M320 Grenade Launcher Module

History

In 2004, the U.S. Army put out a call for a commercially available 40 mm grenade launcher that would outperform the M203 in reliability, ergonomics, accuracy, and safety. It had to handle all standard low-velocity 40 mm rounds while using a breech-loading design to accommodate future, longer projectiles. Heckler & Koch won the selection process in May 2005. Following a competitive bidding round managed by the Army at Picatinny Arsenal, the company received a contract in 2006 to supply the XM320.

The M320 is based on the Heckler & Koch AG36 but is not identical; its main difference is a folding foregrip placed ahead of the trigger, allowing the weapon to be used in a standalone mode. Production began in November 2008. The rollout was scheduled to start in February 2009, with 71,600 units intended to replace the M203 by 2015. The M320 was first issued in July 2009 to the 1st Brigade Combat Team of the 82nd Airborne Division at Fort Bragg.

In June 2017, Bravo Company, 2nd Combat Engineer Battalion became the first U.S. Marine Corps unit to receive the launcher. The Marines planned to distribute 7,000 launchers between 2019 and 2022. The M320A1 variant reached Initial Operational Capability with the Marine Corps in the second quarter of fiscal year 2020. As of April 2026, the Army has solicited proposals for a next-generation system to replace both the M203 and M320, called the Precision Grenadier System.

Design

The M320 grenade launcher module can operate either attached to an M16, M4 carbine, or HK416 via the picatinny rail located under the barrel ahead of the magazine, or as a standalone weapon with a stock attached. When a grenadier carries an M320 with an M4 and three dozen 40 mm grenades, the total weapon load comes to 38 pounds, or 17 kilograms. This launcher is derived from the earlier Heckler & Koch AG-C, but it incorporates Army-specific changes, including a folding foregrip and a shorter barrel to make it more compact.

Because of the shorter barrel, the sights had to be adjusted to maintain accuracy with the altered ballistics. Although the M320 was intended to be lighter than the M203, it is actually a bit heavier, and it does not need any special mounting hardware. Its breech-loading design lets the grenadier load a shell while keeping the sight aimed at the target.

The launcher weighs 3.57 pounds in its basic form and 4.8 pounds with the stock attached. The sights are positioned on the side of the launcher, which solves the issues seen with the M203’s top-mounted sight. That older design could block the rifle’s sights and required separate attachment and re-zeroing each time the launcher was put back on the rifle. The M320’s leaf sight covers ranges from 50 to 350 meters in 50-meter steps.

The M320 can also use the AN/PSQ-18A, an enhanced aiming device built for daylight, low light, and night use. It includes a built-in range scale, an integrated aiming laser, an anti-cant indicator, and a backup iron sight. However, troops did not like this sight because it was too heavy and bulky.