The M79 Grenade Launcher
The M79 would earn many nicknames. The "bloop-tube" and "thumper" were common because of the sound the weapon would make when fired. The M79 would be useful in forcing the enemy from dug in positions and to suppress heavily fortified positions. It shot multiple kinds of rounds, for example explosive rounds, shotgun rounds, and smoke rounds.
The M79 was carried in order to replace rifle grenades, and effectively did so. The dedicated grenade launcher saw a lot of action over the course of the war, with its users becoming extremely skilled and being very valuable members of the platoon who could disrupt enemy forces and break up large numbers.
Arques, Antonio. "M79 Grenade Launcher." Grunt: A Pictorial Report on the US Infantry's Gear and Life during the Vietnam War 1965-1975, by Arques, Madrid, Andrea Press,
2014, pp. 352-53.