BLOOP! Spike’s Tactical Thumper M79, 37mm Flare Launcher

By Frank Iannamico

Along with the UH-1 Huey helicopter and M16 rifle, one of the icons of the Vietnam conflict would have to be the M79 grenade launcher. You may have read about them in books, seen them on TV in the news broadcasts of the day or perhaps had firsthand experience with one. If you are familiar with the M79, you might also recognize it from one of its nicknames—the blooper or thumper; so named for the sound it makes when launching its lethal payload.

During the late 1950s, research began on a new weapon design that would give the individual soldier a fire capability between the maximum range of a hand-thrown grenade and the minimum range of a mortar. Springfield Armory engineer Dave Katz under the direction of Cy Moore were involved in the development program. Ideally, the recoil was to be no more than that of a 12-gauge shotgun, with a muzzle velocity of 250 feet per second, providing a range of 400 meters, if launched with a quadrant elevation of 35 degrees. Implementing such a low-velocity round called for an unusual propellant system called the high-low type. Once ignited by the primer, the propellant’s expanding gases flow into a small high-pressure chamber. The pressure then bleeds through small holes into a larger low-pressure chamber immediately behind the projectile. Pressure in the low-pressure chamber is approximately 3,000 psi compared to 30,000 psi in the high-pressure chamber.

Visually, the M79 resembles a break-action shotgun with a very large bore, which earned it yet another epithet “the elephant gun.” A simple and basic design, there are only five major part groups; a receiver, forend assembly, a barrel group, a sight assembly, a wooden or plastic buttstock and foregrip. The barrel length of the launcher was 14 inches, long enough to make it unlikely that the shooter could accidentally place his fingers in front of the muzzle. A rubber pad was added to the stock to reduce the effects of recoil. The rear sight used on the M79 is a folding ladder-style leaf. When folded, the...

This article first appeared in Small Arms Review V22N10 (December 2018)
and was posted online on October 26, 2018


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