M320 Grenade Launcher Module

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M320 Grenade Launcher Module
PEO M320 Grenade Launcher.jpg
Standalone M320 with detachable buttstock
Type Grenade launcher
Place of origin Germany
Service history
In service 2009–present
Production history
Designed 2008
Manufacturer Heckler & Koch
Unit cost US$3,500
Produced 2008
Weight 1.5 kg (3.3 lb)
Length 350 mm (13.7 in.)
Barrel length 280 mm (11 in.)

Cartridge 40x46mm SR
Action Single shot, double action
Rate of fire 5 to 7 rounds per minute
Muzzle velocity 76 m/s
Effective firing range 150 m (point)
350 m (area)
Maximum firing range 400 m
Feed system Single shot

M320 Grenade Launcher Module (GLM) is the U.S. military's designation for a new single-shot 40 mm grenade launcher system to replace the M203[1][2] for the U.S. Army, while other services will keep using the older M203. The M320 uses the same High-Low Propulsion System as the M203.

In 2004, the U.S. Army announced a requirement for a commercial off-the-shelf 40 mm grenade launcher. It had to be more reliable, ergonomic, accurate, and safer than the M203. It had to be able to fire all 40 mm low-velocity grenades, but be loaded from the breech to accept future longer projectiles. Heckler & Koch's submission was selected in May 2005.[3]

After the U.S. Army at Picatinny Arsenal conducted a competitive bidding process for a new 40 mm grenade launching system, Heckler & Koch was awarded a contract to provide the XM320 beginning in 2006. The M320 was developed from but is not identical to the Heckler & Koch AG36 (a key distinguishing feature being the addition of a folding foregrip ahead of the trigger for use when the weapon is in stand-alone configuration, a feature the AG36 lacks).[4] The M320 entered production in November 2008.

The unit was officially fielded in July 2009 at Fort Bragg by the 1st Brigade Combat Team, 82nd Airborne Division.[5]


The M320 has three major parts: a grenade launcher with rifled barrel, Day/Night Sight (DNS) produced by Insight Technology, Inc and a hand held Laser Range Finder (LRF). Some of the benefits are:

  • The Day/Night Sight allows the grenadier to effectively engage the enemy in the dark.
The M320 with electronic targeting system mounted on the M4 carbine.
Hungarian AK-63MF with M320 Grenade Launcher

The M320 is based on the earlier Heckler & Koch AG-C, but with some Army-specific modifications. It includes a folding foregrip and shorter barrel for a more compact package. The sights had to be reconfigured to shoot accurately with the slightly different ballistics from the shorter barrel length. The system is lighter than the M203 and does not require specific mounting hardware. Breech loading allows the grenadier to load a shell while keeping the sight on target.[3]

The sights on the M320 are located to the side of the launcher. This avoids the problems that the M203 had with its sight design. The M203's sights were mounted on top of the launcher and could interfere with the rifle's sights and they had to be attached separately. This meant two separate operations had to be performed when adding the grenade launcher to the weapon, and since the sights were not integral to the M203, they had to be re-zeroed every time the launcher was reattached to the rifle. The LRF helps eliminate range estimation errors common in shots greater than 100 meters, thus increasing first round hit probability.

The M320 can fire all NATO high-explosive, smoke, and illumination grenades. Its breech opens to the side, allowing it to fire a variety of newer rounds which are longer, in particular certain non-lethal rounds, such as Federal Laboratories' "exact impact" (brand name) non-lethal sponge batons or sponge grenades.

The M320 operates in double-action mode, with an ambidextrous safety. In case of misfire, the M320 operator merely has to pull the trigger again. The M203 used a single-action mode, which cocks the weapon as the barrel is opened. The M203 operator has to open the barrel by unlocking it and pushing forward to cock the weapon and then re-close the barrel, then pull the trigger again. The problem with this is that in opening the barrel, the grenade is designed to eject and the operator must ensure that it does not fall to the ground.

A U.S. Army soldier training with an M320 mounted on an M4 carbine

The M320 has the ability to fire detached from a rifle. Soldiers have reported difficulties carrying it unmounted, as its one-point sling does not hold it securely. Carrying by the sling would cause it to bounce around and sometimes be dragged through dirt. Soldiers wanted to carry the M320 in a holster to provide protection, rather than just putting it in their rucksack. The Natick Soldier Systems Center began the M320GL Holster Soldier Enhancement Program (SEP) in November 2012. Three commercial vendors produced 167 holsters each. The SEP used the "buy-try-decide" concept, which allows the Army to test the functionality of equipment without spending much time on research and development. Soldiers from the 75th Ranger Regiment were given a dozen holsters and went through standardized tests in mid-May 2013, after which they filled out surveys. The next step was to test them with an entire brigade. As of July 2013, the holsters were being evaluated by soldiers in Afghanistan. Project officials were to make a recommendation to Fort Benning by the beginning of fiscal year 2014.[6]

The U.S. Army ARDEC began development of a 40 mm airburst fuse in 2011 to improve the ability of grenade launchers like the M320 to engage targets in defilade. Called Small Arms Grenade Munitions (SAGM), they double the lethality of the standard M433 grenade round by adding a small "smart" fuse sensor that detonates in the air to hit targets in cover or behind obstacles. The airburst function is similar to the XM25 CDTE, which has an onboard laser system to determine the distance to the target, but SAGM is considered complementary to the XM25 rather than competing against it, as the XM25 provides direct fire while the M320 fires indirectly. Engineers integrated sensors and logic devices to scan and filter the environment and then autonomously airburst the fuse without needing to be told to by the firer, thereby not requiring the soldier to carry extra weapon accessories. SAGM enables soldiers to accurately incapacitate personnel targets in defilade at ranges between 50 to 500 meters. The round is engineered with three firing modes: airburst, point detonation, and self-destruct. A successful demonstration occurred in November 2013.[7] Although the SAGM sensor does not need a laser rangefinder or any pre-fire programming sequence, it does require some skill by the user to aim and fire the round correctly so that it can detect the wall or obstruction to detonate in the air. The SAGM is to undergo evaluation in July 2015 and, if successful, it will transition into an official Army program of record by the end of the year.[8]

The weapon's introduction is not without criticism. The pistol grip tends to catch on things and the trigger tends to make the weapon shake in the hands of operators.[9] One downside of the weapon includes its increased overall weight; new features, such as sights and laser rangefinders, increase the weapon's weight to 5 lbs. One soldier in Afghanistan reported "In Afghanistan we leave the 320s behind, worthless, too heavy/bulky and unreliable. Bring back the M203". Another critique of the weapon is cost. At $3,500 per unit, the M320 is three times the price of its M203 predecessor.[10] Given this, the United States Marine Corps, Air Force, Coast Guard, and Navy will continue to use the older M203 and new ones continue to remain in production. One of the reasons for the expense difference is competitive. Only Heckler & Koch manufacture the M320. Multiple manufacturers including Colt, Lewis Machine & Tool and Airtronic produce the M203.

See also[edit]


 This article incorporates public domain material from websites or documents of the United States Army.

External links[edit]