#m320

M203 Grenade Launcher

In May 1963, the US military called for a new ‘underslung’ grenade launcher to complement the AR-15, then in early testing. The grenade launcher program had its roots in the ultimately unsuccessful Special Purpose Individual Weapon (SPIW) program which had begun in 1951.

While various manufacturers and designers developed a series of designs, May 1964 saw Colt unveil the CGL-4. Designs from Colt, Springfield Armory and Ford were all tested. Another design from AAI was promising but it was not able to chamber the 40x46mm rounds used by the M79 and the Ordnance Corps rejected it.  The US military sought munitions commonality between the M79, already in service, and the new rifle-mounted grenade launcher.

A Colt CGL-4/XM148 in Vietnam (source)

Colt’s CGL-4 was extensively tested between 1965 and 1967 under the designation XM148. Colt manufactured 27,400 XM148s with many of these deployed to Vietnam for field testing. Despite Colt’s efforts to rectify the growing list of problems the Army Concept Team In Vietnam deemed the XM148 unsatisfactory for deployment in Vietnam. The Army Concept team recommended the removal of the Colt from service and development of a new improved launcher begin.

While the XM148 proved to be a failure it played an important role in proving the operational viability of the rifle mounted grenade launcher system. The muzzle-launched rifle grenade is all but obsolete, superseded by the underslung grenade launcher.

The US Army launched the Grenade Launcher Attachment Development (GLAD) program in the summer of 1967. A large number of manufacturers submitted designs including Colt, who offered the improved Henry Into-designed CGL-5. The Army turned down Colt’s offer of 20 free improved launchers and rejected the CGL-5 outright. The GLAD program saw the resurgence of the earlier AAI design, designated the XM203, this simple design, now chambering the 40x46mm shell, was eventually selected in August 1968. 

The M203′s Quadrant sight assembly (source)

Testing began in May 1968, with Philco-Ford and Aero Jet also submitting designs. The AAI XM203 quickly proved to be the leading design and was unanimously selected based on its superior performance and cost efficiency. In November the Army placed an order for 500 trials XM203s, and a stock to allow use of the launcher without a rifle was also in development. While AAI eventually abandoned the stock project the US Army moved to formally adopt the XM203 in 1969.  

The first AAI launchers reached US units in Vietnam in April 1969 and was well received by troops as it was more robust and less prone to snagging on kit and brush than the Colt XM148. Following a three month combat evaluation program the US Army adopted the AAI launcher as the M203. The M203 weighs 1.36 kg (3.0 lbs) and is 38cm (15in) in length. The M203 is a single-shot, ‘pump action’ launcher, the operator unlocks the breech and pushes the barrel forward to open the action. It chambers a variety of 40mm ordnance ranging from high explosive and buckshot to illumination rounds and smoke grenades. The M203 is much simpler than the XM148. It’s front ladder sight can be used in conjunction with an M16′s iron sights or the operator can attach a more complex quadrant sight.

Ironically, as AAI was predominantly a research and development company and after an initial run of 10,000 made by AAI, Colt was subsequently awarded the contract to manufacture the M203 from 1971 onwards. Various companies have since made over half a million M203s. A number of nations have fitted the launcher has to a wide variety of rifles including the Steyr AUG and the Daewoo K2. The US currently plan to phase out the M203, replacing it with the M320, developed by Heckler & Koch.    

Sources:

Images: 1 2 3 4 

Black Rifle, E.C. Ezell & R. Blake Stevens, (1987)

40mm Shoulder-Fired Grenade Launchers & the SEALS, Small Arms Review, K. Dockery, (source)

Field Manual, 40-MM Grenade Launcher, M203 (source)

@indyart these look a little more wieldy than the m203. It’s wild to me that these can be mounted on a RIS, basically mounted via pressure on the delta ring.