M320
The M320 is a single-shot 40×46mm low-velocity grenade launcher that mounts under a service rifle or operates as a standalone weapon with a collapsible stock, adopted by the U.S. Army in 2009 to replace the M203.
The U.S. military's successor to the M203 — a side-loading, break-action 40×46mm grenade launcher that can attach to an M16/M4 rifle or be used independently with a collapsible stock.
Overview
The M320 Grenade Launcher Module is a single-shot, break-action launcher chambered for the 40×46mm low-velocity grenade family. It can be fitted under the barrel of an M16 series rifle (M320) or the M4 carbine (M320A1), or detached and used as a standalone weapon with an extending stock and its own sighting system. The weapon replaces the venerable M203 in U.S. Army and Marine Corps service, restoring the stand-alone capability lost when the M79 gave way to the under-barrel configuration, while adding a side-loading breech that accepts cartridges too long for the earlier design.
Development
The M320 is derived from Heckler & Koch's AG36 (Armee-Gewehr 36) and the later AG-C/EGLM family, which were developed to provide a modern, side-loading alternative to the M203. The U.S. Army selected the system in a competitive program and fielded it as the M320 beginning in 2009, making it the first new under-barrel grenade launcher adopted since the Vietnam era, according to Wikipedia. The Marine Corps subsequently adopted the M320A1 variant for the M4, with full operational capability declared in 2017.
Design & capabilities
The launcher uses a side-swinging, break-action breech that allows the barrel to be opened to the left, enabling the use of cartridges longer than the M203 could chamber, such as certain non-lethal and extended-range rounds. It operates with a double-action trigger mechanism and a manual safety. When detached from the host rifle, the launcher receives an adjustable shoulder stock and a standalone grip module, turning it into an independent weapon. Sighting is provided by a laser-ranging day/night sight system developed in collaboration with Wilcox Industries. The launcher’s ambidextrous design, combined with its ability to function in either role, gives the grenadier greater flexibility than the fixed-under-barrel M203. The full 40×46mm low-velocity ammunition family – high-explosive, HEDP, smoke, illumination, non-lethal – is compatible, and the launcher is described by Heckler & Koch as part of the company’s modular 40mm system.
Variants
- M320 – designed to mount on M16-pattern rifles; the original U.S. Army variant.
- M320A1 – modified to fit the shorter M4 carbine, and the variant adopted by the U.S. Marine Corps.
Combat record / operational use
The M320 entered U.S. Army service in 2009 and has been carried in every major American ground deployment since, including the closing years of the Iraq War and the war in Afghanistan, where it gradually replaced the M203, as noted by Wikipedia. British forces adopted a derivative as the L17A2, and similar Heckler & Koch 40mm launchers are in service with Germany and other NATO nations. The launcher’s combat profile in open sources remains tied to its role as a standard-issue squad grenade-launcher; no unique operational incidents are publicly documented.
Advantages
- Side-loading breech accepts cartridges too long for the M203, including extended-range and specialist rounds.
- Dual-role capability (under-barrel or standalone) restores flexibility lost when the stand-alone M79 was retired.
- Double-action trigger improves rate of fire and safety compared with single-action designs.
- Compatible with the full NATO 40×46mm low-velocity family.
- Modern laser-ranging sight options increase first-round hit probability.
Drawbacks / limitations
- When mounted, the launcher is bulkier and heavier than the M203 on the same weapon.
- The side-opening breech may be awkward for left-handed shooters when used under-barrel.
- Standalone configuration adds weight and stowed-length beyond a simple under-barrel setup.
- The system remains a single-shot weapon; a grenadier must manually reload each round.
Counterparts
Outlook
The M320 is the current U.S. Army and Marine Corps standard under-barrel grenade launcher and is expected to remain in that role for the foreseeable future. Integration of advanced fire-control sights and non-lethal munitions continues, while some specialist units and legacy formations may retain the M203 for lower weight or cost. The weapon is a mature, field-proven system with no announced successor.
Key specifications
| Spec | Value |
|---|---|
| Crew | 1 |
| Combat weight | ~1.5–1.62 kg (launcher); ~2.2 kg with stock |
| Length / width / height | Length ~350 mm (collapsed) / ~525 mm (stock extended); other dimensions not publicly established |
| Main armament | 40×46mm low-velocity grenade launcher |
| Secondary armament | None |
| Armor & protection | None |
| Engine & power | Not applicable (manually operated) |
| Power-to-weight | Not applicable |
| Road / cross-country speed | Dependent on operator |
| Operational range | ~350 m effective; ~400 m maximum |
Sources
- Wikipedia — M320 Grenade Launcher Module. https://en.wikipedia.org/wiki/M320_Grenade_Launcher_Module
- Heckler & Koch — GLM / 40mm systems. https://www.heckler-koch.com/en/Products/Military%20and%20Law%20Enforcement/40%20mm%20systems/GLM
- IMFDB — Heckler & Koch AG grenade launcher series. https://www.imfdb.org/wiki/Heckler_%26_Koch_AG_grenade_launcher_series
- Wilcox Industries — GSS: Wilcox & U.S. Army Collaboration. https://wilcoxind.com/approach/gss-wilcox-army-collaboration