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M79 GL Single-Shot Reusable 40mm Grenade Launcher (1961)

Authored By Staff Writer | Last Updated: 6/11/2013

The handy, single-shot M79 40mm grenade launcher was utilized to good effect in the Vietnam War with American forces.

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During World War 2, the standard infantryman utilized thrown hand grenades and rifle grenades when clearing out suspected enemy positions. These proved viable solutions though the former was limited by the range of the throw and the latter was limited by its range when ignited off of the muzzle of a service rifle. In the early 1950s, work was being done on a dedicated grenade projecting solution. The major portion of this program produced the standardized 40x46 grenade projectile though deciding on a viable launcher concept proved elusive. The storied Springfield Armory of Springfield, Massachusetts USA had developed a serviceable prototype in the form of the "S-3" beginning in 1953. With American Army interest, the type was evolved to become the "S-5" prototype and, finally, developed into the operational-level XM79 to undergo formal evaluations into the late 1950s.

The XM79 was a break-action single-shot weapon featuring a wooden stock, integrated wooden grip and wooden forend. To this was inlaid the metalwork required of the action and the barrel which was of a simple, smooth-sided finish. The trigger unit was underslung at the action and ahead of the grip in the usual way. A forward iron sight was added at the muzzle while a more useful flip-up leaf assembly was added ahead of center for ranging. The operator need only to break the action open, insert a 40mm projectile into the breech, close the action, aim and fire. Overall weight of the loaded weapon was a handy 6.45lbs with a manageable unloaded weight of 6lbs. Overall length was 29 inches which made for a relatively compact weapon system. The barrel measured 14 inches long.

The XM79 passed the requisite trials to become the "M79" in the US military inventory. The series was adopted in late 1960 and serial production spanned from 1961 into 1971 to the tune of 350,000 examples.

The ability to evolve the infantryman into a grenadier held its advantages in that it provided ranged artillery-type fire at the squad level. However, its dedicated nature meant that the operator was issued the weapon as his primary with a sidearm pistol or bayonet as his only means of close-quarters protection, a limitation which soon became wholly apparent to observers. This led to the experimental Colt XM148 underbarrel system that was eventually abandoned. The XM148 and M79 were eventually superseded by the underbarrel M203 series in modern times.

The M79 relied on the proven 40x46mm grenade which was developed into a variety of useful warhead forms to suit specific battlefield situations. There was the standard HE (High-Explosive) type followed by a general smoke and illumination round. To this was added anti-personnel types including flechette-based rounds, buckshot projectiles and non-lethal rounds. A trained M79 grenadier could lay down an optimal rate-of-fire of approximately six rounds per minute. Each grenade exited the muzzle at 247 feet per second and was based on the US Army's called-for "High-Low Propulsion System" to ensure the recoil forces could be controlled from a weapon this small. Effective useful range was within 380 yards while a maximum range of 440 yards could be reached in ideal conditions. However, each grenade required a minimum 30 meters for the activation system in each projectile to achieve arming.

The M79 saw particularly heavy use in the Vietnam War (1955-1975) where its firepower proved a godsend to troops under the jungle canopy, on hillsides and in urban fighting. The grenade offered enough firepower to engage light-skinned vehicles and dug-in enemy forces, even those in elevated positions. The M79 could be used as a direct line-of-sight weapon or have its 40mm grenades lobbed into enemy positions as required and fired from the standing, kneeling or prone position. The system of operation itself proved rather simplistic to learn though the effective operation required a steady hand, good vision and excellent use of trajectories. While the US Army still sought a multi-shot grenade launcher solution, the M79 certainly filled the role required of it for its period in history. It could just as effectively be issued to waterborne forces such as PBR (Patrol Boat, Riverine) crews to help supplement offshore firepower and paratrooper/airborne infantry whose lives depending upon compact and portable weaponry.

However, the limitations in the M79 were apparent over time. Operators were left without a true short-to-medium range weapon in which to engage enemy infantry who fell between their grenade launcher's reach and just outside of their pistol sidearm (almost always the Colt M1911 semi-automatic pistol). The break-action, single-shot method of the M79 also meant a rather pedestrian rate-of-fire could be achieved in the heat of battle, requiring reloading between each successive shot. Regardless, the system proved highly compact in the confines of jungle warfare and transportable in the hand or over the shoulder by way of a strap.

The M79 proved a success on the world stage where its use went beyond that of the American Army. Australia, Brazil, Iran, Israel, Jordan, Kenya, Lebanon, Malaysia, Philippines, Saudi Arabia, South Korea, Spain, Taiwan, Thailand, Turkey, Vietnam and Yemen were just some of the notable operators of the type. S&T Daewoo produced the M79 under local license as the "KM79". South Africa's Milcor/Mechem have taken to revising M79s with optic sights and the shoulder stock of the R-series assault rifles/carbines.

If anything, the M79 certainly proved a major stepping stone in the American development of the underslung rifle-attached grenade launcher. While several recent experimental trial automatic weapons went on to see increased use of an integrated 20mm grenade launcher system, the move from the 40mm caliber does not appear likely. The M203, the system adopted to replace the venerable M79, has itself been replaced with the adoption of the Heckler & Koch HK M320 series for the US Army.

During its lengthy service life, the M79 was given rather colorful nicknames including "Bloop Tube", "Blooper", "Thumper" and "Thump-Gun". It remains in circulation with many key military powers in the world today (2013) and has even seen renewed use by the US Navy SEALs and other specialist forces operating in both Iraq and Afghanistan. It is also in widespread use as an anti-riot weapon the world over.

Springfield Armory had been the major brand label associated with the M79 though Action Mfg Company, Daewoo, Exotic Metal Products, Kanarr Corporation and Thompson-Ramo-Woolridge have also been involved, brining worldwide production numbers beyond the listed 350,000 US-produced units.

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Specifications for the
M79 GL
Single-Shot Reusable 40mm Grenade Launcher


Country of Origin: United States
Manufacturer: Various Contractors - USA
Initial Year of Service: 1961


Overall Length: 731mm (28.78in)
Barrel Length: 356.00mm (14.02in)
Weight (Empty): 6.00lbs (2.72kg)


Caliber: 40x46mm
Action: Single Shot Breech Loading
Feed: 1
Muzzle Velocity: 250ft/sec (76m/sec)
Rate-of-Fire: 6 rounds per minute
Range: 1,150ft (351m; 383yds)
Sights: Flip-Up Iron; Forward Iron


Variants:
M79 - Base Series Designation


Operators:
Australia; Brazil; Cambodia; Chad; Colombia; Costa Rica; Dominican Republic; El Salvador; Eritrea; Ethiopia; Fiji; Greece; Guatemala; Haiti; Honduras; Indonesia; Iran; Ireland; Israel; Jamaica; Jordan; Kenya; Lebanon; Malaysia; Myanmar; Nicaragua; Oman; Paraguay; Philippines; Portugal; Saint Vincent and the Grenadines; Saudi Arabia; Somalia; South Korea; Spain; Taiwan; Thailand; Turkey; United States; Vietnam; Yemen