The M79 was a result of the
US Army's
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 40 x 46 mm 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 three-shot "harmonica"
T148 (not to be confused with the later, underbarrel
XM148), which did see some limited production and fielding in Vietnam, but problems with the three-round magazine prevented widespread acceptance. The other design was a single-shot break-open, shoulder-fired weapon, the S-3. This was refined into the S-5, which resembled an oversized single-barrel shotgun. Unable to solve the problems with the multi-shot T148 launcher, the Army adopted the S-5 as the XM79. With a new sight, the XM79 was officially adopted as the M79 on December 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. The M79 saw combat in the Vietnam War beginning in the early days, when M79 grenadiers assigned to major Army divisions first arrived to see combat in Vietnam in 1965, including the 1st Cavalry Division, the 1st Infantry Division, the 101st Airborne Division, and the 173rd Airborne Brigade. M79s were assigned to the specialist 4 grenadier in both 4-5-man fire teams organic to an Army rifle squad headed by a squad leader. The Marines assigned one grenadier to their three-fireteam 14-man rifle squad. However, its single-shot nature was a serious drawback. Reloading after every shot meant a slow rate of fire and an inability to keep up a constant volume of fire during a firefight. This led the Navy to develop the
China Lake Grenade Launcher, which was produced for deployed SEAL Teams. For close-in situations, the minimum arming range (the round travels 30 meters to arm itself) and the blast radius meant a grenadier had to use his .45 ACP (11.43 mm)
M1911 pistol, or fire and hope that the grenade acted as a giant slow bullet. Special grenades for close-in fighting were created to compensate, though a soldier was not always able to load one in the heat of battle. Moreover, the size and weight of both the M79 and its ammunition meant that a
grenadier armed with this weapon could not also carry a rifle, having only a sidearm to use in a firefight after expending his rounds. Some grenadiers did choose to carry a slung
M16 rifle in lieu of a sidearm. Underbarrel grenade launchers, such as the
XM148 and the
M203, both designed as attachments for the M16 rifle, were developed during the Vietnam War, allowing the grenadier to also function 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 although M79s were still used in
Reserve and
National Guard units. Some
US Navy SEALs and
Army Special Forces in
Iraq were seen using the M79 due to its greater accuracy and range compared to the M203 (350 meters effective versus 150 meters effective). The M79 saw notable limited use during
Operation Iraqi Freedom, such as for clearing
IEDs. The grenade launcher also sees continued use as a mission-specific tool with
Special warfare combatant-craft crewmen. ==Design==