M203 40mm Grenade Launcher Attachment Development (GLAD)
The M203 40mm Grenade Launcher was designed and procured as the replacement for the M79 grenade launcher of the Vietnam era. In August 1969 the Army accepted the M203 40-mm. grenade launcher attachment for the M16A1 rifle. The M203 replaced the M79, uses the same ammunition, and provides the grenadier with a weapon that is both a rifle and a grenade launcher. The M79 served only as a launcher and deprived the rifle squad of two rifles. When Picatinny teamed the M203 Grenade Launcher with the M16A2 rifle, it gave a single infantryman more firepower than an entire infantry platoon with artillery support had in the Civil War.
The M203 is used while attached to an M16A2 5.56mm rifle. It is a lightweight, compact, breech loading, pump action, single shot launcher. The launcher consists of a hand guard and sight assembly with an adjustable metallic folding, short-range blade sight assembly, and an aluminum receiver assembly which houses the barrel latch, barrel stop and firing mechanism. The launcher is capable of firing a variety of low velocity 40mm ammunition. The launcher also has a quadrant sight which may be attached to the M16A2 carrying handle and is used when precision is required out to the maximum effective range of the weapon. The M203A1 has a short barrel for airborne applications and a quick release mechanism to allow the user to tailor the weapon to individual missions.
The M203 can engage a window sized target out to 150 meters and an area type target out to 450 meters. The soldier is trained to apply the marksmanship principles: steady position, aiming, breath control, and trigger squeeze. The soldier will fire training practice rounds and one high explosive round for familiarization. The soldier will be trained to correctly zero the sights, correct a malfunction, and perform maintenance on the M203.
The leaf sight is a folding, adjustable open ladder design that permits rapid firing with out manipulation. The leaf sight uses the front sight post of the M16A2 rifle as the front aiming post. The leaf sight base is permanently attached to the rifle hand guard by two mounting screws. The leaf sight base serves to protect the leaf sight from damage when the leaf is not being used and is in the down position. The leaf sight mount is attached to the sight base and is used to rise and lower the sight leaf blade. The leaf sight is graduated in 50-meter increments from 50 to 250 meters.
The quadrant sight assembly mounts on the left side of the carrying handle of the M16A2 rifle. The quadrant sight arm serves a dual purpose. It mounts the sight aperture arm (which holds the sight aperture) and the sight post arm (which holds the front sight post). Use the following procedure to fire with the quadrant sight. The front sight post can be used to make minor adjustments in elevation when zeroing the launcher. For elevation adjustments, turn the adjustment screw on the sight post clockwise to decrease elevation and counterclockwise to increase elevation. One full turn on the adjustment screw will move the impact of the projectile 5 meters at a range of 200 meters. The rear sight aperture can be adjusted for minor changes in deflection when zeroing the launcher. For windage adjustment, press the rear sight retainer and move the aperture away from the barrel to move the impact to the left. One notch on the rear aperture will move the impact of the projectile 1-½ meters at a range of 200 meters.
The high explosive grenade has an effective casualty radius of 5 meters. The effective casualty radius is defined as the radius of a circle about the point of detonation in which it may be expected that 50 percent of exposed troops will become casualties. Safe-weapon practices for firing the M203 grenade launcher require a minimum safe distance of 130 meters for high explosive rounds, and 165 meters for HEDP. Range regulations stipulate that all targets have to be more than 200 meters away. The danger radius of the HE Grenades is 130 meters (427 ft). The M386, M397, M397A1, M406, and M433 rounds arm within 14 to 27 meters (46 to 89 ft). The M361 and M441 rounds arm within 2.4 to 3 meters (8 to 10 ft).
The Marine fire team leader/grenadier employs the grenade launcher in the offense to destroy groups of enemy personnel and to provide close fire support in the assault in conjunction with, and to supplement, other supporting fires. The fire team leader/grenadier personally selects targets and delivers the fire of the grenade launcher during the attack. In the last 35 meters of the assault, when the fires of the grenade launcher may endanger friendly assaulting troops on the objective, the fire team leader/grenadier employs the multiprojectile antipersonnel round. The multiprojectile round can be fired from the assault skirmish line without endangering the other assaulting Marines. The fire team leader/grenadier can fire high explosive rounds at targets which are far enough away so that the exploding HE round will not endanger the assaulting squad. HE rounds require an arming distance of approximately 30 meters.
During the assault, the fire team leader/grenadier may employ his rifle until suitable targets appear or until he has time to reload the M-203. Suitable M-203 targets are enemy automatic rifle positions, machine gun positions, and other crew served weapons within the fire team sector. This method of employment is used when a heavy volume of fire is needed.
In the defense the fire team leader/grenadier’s firing position should enable him to control his fire team and deliver grenade launcher fires over the entire fire team sector of fire. Primary and supplementary positions are prepared which provide maximum cover and concealment consistent with the assigned mission. Extreme care must be taken to ensure that fields of fire are cleared of obstructions which might cause premature detonation of the projectile. As the enemy approaches the defensive position, he is subjected to an ever increasing volume of fire. Initially, the fire team leader/grenadier should use the rifle portion of the weapon. As the enemy gets nearer to friendly positions, he should use the grenade launcher. He will fire on enemy automatic weapons and enemy troops who are in defilade. This will silence an enemy base of fire and cause enemy troops to leave covered positions so the automatic riflemen can engage them.
One final critical factor in selection of non-lethal systems was the need to be able to deliver the munitions using the organic weapon systems in the Marine rifle company's table of equipment. Learning new delivery systems would require additional training time and increase the combat load of the individual Marine. The decision was to require that new material could be fired from the M203, a combination of grenade launcher and rifle, and the standard 12-gauge shotgun. The M203 grenade launching system was compatible with the 37mm non-lethal munitions procured for Operation United Shield and was the preferred delivery system for these munitions. The M203 includes the M-16 and can provide lethality promptly when required. The infantry's familiarity with the M203 contributed to accuracy in non-lethal systems as well. The 12-gauge shotgun also provides versatility, and can easily be employed as a lethal weapon by quick selection of munitions.
Weight:
Launcher: 3 pounds (1.36 kilograms)
Rifle (M16A2): 8.79 pounds (3.99 kg)
Total (including 30 rounds): 11.79 pounds (5.35 kg)
Bore diameter: 40mm
Maximum effective range:
Area target: 1148.35 feet (350 meters)
Point target: 492.15 feet (150 meters)
Maximum range: 1312.4 feet (400 meters)
Minimum safe range:
Training: 426.53 feet (130 meters)
Combat: 101.71 feet (31 meters)
Unit Replacement Cost: $601
