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B&T Swiss 40mm Grenade Launcher
By Jason M. Wong

Switzerland is well known for its exquisite time pieces, fine chocolate, and its highly professional banking practices. The firearms manufactured by the Swiss are of equal quality, bar none. Based upon the recent innovations at Brügger and Thomet, the new GL-06 may become the de facto leader in 40mm grenade launching platforms.

Basic History of the 40mm Grenade Launcher

The GL-06 heralds from a long line of 40mm predecessors. Elements of the M79, M203, and HK Model 79 grenade launchers are evident within the design of the GL-06, placing the GL-06 well within the third generation of 40mm systems. Three generations of 40mm grenade launchers? Indeed. The U.S. manufactured M79 grenade launcher was the first 40mm grenade launcher to be effectively adopted. Together with the Heckler and Koch HK69 grenade launcher, the two systems represent the first generation of 40mm grenade systems. Primarily made of steel, first generation 40mm systems tend to be heavy, are intended solely as a primary weapon, and are used exclusively as stand alone units. In addition, first generation systems cannot be mounted to a primary weapon.

Second generation 40mm systems moved away from operating solely as standalone units, becoming integrated systems that could be mounted on a primary weapon. The U.S. manufactured M203 and Heckler and Koch model HK79 are examples of second generation grenade launchers. Second generation launchers are still primarily made of steel and aluminum, with the inclusion of some plastics and polymers within non-key parts. The types of ammunition for second generation 40mm systems are usually limited to a maximum of 5.25 inches in length - the length of an M583 parachute flare. Ammunition longer than 5.25 inches in length typically cannot be used within second generation 40mm systems.

Third generation 40mm systems incorporated new materials, with the replacement of steel and aluminum for polymers and plastics. In addition, several third generation grenade launchers can be used in a dual capacity role - either mounted to a primary weapon, or used as a stand alone unit. Within third generation 40mm systems, the maximum length of the intended ammunition is no longer an issue, due to the chamber and/or barrel design. Finally, optical sights are generally incorporated into the system, replacing leaf sights or other iron sighting systems. The Brügger and Thomet GL-06 is an excellent example of a third generation 40mm system.

Use of the B&T GL-06

Intended as a secondary weapon, the GL-06 cannot be mounted to a primary weapon. In this regard, use of the GL-06 is necessarily limited to specific functions and missions. While this may appear to be a negative aspect to the design, the lack of mounting hardware forces the user to contemplate the requirements of the mission. With the ever increasing real estate for mounting options on battle rifles, weight considerations must be contemplated; if a 40mm system is not required, it need not be mounted and carried on the primary weapon. Unlike the mounted M203, the GL-06 requires the user to actively utilize the system as a secondary weapon, forcing the user to determine whether a 40mm system is required for the intended mission. Although designed as a secondary weapon, the GL-06 is capable of serving in a multitude of roles, whether as a platform for less-lethal munitions, or as a support weapon in land warfare.

Operation and Design

The GL-06 is a single shot, break action system. Like most 40mm systems, the GL-06 is designed with a double-action only trigger. This means that the trigger pull requires deliberate and conscious thought to engage - an important quality when firing high explosive rounds down range. The internal hammer also serves double duty as the firing pin, similar to the design of the Heckler and Koch Model 69 system. As a break action weapon, the system’s design heralds back to the original 40mm system - the M79 grenade launcher. Unlike the M79, the GL-06 is lightweight, offers better iron sights, the ability to mount optional optical sights, and provides features that were never considered when the M79 was produced.

Unlike the M79, the GL-06 will accept any type 40x46mm ammunition. This is an important feature due to recent advances in 40mm rounds with integrated camera and data transmission capabilities, advances in 40mm medium velocity rounds capable of firing 800 meters, and advances in the development of alternate payload 40x46mm rounds.

The GL-06 rear sight features a ghost-ring sight for fast and accurate target acquisition, combined with a protected front blade sight. The safety is a simple push through design that locks the hammer from forward movement, and prevents any accidental discharges. The system is fully ambidextrous, capable of left or right handed fire without modification. In addition, the system features both left and right side sling attachment points for added flexibility. Brügger and Thomet is known for its innovative aftermarket stocks, allowing various submachine guns to be used with a variety of equipment. The same stock designs are available for the GL-06.

When the barrel is closed against the receiver, two locking lugs lock the barrel to the receiver. The barrel release latch is located in the forward edge of the trigger guard, and rotates upward to unlock the barrel. Although this may seem unwieldy, the wide trigger guard provides sufficient clearance for easy operation with heavy gloves, without the user feeling restricted within the trigger guard. When unlocked, the two locking bars are released, unlocking the barrel. A spring between the barrel and the receiver provides tension, allowing the barrel to open under its own power. The user need not physically raise or lift the barrel to expose the breach.

In response to the needs of end users, a Mil-Std 1913 Picatinny rail has been incorporated onto the top of the barrel, while three Mil-Std 1913 Picatinny rails adorn the 3, 6, and 9 o’clock positions on the receiver. Unlike prior generation 40mm systems, the prolific use of Picatinny rails allow the user to mount optical sights, a forward grip, or illumination tools to the system. The ability to mount an optical sight alone presents an increase in accuracy from prior 40mm systems, and gives the user an easier sight picture to define when in a combat or stressful environment.

The allowance to add accessories adds further value to the system when faced with less lethal and crowd scenarios. The ability to effectively make a show of force may act as a deterrent and prevent the need to actually use force. The capability to mount any variety of accessories to the launcher gives the end user flexibility to configure the GL-06 to the intended mission.

Off to the Range

The GL-06 is a robust and hardy system that proved to be ergonomically simple and comfortable to shoot. Unlike earlier 40mm designs, the lack of large external metal parts ensured that the weapon could be effectively fired within the desert environment, and without the fear of being burned by exposed metal components. In comparison, other 40mm systems were almost impossible to fire effectively within the desert environment due to the need to place the shooter’s face directly on an exposed (and hot) metal receiver. This was not an issue with the GL-06.

The test unit was not outfitted with an optical sight. According to Brügger and Thomet, the iron sights are zeroed to 25 meters for use with standard 40mm ammunition. When used as an emergency backup sight for high explosive grenades at close range, Brügger and Thomet offered the guidelines in the included to adjust point of aim.

In practical use, the guidelines were effective. After firing several rounds, estimating both range and point of aim became intuitive and easy to achieve. This is not to mean that all rounds fell on target - to the contrary. However, firing the weapon and getting the round “close enough” was easily accomplished with experience and practice.

Real World Use and Experience

In 2008, the GL-06 chosen by the French National Police for use as a less-lethal 40mm weapons system. Karl Brügger, Managing Director of Brügger & Thomet AG commented, “B&T is very happy to be able to assist the French National Police in upgrading their public order capabilities. The addition of the GL-06 Less Lethal Launcher will lead to increased order and stability in France as well as a reduction of injuries to policemen and violent subjects. B&T will continue to focus on close cooperation with all police and military partners with this product and all the other products we produce. We are excited to work the French National Police and feel confident that the system will fill an important niche in their missions to maintain order and public safety.”

Brügger and Thomet was founded in 1990 to produce suppressors for the Swiss domestic market. Ongoing research and development by Brügger and Thomet has demonstrated that the company is highly capable of designing and building top quality products for the international market. The B&T GL-06 is no exception.

GL-06 Specifications

Designation: GL-06
Manufacturer: Brügger & Thomet AG, Switzerland
Product ID:
   BT-31000 black without access safety BT-
   BT-31000-2 yellow (RAL 1021) without access safety
   BT-31000-3 yellow (RAL 1021) with access safety
Caliber: 40 x 46 mm
System: Break-down single shot, double action only
Barrel length [mm]: 280
Twist rate [mm per turn]: 1200
Rifling: 12 grooves, right hand
Overall length [mm]: 590 (stock unfolded)
385 (stock folded) Overall width [mm]:
60 (stock unfolded) 95 (stock folded)
Overall height [mm]: 200
Weight [kg]: 2.05
Sights: Ghost ring iron sights (sight radius 339 mm), adj. in windage
Interfaces: 4 rails Picatinny Mil-Std 1913
Standard supply: Weapon complete with siderails, rail covers and carrying sling


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