M79 with the leaf-type sight unfolded.
The M79 grenade launcher is a single-shot, shoulder-fired, break-action grenade launcher that fires a 40x46mm grenade which uses what the US Army calls the High-Low Propulsion System to keep recoil forces low, and first appeared during the Vietnam War. Because of its distinctive report, it has earned the nicknames of "Thumper", "Thump-Gun", "Bloop Tube", and "Blooper" among American soldiers. Australian units referred to it as the "Wombat Gun". The M79 can fire a wide variety of 40mm rounds, including explosive, anti-personnel, smoke, buckshot, flechette, and illumination. While largely replaced by the M203, the M79 has remained in service in many units worldwide in niche roles.
History[]
The M79 was a result of Project Niblick, an attempt to increase firepower for the infantryman by having an explosive projectile more accurate with further range than rifle grenades, but more portable than a mortar. Project Niblick created the 40x46mm grenade, but was unable to create a satisfactory launcher for it that could fire more than a single shot. One of the launchers at Springfield Armory was the single-shot break-open, shoulder-fired S-3. It was refined into the S-5, which resembled an over-sized shotgun. Unable to develop a suitable multi-shot launcher, the Army adopted the S-5 as the XM79. With a new sight, the XM79 was officially adopted as the M79 on Dec. 15, 1960.
In 1961, the first M79 grenade launchers were delivered to the US Army. Owing to its ease of use, reliability, and firepower, the M79 became popular among American soldiers, who dubbed it "the platoon leader's artillery". Some soldiers would cut down the stock and barrel to make the M79 even more portable.
However, its single-shot nature was a serious drawback; having to reload after evry shot meant a slow rate of fire and therefore an inability to keep up a constant volume of fire during a firefight. Also, for close-in situations, the minimun arming range (the round must travel 30 meters to arm itself) and the blast radius meant a grenadier would have to either resort to a backup pistol, if he had one to begin with, or fire and hope that the grenade would not arm itself but instead act as a giant slow bullet. Specialty grenades for close-in fighting were created to compensate, though a soldier did not always have the luxury to being able to load one in the heat of battle. Moreover, its size meant that a soldier with an M79 would be dedicated to being only a grenadier, and if he ran out of ammunition had nothing but a pistol and knife to contribute to a firefight. Underbarrel grenade lauchers, such as the XM148 and the M203, where the grenade launcher attaches to the rifle, were developed during the Vietnam War, allowing the grenadier to function also as a rifleman.
The XM148 was plagued with problems and the project was dropped. The M203 was a success, and was standardized in 1969; it had replaced the M79 by the end of the war, though M79s were still used in Reserve and National Guard units. Some US Navy SEALs and Army Special Forces in Iraq have been seen using the M79 in recent years, most likely due to its greater accuracy and range compared to the M203 (350m effective range versus 150m effective on the M203). The M79 has seen notable limited use during Operation Iraqi Freedom, such as for clearing IEDs.
Design[]
Visually, the M79 grenade launcher resembles a large bore, break-action, sawed-off shotgun, and is simple in design, having only five parts: a receiver group, a fore-end assembly, a barrel group, a sight assembly, and a stock. The fore-end assembly beds the barrel to the receiver. The stock is made out of wood or fiberglass. A rubber pad affixed to the buttstock absorbs some recoil. The front sight is a fixed blade. The rear sight on the M79 is a folding ladder-style leaf-type sight. When folded, the leaf sight acts as a fixed for close range. A grenadier may simply point and shoot for high accuracy. When unfolded, the leaf type sight could be adjusted for ranges from 75 meters to 375 meters, in 25 meter increments. Additionally, Appendix A of US Army field manual for the M203 includes instructions for attaching the M16 rifle grenade sight to the M79's stock and marking the sling for indirect fire at elevations greater than 40 degrees.
Operation[]
The M79 is easy to operate. To load, the grenadier pushes the barrel locking latch on the receiver to the right. Gravity will pull down the barrel, breaking it open and exposing the breech. The hammer is cocked when the breech is opened. A round may then be loaded. The break action must then be closed manually. Closing the breech will cause the barrel locking latch to return to center. The safety must then be pushed to the forward position in order to ready the weapon for firing.
Ammunition[]
Many different ammunition types were produced for the M79, outside of the smoke and illumination rounds three main types emerge: explosive, close-range, and crowd-control. The break-open action of the M79 allows it to use longer rounds than the standard M203 cannot use without some difficulty.
Explosive[]
The M406 40mm HE (High Explosive) grenades fired from the M79 travel at a muzzle velocity of 75 meters per second. The M406 contained enough explosive to produce over 300 fragments that travel at 1,524 meters per second within a lethal radius of 5 meters. This round incorporated a spin-activation safety feature which prevents the grenade from arming while still within the range of the shooter; it armed itself after traveling a distance of about 30 meters. Even though the round would not arm at point blank ranges, the round still had enough kinetic energy to kill or seriously injure its target.
Close range[]
For close range fighting, two styles of M79 rounds were developed. The first was a flechette or Bee Hive round that fired 45 10-grain steel flechettes. Flechettes proved to be ineffective because they would often not hit point-first and penetrate. Instead, they would hit sideways and bounce off. About 1966, this was replaced by the M576 buckshot round. Containing 20 24-grain metal pellets (M576E1) or 27 24-grain pellets (M576E2), this round could be devastating at close ranges. However, as range increased, the shot spread out so rapidly as to be ineffective. The M576E2, despite the greater number of shot, was less effective at range than the M576E1, because its shot spread out much more quickly and could completely miss the target.
Non-lethal[]
The M79 has been used extensively also for crowd control purposes where it is desireable to have a weapon dedicated solely to non-lethal force. The three common less-lethal roounds are the M651 CS gas, the M1006 sponge grenade, and the M1029 Crowd Dispersal rounds.
