M79 Grenade Launcher

The M79 grenade launcher is a single-shot, break-open, shoulder-fired weapon. It is breech-loading and fires a 40x46mm grenade. It has a protected fixed front sight and a rear leaf sight that is adjustable for windage. It was designed as a close support weapon for the infantry. Designed to close the gap between the maximum range of a hand grenade and the minimum range of a mortar, the lightweight M79 fired a 40x46mm projectile (primarily of a high-explosive fragmentation type) to a range of approximately 400 meters. It was used extensively during the Vietnam War, giving US troops the capability to engage enemy point targets to 150 meters and area targets to 350 meters. With two launchers per US Army rifle squad and a total of 85 in a US Army infantry battalion, the M79 helped to improve the capabilities of small infantry units.

The M79 has an open, fixed front sight and an open rear leaf sight that is adjustable for windage. The M79 grenade launcher was designed to fire a 40mm grenade more accurately than when fired from a rifle grenade launcher. The secret to the success of the M79 was a high-low pressure system that allowed the propellant to develop a relatively high pressure in, a high-pressure chamber, before venting gases into a low pressure chamber in the grenade cartridge case.

Rifle mounted grenade launchers could deliver fire to point and area targets up to 350 meters away from individual soldiers. The M203 and M79 grenade launchers and the Ml 19 automatic grenade launcher could all fire smoke grenades. The smoke cartridges included the M713 red smoke, M715 green smoke, and M716 yellow smoke cartridges. Soldiers used rifle mounted grenade launchers to fire smoke in order to obscure snipers, enemy fighting positions, and heavy weapon emplacements. The could provide immediate suppressive smoke to degrade enemy weapon guidance links or tracking. They could also conceal the movement of small tactical units (squad or smaller).

Introduced in 1961, the M79 had been developed as an interim system as part of attempts to develop a grenade launcher as part of other weapon system development. The first of these Project NIBLICK, had been an offshoot of Project SALVO, an attempt to a weapon utilizing a hyper-velocity dart (otherwise known as a flechette) projectile fired in rapid bursts or salvos. This would eventually morph into the Special Purpose Infantry Weapon (SPIW) program, of which a grenade launcher componet was to be a part. The M79 was intended to provide a stop-gap until the SPIW, with its grenade launcher attachment, could be perfected.

By the time the US military became formally engaged in the ground war in Vietnam in 1965, the M79 had no counterpart in the enemy's arsenal. It resembled a sawed-off shotgun and fired a spherical 40mm grenade that had a "kill radius" of 5 meters. Grooves in its barrel imparted a spiral spin to the warhead stabilizing its flight. The spiral also caused weights in the fuze mechanism to arm the fuse after about 30 meters of flight, after which the shell detonated on impact. The grenades were thus safe from accidental detonation from a bump or fall, or if struck by a bullet.

The XM148 System, a weapon designed by Colt to combine the capabilities of the M79 grenade launcher with the Ml6 rifle, was introduced in early 1967. This weapon, marketed by Colt as the CGL-4, attached to the barrel of standard M16A1 infantry rifles, giving grenadiers a more powerful back up weapon to the launcher. Grenadiers armed with the M79 had been assigned an M1911 pistol as their back up weapon. While M79 users welcomed the rifle/grenade launcher concept, it proved completely unsatisfactory under combat conditions. Users complained that the sight was prone to snagging in underbrush. The sight was difficult to use with any accuracy. The extended trigger and trigger bar were also prone to snagging, and could be bent or broken when opening or closing the rifle's receiver during/after fieldstripping. The separate cocking lever was very unpopular due to the force required to cock the weapon. Within a few months, units with the XM148 were clamoring to have their M79 reissued. The XM148 however, did serve as a proof of concept for more sucessful M203 grenade launcher.

The M203 was designed and procured as the replacement for the M79 grenade launcher. By 1969, the M79 grenade launcher was being supplanted by the M203, which like the XM148 could be attached to the standard M16A1 rifle. The weapon added 3 pounds to the weight of the rifle. The M79 launcher, nicknamed the "blooper," continued to be used by forces in Vietnam, including the US Marine Corps. Both weapons fired the same 40x46mm grenades. The design of the M203, however, precluded it from using cartridges over a certain overall length, a major issue that eventually led the replacement of that launcher. As a result, the M79 remained in inventory and limited usage for some period after the introduction of the M203.

In May 2004, US Marines with Headquarters Battalion, 1st Marine Division then deployed to Iraq, were reported to have tested M79 grenade launchers as a possible answer to neutralizing improvised explosive devices. The M79 was seen as potentially allowing the Marines the stand-off distance they needed to eliminate the threat and keep roads open for convoys. Having a single, dedicated weapon to handle IEDs would allow a "comfort" factor for which Marines were looking for when it comes defeating the explosive threat.