HomeWeaponsGrenade launcherM320 Grenade Launcher Module

M320 Grenade Launcher Module

M320 Grenade Launcher Module is a next-generation single-shot 40 mm grenade launcher designated to replace the M203 for the US Army. M320 comes as a standalone system that can be mounted to the bottom of an M4/M16. It also uses the exact High-Low Propulsion System as its predecessor.


M320 is a standalone grenade launcher that features a breach that slides to the left or right side of the weapon. Its configured to be loaded from the right side of the factory. This allows longer cartridges to be used. It also features a foregrip, making it easier to use separate from a rifle. The main reason the M203 is being pushed out of service is the PIKE 40 mm round. The Army concluded that too many changes had to be made to the current M203 Design to tender is capable of firing a PIKE 40MM Munition.

M320 Grenade Launcher Module (GLM) standalone
M320 Grenade Launcher Module (GLM) (Photo: XY)


In 2004, the US military decided to step up to develop a new grenade launcher to replace the old M203 that had been in use for decades. The new grenade launcher had to have better standards in reliability, ergonomics, accuracy, and safety than the previous model. 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.

Heckler & Koch unveiled the prototype of a new 40 mm grenade launching system in 2006. Heckler & Koch was awarded a contract after the US Army at Picatinny Arsenal conducted a competitive bidding process. The new model was designated as XM320. Despite being developed from the Heckler & Koch AG36, it was not identical.

A key distinguishing feature is the addition of a folding foregrip ahead of the trigger for use when the weapon is in a stand-alone configuration, a feature the AG36 lacks. The M320 entered production in November 2008.

Soldier shot from M320 Grenade Launcher Module (GLM)
Soldier shot from new grenade launcher (Photo: XY))

The first batch of 71,600 M320s was planned to be delivered in February 2009, but it was postponed. In July 2009, 1st Brigade Combat Team, 82nd Airborne Division officially fielded the first M320 GLM, while Bravo Company, 2nd Combat Engineer Battalion, became the first US Marine Corps unit to be issued the GLMs. Around 7,000 M320s will be given to Marines between 2019 and 2022.


The M320 has a double-action trigger instead of the M203’s single-action trigger. If the grenade fails to fire, you don’t have to re-cock as you do on the M203. You squeeze the trigger again. It also has ambidextrous safety. The M320 has its drawbacks, like the slightly heavier weight, relative fragility, and short stock, but it’s a direct improvement from the M203. The M320 is mainly phased out older versions, while other services initially kept using the older M203; even some NATO countries still have M79 grenade launchers in their inventory.

The sights are integral to the unit, unlike those of the M203, and don’t need to be re-zeroed every time. It also uses a laser to determine the range, which makes accurate landing shots at a distance much more manageable.

M16A2 rifle equipped with an M203 grenade launcher
M16A2 rifle equipped with an M203 grenade launcher (Photo: XY)

The M320 grenade launcher can be used in two ways mentioned above. First, it can be attached to the rifle (M16, CAR-15, M4 Carbine, HK416, or other types of rifle), under the barrel forward of the magazine, or it can be used dismounted with a stock attached as a stand-alone model.

The operator carrying an M320 under the barrel (for example, M4) and three dozen 40 mm grenades will have a total weapon load of 17 kg (38 lb). It s supposedly more accurate than M203 and comes standard with a day/night sight. The day/night sight is pretty great, but the US Marines have shown that it can be attached to and used with the M203 mounted to an M4/M16.

User experience

Overall the M320 is a better system than the M203. Especially once you become used to it, and now most soldiers haven’t used the M203, so they start on the M320. I’m just not a big fan of the weight and all the extra stuff that comes with it. The day/night sight is excellent, but the other gadgets and functions aren’t useful in most combat scenarios to warrant the extra weight.


So far, two variants have been produced:

  • M320
  • M320A1

Technical specifications

Country of origin:United States, Germany
Manufacturer:Heckler & Koch
Entered service:2009
Action:single shot, double-action
Caliber:40 mm
Cartridge:40 x 46 mm SR
Weight (empty):1.5 kg (3.3 lb)
Length:350 mm
Barrel length:280 mm
Muzzle velocity:76 m/s
Cyclic rate of fire:7 rpm
Practical rate of fire:5 rpm
Magazine capacity:single round
Sighting range:250 m
Range of effective fire (grenades):150 m (point); 350 m (area);
Maximum range (grenades):400 m
Eric Sof
Eric Sofhttps://special-ops.org
Eric Sof holds a master's degree in Political Science, specializing in International Peacekeeping Studies. He has over a decade of experience as a former member of an elite counterterrorism unit. Additionally, he is a firearms instructor and currently serves as a member of the SWAT unit.


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