M203 Grenade Launcher

Origins

The American 40 mm grenade was introduced in the early 1960s with the M79 Grenade Launcher, a single-shot break-open weapon that fired a small explosive shell to about 350 meters. It was a great success in the Vietnam War, but the grenadier who carried it had only a pistol for close defense, and in the jungle that was a real weakness. The Army first tried the XM148, a launcher by Colt that fitted under the barrel of the M16 Rifle. It was sent to Vietnam in 1967 for trials, but its awkward cocking lever and exposed trigger drew complaints. The AAI Corporation of Maryland then designed a simpler replacement, the XM203. Field trials in Vietnam in 1969 went well, and it was adopted as the M203, with Colt taking over large-scale production in the early 1970s.

Design & Construction

The M203 is a light aluminum tube with a rifled barrel about 305 mm (12 inches) long, attached under the M16's handguard in place of the lower handguard. It weighs about 1.4 kg unloaded. To load, the firer presses a latch and slides the barrel forward, drops a round into the breech and slides it back to close it. The launcher has its own trigger and safety in front of the rifle's magazine, so the soldier can switch between rifle and grenade fire without changing grip. A folding leaf sight on the handguard and a quadrant sight on the carrying handle are used to aim. The weapon fires the 40x46 mm low-velocity family of rounds. The most common are the M406 high-explosive shell and the M433 high-explosive dual-purpose round, which also has a shaped charge able to pierce light armor. Buckshot, colored smoke, flares, tear gas and practice rounds are also used. Point targets can be engaged to about 150 meters and area targets to about 350 meters. The M203A1, with a 9-inch barrel, was made for the M4 Carbine, and the M203A2 added improved sights.

Combat Use

The M203 arrived too late to see much service in Vietnam beyond its trials, and the M79 remained in use there to the end. Through the Cold War / Modern Era it became part of the standard American infantry squad, with one or two grenadiers in each fire team. It was used in Grenada in 1983, Panama in 1989 and the Gulf War of 1991, and by Army Rangers, special forces and Marines in Somalia in 1993. In Afghanistan and Iraq after 2001 it was mounted on M16A2 and M16A4 rifles and M4 carbines, and grenadiers used it to reach enemy fighters behind walls, in ditches and on rooftops that rifle fire could not reach. Many other armies adopted it or copies of it, and some fitted it to rifles other than the M16.

Legacy

From 2009 the US Army began to replace the M203 with the Heckler & Koch M320, which opens to the side, can take longer rounds, and can be fired as a stand-alone weapon with its own stock. The Marine Corps followed with the M320A1. Many M203s remain in service around the world. Its basic idea, a single-shot launcher slung under a rifle, has been copied widely, from the Soviet GP-25 to European designs, and has become a standard feature of modern infantry forces.