Home > Firearms > M203


40-mm underbarrel grenade launcher

M203 grenade launcher

The M203 was the first underbarrel grenade launcher, and is still the primary grenade launcher of the US armed forces, almost 50 years after its introduction

Country of origin United States
Entered service 1969
Caliber 40 mm
Cartridge 40x46 mm
Weight (empty) 1.36 kg
Length 380 mm
Barrel length 305 mm
Muzzle velocity 76 m/s
Cyclic rate of fire 7 rpm
Practical rate of fire 5 rpm
Magazine capacity 1 rounds
Sighting range 250 m
Range of effective fire (grenades) 150 m
Maximum range (grenades) 400 m
Range of effective fire (buckshot) 30 m


   The AAI M203 is the primary grenade launcher of the US armed forces, and was the first weapon of this type to achieve operational service. It has been long-lived in operational service, and both used and produced in many nations.

   The background of the M203 is inter-tangled with those of many other projects and weapon systems. It was developed in response to the GLAD (Grenade Launcher Attachment Development) program, which was intended to provide the US Army with an underbarrel grenade launcher for use on the Colt XM16E1 assault rifle (which soon entered service as the M16); a much more difficult task than it sounds today, as at the time, no such weapon had ever been developed in the US. The GLAD program and the M16 were both offshoots of Project SALVO, which had originally been planned in 1951 to produce a multi-barrel assault rifle that fired flechette projectiles at tremendous rates of fire. GLAD was preceded by another SALVO offshoot, Project Niblick, which produced the 40x46mm low-velocity grenade later needed for the GLAD weapon. Niblick also ultimately resulted in the development of the M79 grenade launcher that preceded the M203.

   Project Niblick didn't end with the M79, and it was from this program that the GLAD requirement arose from --- though despite being considered a distinct program, it was tied directly to Project SALVO, as there were three competing rifle designs, and three competing grenade launchers. After being formalized in 1964, three competing weapons were submitted by the industry to the GLAD program; one by Colt, one by H&R, and one by AAI. The Colt CLG-4 was declared the winner and type-classified as the XM148 (not to be confused with the earlier Springfield Armory T148, which was a precursor to the M79), and Colt was contracted in July of 1966 to produce 20 000 of them for field trials in Southeast Asia. The first XM148s arrived in South Vietnam that December.

   However, the US Army quickly regretted that decision. The Colt XM148 proved to be a disaster in actual combat conditions. It was prone to accidental discharges, was extremely laborious to field strip and clean, had numerous tiny parts that were easily lost in the field, and too heavy a trigger pull. This weapon was quickly pulled from service, and the Army soon reversed their decision in the GLAD program, awarding AAI a contract to build their grenade launcher after all. It was type-classified in November of 1968 as the XM203, and a month later the Army awarded AAI a contract to produce 600 of them for testing in Southeast Asia (apparently, the Army's enthusiasm for exceptionally large initial orders was blunted by the failure of the XM148). Though later testing would reveal problems in arctic conditions, the XM203 performed well in Vietnam, and it was formally adopted into operational service with the US armed forces in 1969.

   In appearance, the M203 more closely resembles *part* of a weapon than a complete weapon (which is not far from the truth, as it must be mounted on another weapon to use it). It consists of a long, partially-ribbed tube attached to a support rail above, and a trigger group aft. The aft ribbed portion of the barrel slides over the front of the barrel when the weapon is reloaded, and the chamber is located in this forward section. The upper rail not only supports the barrel, but is also used to attach the M203 to another weapon.

   It is impossible to operate the M203 successfully unless it is attached to a larger weapon, usually an assault rifle. There are exceptions to this rule though; for example, variants of the MP5 submachine gun. In US military service, the M203 is attached to an M16 or M4. Attaching the M203 to a weapon is a procedure requiring only 5 minutes, and the only tool required is a screwdriver.

   There are no sights on the M203; these must be fitted to the weapon that the launcher is attached to. Otherwise, the only reference with which to aim the launcher is the user's best guess. The sights fitted to the main weapon consist of a front leaf and a rear ladder, with settings from 50 m to 250 m in 50 m increments.

   To fire the M203, the operator must first unlock the barrel assembly via the barrel latch on the top-left side of the weapon, and slide the barrel assembly forward, and then backward, which cocks the weapon. The rear barrel assembly is then slid forward again, exposing the chamber; if an unfired round or a spent casing are in the chamber, it will be automatically extracted and ejected. A round may now be loaded into the chamber, and the slide drawn back. If completed properly, the extractor will catch the rim of the casing. The barrel is then locked into its fully-closed position by re-engaging the barrel latch, and the M203 may now be fired by simply pulling the trigger.

   The M203 may be fired from the shoulder in standing, kneeling, or prone positions. There is no backblast hazard, and a minimal muzzle blast hazard, allowing the weapon to be safely fired from any confined space. The weapon bearing the M203 may also be braced with its buttstock against the ground and the muzzle aimed upward, allowing the M203 to be used like a mortar. This is best accomplished from a sitting or prone position. It is also possible to fire the M203 from the hip, but accuracy will suffer accordingly. As it is mounted under the front of a larger weapon, the M203 cannot be fired one-handed like a pistol, as with the M79.

   A number of operational hazards in operating the M203 have also been identified, including reliability problems in severe cold conditions (though the M203's cold weather problems have since been remedied), and the omission of a safety mechanism. A now famous quote from a US Army preventative maintenance magazine also states, "A slipping gear could let your M203 grenade launcher fire when you least expect it. That would make you quite unpopular in what's left of your unit.".

   The grenades fired by the M203 are the same as used in the M79; see the page on that weapon for a brief description of some of them.

   The M203 first saw combat during the Vietnam War, in which it was deemed a great success. It has since been used by many nations in seemingly innumerable conflicts all over the world, also usually successfully.

   In addition to AAI Corporation, numerous other US companies have produced M203s under license, including Knight's Armament, Bushmaster, Airtronic USA, R/M Equipment, US Ordnance, the Lewis Tools & Machinery Company, and --- ironically --- Colt Defense. AAI themselves only produced 10 000 M203s, before passing-on production to these other companies. It has also been manufactured abroad by Colt Canada and Diemaco in Canada, Daewoo in South Korea, the Floro International Corporation in the Philippines, and Maadi in Egypt. MKEK in Turkey manufactures the T-40, a variant of the M203.

   The M203's operators include Afghanistan, Albania, Australia; Austria; Bangladesh, Brazil, Brunei, Cambodia, Cameroon, Canada, Chile, Columbia, the Czech Republic, Denmark, the Dominican Republic, Ecuador, Egypt, El Salvador, France, Gabon, Greece, Honduras, India, Indonesia, Iraq, Ireland, Israel, Italy, Japan, Jordan, Kuwait, Lebanon, Liberia, Malaysia, Mexico, Morocco, Myanmar, the Netherlands, New Zealand, Oman, Pakistan, Panama, the Philippines, Portugal, Qatar, Saudi Arabia, Singapore, South Korea, Sri Lanka, Sweden, Thailand, Turkey, the UAE, the UK, the US, and Vietnam.

   The M203 is still produced by its various manufacturers, even now after nearly 50 years of continuous mass production. New example costs between $1 000 and $2 000.

   In US service, the M203 is slated to be replaced in the 2020s by the M320, another 40-mm underbarrel grenade launcher.




   M203: Original production model. It can be mounted on the M16A1, M16A2, or M16A1, but not on an M4 or an M16A4.

   M203A1: Shorter M203 for use on carbines, such as the Colt M4. It has a shorter 229 mm barrel.

   M203A2: Improved M203 for use on the M16A4. Using the M5 MWS Rail System, it can also be attached to an M16A2.

   M203 DAX: Improved M203 with a double action trigger, and a resized chamber that will accommodate a variety of less-lethal rounds.

   M203PI: A modified M203A1 for use on a wide variety of other rifles. For example, the Irish Army employs the M203PI on the Steyr AUG, which is too short for a standard M203, and won't accept the M203A1.

   K201: M203 built under license in South Korea by Daewoo.

   FIC M203: M203 built under license in the Philippines by the Floro International Corporation.

   T-40: Turkish grenade launcher based on the M203, manufactured by MKEK.

   SPG-1: M203 built under license in Indonesia by PT Pindad.

   Gk M/98: Danish designation for the M203.

   Type 91: Chinese 35-mm underbarrel grenade launcher for use on a variety of rifles. It is similar in concept to the US M203. There are also standalone versions of the Type 91.



   Article by BLACKTAIL

   Want to publish your own articles? Visit our guidelines for more information.

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

M203 grenade launcher

Home  Home     Aircraft     Helicopters     Tanks     Armored Vehicles     Artillery     Trucks     Engineering Vehicles     Missiles     Naval Forces     Firearms     |     Contact Us

ARG 2006 - 2017
www.Military-Today.com M203