The M-79, One Weapon, Many Silly Names and Tremendous Firepower

M79 garnered popularity among soldiers during the Vietnam era for its user-friendliness, high reliability, and minimal maintenance requirements.

The M79 grenade launcher is a single-shot, shoulder-fired, break-action weapon designed to fire a 40×46mm grenade. It utilizes the High-Low Propulsion System, a feature developed by the US Army to minimize recoil forces. Originating during the Vietnam War, its distinctive sound has led to a variety of colorful nicknames among American soldiers, including "Thumper," "Thump-Gun," "Bloop Tube," "Big Ed," "Elephant Gun," and "Blooper." Australian units humorously referred to it as the "Wombat Gun." The M79 is capable of launching a diverse array of 40 mm rounds, encompassing explosive, anti-personnel, smoke, buckshot, flechette, and illumination options. Although largely replaced by the M203, the M79 continues to serve in specialized roles within various military units worldwide.

The M79 originated from the US Army's Project Niblick, which aimed to enhance infantry firepower by introducing a more accurate explosive projectile with greater range than rifle grenades, yet more portable than a mortar. Project Niblick led to the development of the 40 x 46 mm grenade, but encountered challenges in creating a satisfactory launcher capable of firing multiple shots. One of the prototypes, the three-shot "harmonica" T148, underwent limited production and deployment in Vietnam but faced issues with its magazine, hampering widespread acceptance. Another design was the single-shot break-open, shoulder-fired weapon known as the S-3, later refined into the S-5, resembling an oversized single-barrel shotgun. Failing to resolve the challenges with the multi-shot T148 launcher, the Army adopted the S-5 as the XM79. Equipped with a new sight, the XM79 was officially designated as the M79 on December 15, 1960.

The M79 grenade launcher made its debut in combat during the Vietnam War in the early 1960s. M79 Grenadiers were initially deployed with major Army divisions such as the 1st Cavalry Division, the 1st Infantry Division, the 101st Airborne Division, and the 173rd Airborne Brigade. Within Army rifle squads led by a squad leader, M79s were assigned to specialist 4 grenadiers, forming 4-5-man fire teams. Similarly, the Marines incorporated one grenadier into their 14-man rifle squad, organized into three fireteams. This deployment structure ensured that the M79 played a crucial role in providing explosive support to infantry units operating in the challenging terrain of Vietnam.

The M79 grenade launcher's single-shot design posed a significant limitation in combat. Its need for reloading after each shot resulted in a slow rate of fire and an inability to sustain continuous fire during engagements. Recognizing this drawback, the Navy initiated the development of the China Lake Grenade Launcher, specifically for deployed SEAL Teams.

To address the shortcomings of the M79, underbarrel grenade launchers like the M203 were developed during the Vietnam War. Designed as attachments for the M16 rifle, these launchers allowed grenadiers to switch between grenade launcher and rifle roles seamlessly and the M203 proved successful and was standardized in 1969. By the end of the war, the M203 had largely replaced the M79, although the latter continued to see use in Reserve and National Guard units.