January 29, 2008: Convoy operations in Iraq and Afghanistan have revealed some weapons to be more suitable for that kind of combat, than others. In particular, the troops like the Mk19 automatic grenade launcher. This weapon can fire 40mm grenades, out to about 2,000 meters, at a rate of 5-6 per second. When you have a bunch of people shooting at you, and you are not sure exactly where they are, the Mk19 is an excellent weapon for covering lots of ground with exploding grenades. Each 40mm, one pound, grenade can kill people within five meters of the explosion, and wound out to fifteen meters. For an ambush, wounding the attackers is sufficient to weaken, and eventually shut down, the gunfire coming at you. The only problem is that this kind of fire requires an experienced operator, and careful maintenance of the relatively complex and temperamental Mk19.

Automatic grenade launchers, firing low speed 30-40mm shells, became popular in the 1960s when the usefulness of the American single shot M79 40mm grenade launcher was noted. Many troops today want the M79 back. But back then, Russia and the United States proceeded to develop automatic grenade launchers. This was actually the second generation, as the Russians originally developed such weapons in the 1930s. By 1939 the Russian Navy was testing a 40.8mm weapon, and the army followed a year later. The 21 ounce shells were based on the Djakonow rifle grenade and were fired at 400 feet per second (about 40 percent the speed of a pistol bullet) for a maximum range of 1200 meters. The weapon weighed 53 pounds and was used in the 1940 Winter War with Finland. For political reasons (the weapons designer fell out of favor), the weapon was withdrawn from service before the Germans invaded in 1941 and was forgotten. This sort of thing happens a lot.

In 1965, the U.S. developed and put into service the M18 40mm automatic grenade launcher. This weapon used the same 40mm round as the M79. The 19 pound M18 used a hand crank to load rounds (from a belt). Work on this weapon actually began in 1962, but it took the popularity of the M79 in Vietnam to spur production. Some 1200 M18s were built through 1968, and it was a popular weapon on U.S. Navy river patrol boats, where ambushes were frequently encountered. Starting in 1966, the M18 was replaced by the heavier M19 that was truly automatic, but weighed 75 pounds. This was also developed by the U.S. Navy. Russia followed in 1974 with the AGS17, a 30mm grenade launcher weighing the same as the M19, but firing a ten ounce shell instead of the 16 ounce 40mm shell used in American weapons.

Dozens of countries now build weapons using the 40mm (and 30-35mm as well) shells. Unlike the original 1930s weapon, the modern ones operate at lower velocities (usually 250-300 feet per second). Despite the clumsiness of the M203 40mm grenade launcher (fitted beneath the M-16s barrel), the 40mm grenade remains useful, and popular, in combat. Many countries still make stand alone launchers, often with a six round revolver design. These weigh under fifteen pounds, but do not allow the user to immediately switch to rifle fire, as with the M203. These 40mm "six guns" are also considered clumsy to carry and use. Looks great in movies, but the combat troops would rather have an M79, also known as the "thump gun," for the characteristic sound it made when fired.

American troops want the M79 back because it is more accurate than the M203. They also note that the U.S. Army Special Forces still uses M79s, which have been scrounged from stockpiles of retired, but not yet destroyed, weapons. The M79 is pretty simple, since it's basically a six pound, single shot, shotgun that fires 40mm grenades instead of shot. In the hands of an experienced operator, the M79 can put those 40mm grenades on any target within 300 meters. Very handy, since it can reach enemy troops behind cover or inside rooms (if an open window is available. )