatic Rifle 6940 (commonly shortened to Colt IAR or IAR6940), is a Light machine gun designed by Phil Hinckley and manufactured by American firearms manufacturer Colt.

Developed as a part of the Infantry Automatic Rifle program to "satisfy the role currently played by the FN M249 SAW in a lighter, more man-portable mode" in the United States Marine Corps, the IAR6940 eventually lost out to the M27 Infantry Automatic Rifle built by Heckler & Koch. Nevertheless, the weapon was exported internationally and has found usage in militaries around the world, notably in armies in Mexico and Singapore.

The IAR6940 is gas-operated and air‐cooled. It is fed by box magazines such as the STANAG and Drum magazines. It is chambered in 5.56×45 mm NATO and is based on the M16 rifle/M4 carbine. Similar to the CAR-15, from which it shares many fundamental features, the IAR 6940 uses a direct impingement system rather than a gas piston system and includes a large heatsink below the barrel.

Background
On March 27, 2008, the United States Marine Corps issued a Purchase Description outlining the requirements for the Infantry Automatic Rifle (IAR) to potential manufacturers. The Marines were specifically looking for designs that met precise criteria.

The primary objective of the IAR Program was to replace the M249 Squad Automatic Weapon (SAW) with a single-infantry marine-operated automatic rifle that prioritized lightweight and ease of portability to enhance dismounted maneuverability. The IAR would be a non-developmental, 5.56mm automatic rifle that would be more durable and reliable than the M249 SAW.

The Marine Corps put across a specified kit that would accompany the IAR, which were a rear aperture sight (Matech BUIS), a blank firing adapter, cleaning kit, Grip Pod, 3-point sling, an operators' manual and sufficient magazines to hold 300 rounds of 5.56×45mm NATO.

US Trials
Colt Defense was awarded two contracts for each of their entries into the program; the IAR6940 and IAR6940H. The IAR 6940 is marginally heavier than the IAR6940H at 10.1 pounds (4.58 kg) compared to the latter at 9.28 pounds (4.21 kg), with the main reason being that the IAR 6940 sported a monolithic upper receiver while the IAR6940H used a lighter Knight's Armament Handguard. Colt submitted the two variants as contenders for to the IAR program.

With the kit, both models met the desired specifications of the USMC and were able to make it to the finals of the contest. However, it ultimately lost the contest to Heckler & Koch's M27 IAR. The rifle therefore never saw widespread usage in the U.S. Military but was released to the civilian market in 2017, albeit at a very low quantity at only 200 units by the U.S. Armament Company.

Mexican Army
In 2010, the Colt IAR6940 was selected and sold to the Naval Infantry Corps of the Mexican Navy and is widely used in the ongoing drug war in Mexico.

Singapore Army
In 2023, Ministry of Singapore performed trials for the New Section Automatic Weapon (NSAW) program, which would replace the aging Ultimax 100 which has been in use for roughly 42 years. The new Light Machine Gun, the IAR6940E-SG, is a new variant of the Colt IAR that was evaluated and procured in partnership with the Defense Science and Technology Agency and has been assessed to be a suitable successor to the Ultimax 100. It is currently being introduced to the Singapore Army since April 24, 2024.

The IAR6940E-SG uses a configuration that comes with a Red dot sight, a 3× Magnifier, a Laser Aiming Device and a foregrip. The modifications allowed for increased combat effectiveness and ergonomics.

Design
The Colt Infantry Automatic Rifle 6940 is a magazine-fed light machine gun. It fires the 5.56×45 mm NATO cartridge. The rifle accepts AR-15 magazines, such as the STANAG, PMAG and Drum magazines.

As a part of the IAR Program, it was built to be lighter and more portable than the M249. It weighs 4.32 kg (9.52 lb) compared to the M249 at 7.5 kg (17 lb). With the stock extended, it is 934 mm (36.8 in) in length.

The weapon uses a closed bolt, gas operated system using direct impingement very similar to the CAR-15. The gas developed from the fired cartridge is vented directly towards the bolt, sending it rearward to cycle the action. This contributes to the weapon's lighter weight and reduces wear on parts. All military models of the IAR6940 have select-fire capabilities between semi-automatic and full automatic. The rifle's gas regulator can be adjusted depending on the ammunition or desired fire rate (from 700 to 1000 rounds per minute).

The upper receiver is a monolithic design with the upper hand guard integrated. Features include a full-length MIL-STD-1913 Picatinny rail on the top, followed by 2 shorter rails on either side of the hand guard, with venting adjacent along the top side. Other characteristics of the upper receiver are largely similar to that of the M4/M16-type rifles, like the forward assist, cartridge deflector, and ejection port cover. The IAR6490 typically comes with a Matech BUIS Rear Sight, but many configurations also include accessories such as optics and lasers.

A large heatsink is implemented on the lower hand guard, which is aimed to increases the time it takes for the firearm to cook-off under extended periods of fire. It can be replaced or equipped with grip attachments. Most configurations of the IAR6940 come with a Grip Pod (a vertical foregrip with an integrated bipod) for increased stability.

The bolt assembly is identical to the M4's, and also shares the same factory charging handle and bolt carrier group. The lower receiver of the IAR6940 is functionally similar to the M4's as well with some changes including an ambidextrous fire selector and magazine release. The rear includes a H3 Buffer Tube which supports most AR stocks but comes default with a VLTOR E-Mod stock.

The barrel is 16 inches (406.4 mm) in length. It is internally chrome-plated, with progressive 1/7 right-hand parabolic twist rifling. As a requirement for the USMC IAR Program, it has a bayonet stud for bayonet mounting and a folding front sight. It is equipped with a compensator for reduced recoil.

Variants

 * Colt Infantry Automatic Rifle 6940: The default model of the Colt IAR. It features a monolithic upper receiver, increasing stability while also slighting increasing the weight with respect to the other models. The standard configuration includes a compensator, a Matech BUIS Sight and 30 round STANAG magazines. It is used by the Mexican Navy as support weapons in the Naval Infantry Corps.
 * Colt Infantry Automatic Rifle 6940H: A variant jointly developed by Knight's Armament Company (KAC). It includes many modifications that were designed and created by KAC, such as the handguard, which weighed the weapon less than the IAR6940. The standard configuration includes a compensator, a KAC Rear Sight and 30 round STANAG magazines. The IAR6940H has since been discontinued by Colt following the conclusion of the IAR trial by the Marine Corps.
 * Colt Infantry Automatic Rifle 6940P: A prototype variant that incorporated an external piston system in place of the direct gas impingement. It was a third model designed by Phil Hinckley but was never submitted into the US Marines' IAR Program.
 * Colt Infantry Automatic Rifle 6940E-SG: A variant designed specifically for the Singapore Army. It is equipped with a red dot sight with a 3x magnifier scope as well as a multi-purpose Laser Aiming Device (LAD) capable of 4 modes, visible or infra-red (IR) laser, IR illuminator.

Users

 * 🇲🇽 Mexico
 * 🇸🇬 Singapore