US Mk 19 Grenade Launcher
1. Overview
The Mk 19 Grenade Launcher (pronounced “Mark 19”) is an American 40 mm belt-fed, blowback-operated, air-cooled, fully automatic grenade launcher. First developed during the Vietnam War as a weapon for riverine patrol craft, the Mk 19 has evolved into one of the US military’s primary crew-served support weapons, capable of delivering devastating suppressive and destructive fire against enemy personnel, lightly armored vehicles, and fortified positions. Designated as a “Grenade Machine Gun” (GMG), it remains in widespread service with the US Armed Forces and over 30 allied nations.
⚠️ SAFETY WARNING: All ordnance should be considered dangerous until proven safe by qualified personnel. This information is for educational and identification training purposes only.
2. Country/Bloc of Origin
- Country of Origin: United States of America
- Period of Development: 1963 (Mk 18 precursor); Mk 19 Mod 0 developed 1966; Mk 19 Mod 3 (current) redesigned 1976, adopted by US Army 1983
- Primary Manufacturer: Saco Defense Industries (now General Dynamics Ordnance and Tactical Systems — GDOTS); also produced by US Ordnance and Combined Service Forces
- International Production: In November 2014, General Dynamics entered an agreement with Advanced Material Engineering Pte Ltd (subsidiary of Singapore Technologies Kinetics) for international manufacture
- Users: Over 30 countries including the United States, Australia, Canada, Israel, South Korea, Egypt, and many NATO allies
3. Ordnance Class
- Type of Weapon: Belt-fed, fully automatic grenade launcher (Grenade Machine Gun)
- Primary Role: Infantry fire support; anti-personnel, anti-light armor, anti-fortification
- Delivery Method: Crew-served; tripod-mounted (M3 tripod) or vehicle-mounted on various platforms (HMMWV, M113, AAV, small attack boats, fast attack vehicles)
- Caliber: 40×53 mm high-velocity grenade
4. Ordnance Family / Nomenclature
- Official Designation: Mk 19 Mod 3 40mm Grenade Machine Gun
- NSN: 1010-01-126-9063 (Mk 19 Mod 3)
- Variants:
- Mk 18 — Predecessor; hand-cranked multiple grenade launcher (1963)
- Mk 19 Mod 0 — First automatic version (1966); crude, unreliable, and unsafe
- Mk 19 Mod 1 — Improved version (1972); approximately 1,000 produced; successfully deployed on riverine patrol boats in the Mekong Delta
- Mk 19 Mod 2 — Experimental lightweight version (1974); never progressed beyond prototype
- Mk 19 Mod 3 — Complete redesign (1976); type classified by US Navy 1981; adopted by US Army 1983; current production model
- Successor Systems: Mk 47 Mod 0 Striker (limited service with USSOCOM); XM307 ACSW (cancelled)
- Swedish Designation: Grsp 92
- Associated Components: MK64 Cradle Mount (Mod 5), M3 Tripod Mount, AN/TVS-5 Night Vision Sight
- Unit Replacement Cost: Approximately $13,758 (historical figure)
5. Hazards
- High-Explosive Fragmentation: The primary M430 HEDP round kills personnel within a 5-meter radius of impact and wounds within 15 meters. Mass employment creates extensive lethal fragmentation zones.
- Armor Penetration: HEDP rounds penetrate up to 2 inches (51 mm) of rolled homogeneous armor at 0-degree obliquity, meaning they can defeat most infantry fighting vehicles and APCs.
- Minimum Safe Distances:
- Training: 310 meters
- Combat: 75 meters
- These distances reflect the combined effects of blast and fragmentation from the 40 mm grenades
- Ammunition Hazard: The 40×53 mm ammunition is high-velocity and NOT interchangeable with 40×46 mm ammunition used in the M203/M320. The 40×53 mm develops significantly higher chamber pressure and velocity. Loading incorrect ammunition type would be catastrophic.
- Cook-Off Resistance: The Mk 19 fires from an open bolt and is designed not to cook off, with low barrel temperatures during rapid fire. However, standard precautions for automatic weapons apply.
- Weight/Handling: The complete system (gun, cradle, tripod) weighs approximately 137.5 lbs (62.4 kg), creating significant handling and mounting hazards.
- Backblast: Minimal compared to recoilless weapons, but operators should be aware of ejected cartridge cases and links to the right side.
- Indirect Fire Capability: The Mk 19 can deliver indirect fire from defilade positions, meaning rounds may arrive with little warning at the target area.
6. Key Identification Features
- Overall Appearance: Boxy, rectangular receiver with a distinctive long barrel and large feed mechanism on top
- Length: 43.1 inches (109.5 cm)
- Weight (gun only): 77.6 lbs (35.2 kg)
- Barrel: 40 mm bore with flash hider at muzzle
- Feed System: Disintegrating metallic link belt; ammunition fed from left side in belt cans (32- or 48-round belts)
- Charging Handles: Dual charging handles located at the rear of the receiver; both must be pulled simultaneously to chamber the first round
- Trigger: Single trigger mechanism with safety
- Mounting Points: Designed for MK64 cradle mount or various vehicle ring mounts
- Ammunition Cans: Belt boxes holding 32 rounds (42 lbs / 19 kg) or 48 rounds (60 lbs / 27 kg)
- Sighting: Leaf-type rear sight graduated to 1,500 meters; can accept AN/TVS-5 night vision sight
- Color/Finish: Matte black or dark olive drab parkerized finish
7. Fuzing Mechanisms
The Mk 19 launcher does not contain a fuze; fuzing is integral to the individual 40×53 mm grenades it fires:
- Operating System: Blowback-operated; fires from an open bolt. Chamber pressure from each fired round loads and re-cocks the weapon automatically.
- Firing Sequence: When the trigger is pressed, the bolt closes, and the firing pin is released. Recoil blows back the bolt, feeds a new round onto the bolt face, and pushes the expended casing off the bolt face.
- Primary Ammunition Fuzing (M430 HEDP):
- Point-detonating impact fuze
- Arms after a safe separation distance from the launcher
- Functions on impact with target
- Training Ammunition: M385I/M918 Training Practice rounds use inert or reduced-effect fuzes
- Dummy Rounds: M922/M922A1 dummy rounds contain no energetic components and are used for function checks and training
8. History of Development and Use
Development of what would become the Mk 19 began in 1963 at the Naval Ordnance Station in Louisville, Kentucky. The initial requirement was for a weapon to provide devastating firepower for riverine patrol craft operating in the waterways of Vietnam. The first attempt was the Mk 18, a hand-cranked multiple grenade launcher that proved limited in capability.
In 1966, the need for more firepower inspired the development of a self-powered 40 mm automatic weapon designated the Mk 19 Mod 0. This initial model was crude and judged to be neither reliable nor safe enough for military service. Product improvements beginning in 1971 led to the Mod 1 in 1972, of which approximately 1,000 were produced. The Mod 1 performed effectively on Navy riverine patrol craft in the Mekong Delta, demonstrating the concept’s viability.
The Mod 2 (1974) was an attempted lightweight version that never worked properly and was abandoned. In 1976, a complete redesign resulted in the Mk 19 Mod 3, which addressed the reliability, safety, and maintainability issues of earlier models. The US Navy type classified the Mod 3 in 1981, and the US Army adopted it in 1983, recognizing its potential far beyond the riverine environment.
The Mk 19 saw major combat deployment during Operation Desert Storm in 1991, where it proved devastating against Iraqi infantry and light vehicles. It has since been extensively used in operations in Afghanistan and Iraq, becoming a standard vehicle-mounted weapon on HMMWVs, MRAPs, and other platforms.
Despite multiple attempts to develop a replacement — the XM307 ACSW was cancelled, and the Mk 47 Mod 0 Striker has only been purchased in limited numbers by USSOCOM — the Mk 19 Mod 3 remains the standard automatic grenade launcher across the US military. Its reliability, lethality, and versatility across multiple mounting platforms continue to make it an essential weapon system.
9. Technical Specifications
| Specification | Detail |
|---|---|
| Caliber | 40×53 mm |
| Length | 43.1 in (109.5 cm) |
| Weight (gun only) | 77.6 lbs (35.2 kg) |
| Weight (gun + cradle + tripod) | 137.5 lbs (62.4 kg) |
| Muzzle Velocity | 790 ft/s (241 m/s) |
| Bore Diameter | 40 mm |
| Maximum Range | 2,212 m (2,419 yds) |
| Maximum Effective Range | 1,500–1,600 m |
| Minimum Safe Distance (training) | 310 m |
| Minimum Safe Distance (combat) | 75 m |
| Cyclic Rate of Fire | 325–375 rounds/min |
| Rapid Rate of Fire | 60 rounds/min |
| Sustained Rate of Fire | 40 rounds/min |
| Elevation Range | -70° to +70° |
| Feed System | Disintegrating metallic link belt |
| Operating Principle | API blowback, open bolt |
| Cooling | Air-cooled |
Compatible Ammunition:
| Round | Type | Effect |
|---|---|---|
| M430 / M430A1 | High-Explosive Dual Purpose (HEDP) | 5 m kill radius; 15 m wound radius; penetrates 2 in (51 mm) RHA |
| M383 | High-Explosive (HE) | Blast and fragmentation |
| M385I / M918 | Training Practice (TP) | Blue-tipped; reduced effect |
| M922 / M922A1 | Dummy | Inert; function checks and training |
10. Frequently Asked Questions
Q: Why can’t you use M203 ammunition (40×46 mm) in the Mk 19? A: The Mk 19 uses 40×53 mm high-velocity ammunition, which develops significantly higher chamber pressure and muzzle velocity than the 40×46 mm low-velocity ammunition used in the M203/M320. The two cartridge types are dimensionally different (the 40×53 mm case is longer) and are not interchangeable. Attempting to fire the wrong ammunition type could result in a catastrophic failure. This is a critical safety distinction for all personnel handling 40 mm ammunition.
Q: Why does the Mk 19 use the Navy “Mk” designation rather than an Army “M” designation? A: The Mk 19 was originally developed by the US Navy’s Naval Ordnance Station in Louisville, Kentucky, for riverine warfare applications. Even though it is now more commonly associated with the Army, it retains its original Navy-style “Mk” (Mark) designation from its development lineage.
Q: How does the Mk 19’s blowback operation work? A: The Mk 19 fires from an open bolt. When the trigger is pressed, the bolt moves forward, chambers a round, and the firing pin initiates the cartridge. The chamber pressure from the fired round blows the bolt rearward, which simultaneously ejects the spent case, strips a new round from the belt, and cocks the weapon for the next shot. This open-bolt design also prevents cook-offs, as no round sits in a hot chamber between shots.
Q: What platforms can the Mk 19 be mounted on? A: The Mk 19’s relatively low recoil and comparatively light weight have allowed it to be adapted for numerous platforms, including the M3 ground tripod, HMMWV ring mounts, M113 APCs, LVTP7A1 AAVs, M88A1 recovery vehicles, MRAP vehicles, small attack boats, and fast attack vehicles. It can also be mounted in remote weapon stations such as the Kongsberg Protector.
Q: Why hasn’t the Mk 19 been replaced despite being decades old? A: Several replacement programs have been attempted. The XM307 ACSW promised significant weight reduction and advanced fire control but was ultimately cancelled. The Mk 47 Mod 0 Striker has been purchased in limited quantities by USSOCOM but has not been adopted for general service. The Mk 19 Mod 3’s proven reliability, lethality, and established logistics chain make it difficult and expensive to replace across the entire force.
Q: What are the crew requirements for the Mk 19? A: The Mk 19 is classified as a crew-served weapon, typically requiring two personnel — a gunner to aim and fire, and an assistant gunner to manage the belt feed and help with ammunition handling. While it can be operated by a single individual (especially when vehicle-mounted), the weight of the weapon and ammunition makes a two-person crew optimal for sustained operations.
Q: What is the most significant UXO hazard from Mk 19 employment? A: The M430 HEDP round contains both a shaped-charge liner and a fragmentation body with an impact fuze. Unexploded rounds (duds) that have traveled beyond the arming distance will have armed fuzes and should be treated as extremely sensitive to disturbance. Given the high cyclic rate of the Mk 19, engagement areas may contain numerous unexploded rounds, particularly in soft terrain where impact forces may be insufficient to activate the fuze.