M320 Grenade Launcher Module

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 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.

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). 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.

Overview
The M320 has three major parts: a grenade launcher, Day/Night Sight (DNS) produced by Insight Technology, Inc and a hand held Laser Range Finder (LRF). Some of the benefits are: 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 M320 can be used in two ways. It can be attached to the M16 assault rifle and the M4 carbine, attaching under the barrel forward of the magazine, or it can be used dismounted with a stock attached as a stand alone model.
 * The Day/Night Sight allows the grenadier to effectively engage the enemy in the dark.

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.

The LRF helps eliminate range estimation errors common in shots greater than 100 meters, thus increasing first round hit probability.

The M320 has the ability to fire detached from a rifle. Soldiers have reported difficulties carrying it unmounted. The grenade launcher comes with a one-point sling, which 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 is using the "buy-try-decide" concept, which allows the Army to test the functionality of equipment without spending much time on research and development. One model was bulky and included pockets for grenades, another is more streamlined and offers less protection for the module, and the third was a mix of the two. Soldiers from the 75th Ranger Regiment were given a dozen holsters and went through standardized tests in mid May 2013. The soldiers filled out surveys after the testing. Each of the holsters had small issues that need adjusting, with none necessarily performing better than the others. The next step is to test them with an entire brigade. As of July 2013, the holsters are being evaluated by soldiers in Afghanistan. Project officials will make a recommendation to Fort Benning by the beginning of fiscal year 2014.