Its distinctive report has earned it colorful nicknames, such as "Thumper", "Thump-Gun", "Bloop Tube", "Big Ed", "Elephant Gun", and "Blooper" among American soldiers[5] as well as "Can Cannon" in reference to the grenade size; Australian units referred to it as the "Wombat Gun".

[6] The M79 can fire a wide variety of 40 mm rounds, including explosive, anti-personnel, smoke, buckshot, flechette (pointed steel projectiles with a vaned tail for stable flight), and illumination.

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.

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.

Owing to its ease of use, reliability, and firepower, the M79 became popular among American soldiers, who dubbed it "the platoon leader's artillery".

This led the Navy to develop the China Lake Grenade Launcher, which was produced for deployed SEAL Teams.

Moreover, the size/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.

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.

Additionally, Appendix A of the U.S. Army field manual for the M203 includes instructions on attaching the M16 rifle grenade sight to the M79's stock and marking the sling for indirect fire at elevations greater than 40°.

While not manufacturers of the M79, Milcor and Denel Mechem of South Africa do re-manufacture M-79 grenade launchers to more modern standards.

The hammer is cocked when the breech is opened, and a spent casing may then be removed (if present) and a new round loaded.

Outside of the smoke and illumination rounds three main types emerge: explosive, close-range, and non-lethal crowd control.

[16] The round would not arm at point blank ranges and it usually did not have enough kinetic energy to kill, although it sometimes penetrated the abdomen or caused large hematomas.