M320 40mm Grenade Launcher Module (GLM)

As with other Grenade Launchers, the M320 40mm weapon is intended to bridge the gap between hand grenades and indirect fire assets. The M320/M320A1 Grenade Launcher serves the same function as the decades old M203/M203A1 Grenade Launcher but with many improvements.

On 1 July 2009, Soldiers of the 82nd Airborne Division received the first fielding of the M320 Grenade Launcher (and began the process of training with the weapon for combat deployments in Iraq and Afghanistan.

M320 Grenade Launcher used as a stand-alone weapon, 2009.
M320 Grenade Launcher used as a stand-alone weapon, 2009.

Today in WW II: 10 Dec 1941 General Masaharu Homma lands Japanese forces on the Philippine Islands.   

M320 40mm Grenade Launcher Module (GLM)

Under the supervision of SSGT Joseph Foti, PFC Jessica Cooke, 82nd Airborne Division, fires a 40mm training round from an M320 Grenade Launcher, at the range, Fort Bragg, NC, 1 July 2009
Under the supervision of SSGT Joseph Foti, PFC Jessica Cooke, 82nd Airborne Division, fires a 40mm training round from an M320 Grenade Launcher, at the range, Fort Bragg, NC, 1 July 2009.

In 1966 the PM-Individual Weapons, Picatinny, NJ, received requirements for an improved version of the Vietnam-era M203 Grenade Launcher. While the M203 was a successful grenade launcher, in use since 1969, it had drawbacks and limitations. Based on the requirements, a 2005 contract with Heckler & Koch for an existing GLM, and further development, the M320/M320A1 Grenade Launcher Module (GLM) for the M16 rifles and M4 Carbines was fielded in 2009. Like the M203, the M320 attaches under the barrel of the rifle or carbine, but the M320 can also convert to a stand-alone weapon, resembling a modern M79 Grenade Launcher.

Improvements in the sights on the M320 40mm Grenade Launcher are significant as the remedy to the shortcomings of the sights on the M203. The M320 integral day/night sighting system is located on the side of the launcher, a position that reduces interference with rifle and carbine sights, makes attaching the launcher a single operation, and eliminates the need to re-zero after reattaching to a weapon. The new sights provide targeting capability during day and night conditions out to the maximum effective range.

Other advantages of the M320 include:

  • The M320 barrel opens to the side, allowing for an unrestricted breech, enabling faster loading and the firing of all standard US 40mm low-velocity ammunition as well as longer-than standard ammunition such as non-lethal rounds.
  • The M320 is safer, due to its double-action trigger and ambidextrous safety. After a misfire, the operator can just pull the trigger a second time.
  • The M320 is more accurate at night than day, thanks to a laser rangefinder and infrared laser pointer fielded with each M320 to improve first-round hit probability.
  • The new pistol grip design eliminates the need to use the magazine as a hand grip.
  • The M320 is more versatile, with its ability to mount on a host rifle/carbine or be fired as a standalone weapon.
  • Time needed to attach the M320 to a rifle or carbine has been reduced to less than five minutes.
  • The M320 uses advanced composite materials, lightweight with improved durability.

M320 Grenade Launcher Ammunition

The M320 fires a range of low velocity 40mm cartridges, the same cartridges used with M79 and M203 grenade launchers. Examples include the High Explosive Dual Purpose (HEDP) 40mm rounds and an array of less-than-lethal munitions, including CN/CS/OC tear gas rounds, smoke, non-lethal projectiles, signal (eg Star Parachute) and practice rounds (blue upper case). See the Olive-Drab.com page on 40mm Grenade Cartridges for more information.

M320 40mm Grenade Launcher Characteristics

SGT Cameron Channell, 82nd Airborne Division, fires a 40mm training round from an M320 Grenade Launcher, at the range, Fort Bragg, NC, 1 July 2009
SGT Cameron Channell, 82nd Airborne Division, fires a 40mm training round from an M320 Grenade Launcher, at the range, Fort Bragg, NC, 1 July 2009.

Weight 3.3 lb (1.5 kg)
Overall Length 13.7 in. (350 mm)
Barrel Length 11 in. (280 mm)
Max Effective Range, Area Target Approximately 1310 feet (400 meters)
Max Effective Range, Point Target Approximately 490 feet (150 meters)
Rate of Fire 5 to 7 rounds per minute

The M320 Grenade Launcher mounts on the M16 family of rifles while the M320A1 mounts on the M4 Carbine family.

The M320 Grenade Launcher is made by Heckler & Koch, baed on the H&K model AG36 grenade launcher. Over the next few years after 2009, the US military will purchase more than 71,000 M320/M320A1 GLMs at a unit cost of about $3,500 according to news reports.

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