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Heckler & Koch HK GMG (GMW / GraMaWa)

Automatic Grenade Launcher (AGL) (1996)

Infantry Small Arms / The Warfighter

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Image copyright HK-USA marketing material.

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The Heckler & Koch HK GMG makes use of the high-velocity 40x53mm grenade through a repeat-fire function.

Authored By: Staff Writer | Last Edited: 12/21/2020 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.
The Heckler & Koch GMG ("GranatMaschinenWaffe" or "GraMaWa") is a 40mm automatic grenade launcher similar in form and function to the American Mk 19 series. It fires a high-velocity 40x53mm grenade in various warhead types to suit mission requirements. The high-velocity form contrasts the 40x46mm low-velocity series found in several shoulder-fired weapons. The high-velocity version is primarily reserved for vehicle-mounted guns. As such, the GMG is an oversized automatic grenade projector usually fitted to a heavy duty pintle mounting or tripod assembly.

Overall dimensions include a running length of 1,090mm with a barrel of 415mm long. The field version of the weapon consists of the 29kg gun system and 11kg tripod. The automatic nature of the weapon utilizes a recoil-based API (Advanced Primer Ignition) blowback action consistent with cannon caliber types 20mm and larger. Through the API action, the primer is ignited while the bolt is still in motion (moving forward) during which the cartridge is still being seated into the chamber. The bolt moves both forward and backward in the action, allowing for a reduced recoil force to be achieved which serves an automatic weapon such as this very well. The GMG can achieve a rate-of-fire of 350 rounds per minute and fires each grenade at a muzzle velocity of 790 feet per second out to an effective range of 1,500 meters and maximum engagement range of 2,200 meters. The GMG is fed by a 32-round disintegrating link belt usually held in an accompanying ammunition box. Feeding is through the right side of the receiver with spent casings ejected through a port on the left side. A carrying handle is fitted at the base of the barrel while additional aiming handles are present at the rear of the receiver. The barrel is capped by a long slotted muzzle brake. While fitted with standard iron sights, a reflex optical sight is also provided.

The GMG was designed by engineers at Heckler & Koch from 1992 to 1995 before seeing adoption by German Army forces in 1996. The series continues production today (2013) and is in the inventories of Canada (as the licensed-produced Rheinmetall-Canada "C16 CASW"), Finland (as the "40 KRKK 2005"), Greece, Ireland, Latvia, Lithuania, Netherlands, New Zealand, Norway, Poland, Portugal, Slovenia, the United Kingdom (as the "L134A1") and the United States (under SOCOM).


Service Year

Germany national flag graphic


Automatic Grenade Launcher (AGL)

Heckler & Koch GmbH - Germany
National flag of Canada National flag of Finland National flag of modern Germany National flag of Greece National flag of Ireland National flag of Malaysia National flag of the Netherlands National flag of New Zealand National flag of Norway National flag of Poland National flag of Portugal National flag of Slovenia National flag of the United Kingdom National flag of the United States Canada; Finland; Germany; Greece; Ireland; Latvia; Lithuania; Malaysia; Netherlands; New Zealand; Norway; Poland; Portugal; Slovenia; United Kingdom; United States
(OPERATORS list includes past, present, and future operators when applicable)
Fire Support
Capable of suppressing enemy elements at range through direct or in-direct fire.
Special Forces
Qualities of this weapon have shown its value to Special Forces elements requiring a versatile, reliable solution for the rigors of special assignments.

Overall Length
1,090 mm
42.91 in
Barrel Length
415 mm
16.34 in
Empty Wgt
104.72 lb
47.50 kg

Iron; Optional Optics.


API Blowback; Automatic

Blowback Operation
Gas pressure from the rearward movement of the ignited cartridge case provides the needed bolt movement, ejecting the spent case and stripping a fresh case from the magazine.
(Material presented above is for historical and entertainment value and should not be construed as usable for hardware restoration, maintenance, or general operation - always consult official manufacturer sources for such information)



Rounds / Feed

32-round disintegrating belt
Cartridge relative size chart
*May not represent an exhuastive list; calibers are model-specific dependent, always consult official manufacturer sources.
**Graphics not to actual size; not all cartridges may be represented visually; graphics intended for general reference only.
Max Eff.Range
5,000 ft
(1,524 m | 1,667 yd)
Muzzle Velocity
790 ft/sec
(241 m/sec)

Granatmaschinengewehr (GMW / GraMaWa) - Base Series Designation.
C16 CASW ("Close Area Suppression Weapon") - Canadian Army designation.
40 KRKK 2005 - Finnish Army designation
L134A1 - British Army designation

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