Mk 19 Grenade Launching Machine Gun

By Peter Suciu
Posted in #Guns #History
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Mk 19 Grenade Launching Machine Gun

January 27th, 2024

8 minute read

The late comedian George Carlin, when not discussing profanity or daily life, offered a very insightful view on flamethrowers. “The very existence of flamethrowers proves that sometime, somewhere, someone said to themselves, ‘You know, I want to set those people over there on fire, but I’m just not close enough to get the job done,’” Carlin famously offered.

The image shows a U.S. Army soldier firing the Mk19 automatic grenade launcher during a training exercise in Indiana. The Mk19 is a belt-fed, crew-served automatic weapon that launches 40mm grenades at the enemy. Also known as 40 mike mike, these rounds come in a variety of packages including high-explosive and anti-armor. These weapon systems are dual-purpose, allowing for both direct and indirect firing of 40 mm rounds. They are used by the Army and Marine Corps.
A U.S. soldier fires the Mk 19 automatic grenade launcher during training at Camp Atterbury, Ind. The current administration pledged 1,200 launchers to Ukraine. Image: Maj. Dan Marchik/DoD

His view could easily translate to grenade launchers. There have long been bombs that could be thrown for centuries, but only star athletes like Ty Cobb or Tom Brady could hope to throw a handheld grenade the distance to blow up “those people over there.”

That is where grenade launchers come in.

In this photo you can see multiple grenade explosions as U.S. Marines train with the automatic grenade launchers at Camp Lejune, North Carolina. Infantry Marines need regular training to stay sharp. These troops are part of the 8th Engineer Support Battalion. 
Marines train with the Mk 19 during a night fire grenade training exercise at Camp Lejeune in 2013. Image: Lance Cpl. Sullivan/U.S. Marine Corps

The concept was born with early hand mortars, which took a certain level of bravery to even employ, as the system involved igniting a fuse on a projectile that could just as easily explode in the barrel.

The Early Grenade Launchers

The first true grenade launchers evolved significantly during the First World War when there was very much a case of wanting to try to blow up soldiers across no man’s land. While artillery could do the job at a macro level, grenade launchers were in essence about targeting the enemy on a micro level.

Shown in this rare photograph is a Hales rifle grenade No. 3 in the hands of a British soldier. The soldier is in a front line trench somewhere in the Balkans during World War I. A wooden case of additional grenades is in front of him. His rifle is on a bipod which was specific to the launcher.
The British developed an early rifle grenade called the Hales. Several versions of Hales rifle grenades were developed an used in World War I. Image: Keystone View Co./Western Front Association

The initial grenade launchers began as crossbows, catapults, and spring guns — but that evolved into rifle grenades. It allowed an infantryman to use a modified rifle to launch grenades in advance or even during an attack at ranges that even Brady’s arm couldn’t deliver. The downside of rifle grenades was that it required the soldiers to mount the grenade to the muzzle, but it remained the standard method of grenade launchers for decades.

This photo shows a U.S. Army private practicing with a rifle grenade prior to shipping out to the Western Front. The United States used the V.B. rifle grenades and launchers for the Model 1903 and Model 1917 bolt action rifles that were standard issue to American soldiers. These rifle grenade launchers attached to the muzzle of the rifle barrels to provide extra range as compared to thrown hand grenades.
A U.S. Army soldier practices a rifle grenade attack from a foxhole at Fort Riley, Kansas in July 1918. Americans used the French-designed V.B. rifle grenades in the First World War. Image: NARA

This led to the development of stand-alone launchers, which were essentially firearms designed to fire specially designed ordnance, followed by attached launchers that were positioned under the muzzle of a rifle. This provides the modern warfighters with both their standard rifle while offering the ability to deliver a grenade when the need calls.

Enter the Mk 19

However, even as weapons such as the M203 arguably “got the job done,” the U.S. military still saw a need to truly send the grenades down range with a rate of fire and to a distance that was simply unprecedented. What it needed was a platform that was akin to a machine gun-styled grenade launcher — and thus was born such a weapon as the Mk 19.

Shown is the Mk19 on a white background. The weapon system delivers high-volume fire into an engagement and allows for indirect fires from hidden positions. A Marine Expeditionary Force may not have heavy artillery available, so this provides a great deal of flexibility. Marines can use it to fire on suspected enemy positions in a quicker, more accurate way than traditional mortars can.
The Mk 19 automatic grenade launcher is not easy or quick to move in the field. However, it provides a great deal of close infantry support that makes it a valuable weapon. Image: DoD

Development of the 40mm belt-fed automatic grenade launcher actually began during the Vietnam War to provide sustained heavy fire for infantry and other military personnel. At the time, the U.S. military was seeking to find a replacement for the Mk 18 Mod 0, a 40x46mm launcher, that was also the last known hand crank-operated firearm adopted by the U.S. military.

Shown is a American Navy sailor in a Tiger Strip pattern camo uniform loading a Mk18 Mod0 grenade launcher. The U.S. Navy SEALs used them on Patrol Craft Fast (PCF) boats (also known as Swift Boats) for additional firepower when patrolling the rivers and costal areas during the Vietnam War. 
The Mk 18 Mod 0 was a hand-cranked, belt-fed grenade launcher. Here a U.S. Navy sailor readies one for action on a patrol boat on a Ca Mau Peninsula river. Image: PHC A. R. Hill/U.S. Navy

That platform, though effective enough that it was employed by the so-called “river rats” and U.S. Navy SEALs in Southeast Asia, was limited by its short effective range of just 375 meters (410 yards). 

The Mk 19 was essentially as much of a leap forward as the Browning Model 1917 machine gun had been from the hand-cranked Gatling Gun. The weapon was designed at the Naval Ordnance Station in Louisville, Kentucky, in 1966. It was introduced in 1968, and first saw combat with the U.S. Special Operations Forces, mounted on vehicles, boats, or on a tripod.

This photo shows the XM174 automatic grenade launcher in the Vietnam War. The XM174 was a forerunner to the Mk 19, but it suffered from a variety of issues including limited ammunition and was prone to breaking. The system used 40mm grenades like the M79 and was sometimes called the automatic M79. It used the fire control system from a M1919A4 machine gun.
Near Da Nang, Pfc. John T. Wiseman aims his XM174 grenade launcher. This mashup of a M79 Thumper and M1919A4 was a forerunner of the Mk 19. Image: Lance Cpl. John Gentry/U.S. Marine Corps

Though it is technically a grenade launcher, it is also essentially an air-cooled, blowback-operated, belt-fed machine gun that fires 40mm high explosive dual purpose (HEDP) ordnance. As the Mk 19 fires from an open bolt, and can maintain a low barrel temperature during rapid fire, the rounds cannot “cook off,” yet it has a sustainable cyclic rate of 325 to 375 rounds per minute — although the effective rate of fire is 60 rounds per minute, with a muzzle velocity of 790 feet per second.

It is noted for having a weapon life exceeding 50,000 rounds, whilst mean rounds between failures exceed 20,000 rounds. As a grenade-type weapon, the minimum range is about 80 yards for the safety of the operator and friendly personnel.

Machine Gun-Style Dominant Firepower

It is noted for being able to dominate a space at short and long-range distances with continuous firepower. When employed on the battlefield, the Mk 19 grenade launcher — which is equipped with Maxim machine gun-style spade grips that provide stable control — is capable of delivering lethal fire against a variety of targets, including lightly armored vehicles and dismounted infantry out in the open, in defilade, or in entrenched fighting positions.

Shown is a pair of Marines shooting a Mk-19 grenade launcher during training in Japan. They are wearing their green camo utilities and helmets with full body armor. There is a hill in the background, green grass everywhere and a bright blue sky.
A Marine crew in Okinawa, Japan, fires a Mk 19 automatic grenade launcher on the Kaneohe Bay Range Training Facility in March 2014. Image: Lance Cpl. Matthew Bragg/U.S. Marine Corps

As an infantry weapon, the Mk 19 automatic grenade launcher is typically mounted on a robust tripod that isn’t all that different from the U.S. military’s mount for the Browning .30 caliber or .50 caliber machine guns. As with those machine guns, it normally requires a crew of two — with one managing the firing and the other facilitating the belt feed.

Versatile and Effective 

As the platform is also noted for its low recoil and comparatively light weight of just 77.6 pounds and compact size (43.1 inches in length, the Mk 19 has been adapted for use on a variety of platforms, including small attack boats and fast attack vehicles, such as the Humvee (HMMWV), AAV and Stryker, as well as a large variety of naval mounts.

In this photo, a line of U.S. Marine Corps armored vehicles are engaged in a live fire training in the snow. 
Marines with the 4th Marine Division fire mounted MK-19 grenade launchers at Camp Ethan Allen Training Site in Jericho, Vt. in 2018. Image: Pfc. Samantha Schwoch/U.S. Marine Corps

The Mk 19 can be employed to effectively engage point targets up to 1.5 km (1,600 yards), while it can be used to strike area targets at distances up to 2,212 m (2,419 yards). It is also outfitted with a flip-up leaf rear sight for “precision” fire, marked to 1,500 yards.

The 40mm HEDP round can penetrate 75mm rolled homogenous armor at its maximum range, which means it can penetrate most infantry fighting vehicles and armored personnel carriers. When used against dismounted personnel, it has a kill radius of five meters against infantry, and within a radius of 15 meters enemy troops on the ground will be immobilized by blast and fragmentation.

This photo shows US troops in training in Afghanistan. Outside his joint combat outpost in Baghlan province, Staff Sgt. Adam Tackett, the platoon sergeant for 1st platoon, Blackfoot Troop, 6th Squadron, 4th Cavalry Regiment, 3rd Brigade Combat Team, 1st Infantry Division trains Spc. McDonald on the MK19 grenade launcher. Sgt. Nicholas King, a section sergeant in 1st platoon watches the rounds impact downrange. The 6th Squadron, 4th Cavalry Regiment, 3rd Brigade Combat Team, 1st Infantry Division, from Fort Knox, Ky., in support of Operation Enduring Freedom.
Outside their joint combat outpost in Baghlan province, Afghanistan, U.S. soldiers train with the Mk 19. Image: U.S. Army

Perhaps one area where the Mk 19 did come up short — at least compared to the aforementioned M1917 machine gun — is that the 40mm ammunition (40×53 mm) is not interchangeable with the ordnance for the M203 (40×46 mm) under-mount grenade launchers used by the U.S. military. At issue was that the M203 round develops a lower chamber pressure, and resultant lower muzzle velocity and range.

To date, the difference in ordnance hasn’t resulted in any supply issues on the battlefield, however.

Mk 19 Grenade Launcher in Combat Operations

The Mk 19, which is currently produced by General Dynamics Ordnance and Tactical Systems, has been upgraded and will likely remain in service with the U.S. military for years to come. Much like John Browning’s machine gun designs, it would be hard to significantly improve upon the platform.

The image shows members of the Qwat Khasa, Iraqi army, work together to engage targets with a Mark 19 40 mm grenade machine gun at the Besmaya Range Complex, Iraq, Jan. 24, 2018. Training at building partner capacity sites is an integral part of Combined Joint Task Force — Operation Inherent Resolve’s global Coalition effort to train Iraqi security forces personnel to secure and stabilize their country and deter the resurgence of ISIS.
U.S. soldiers teach Iraqi soldiers how to operate the Mk 19 “grenade machine gun” in 2018. Image: Master Sgt. Horace Murray/U.S. Army

There have been attempts to develop additional ordnance for the Mk 19 — including an airburst grenade that employs a programmable, time-based fuse. Such rounds could provide greater effectiveness and lethality to what is already an extremely effective and deadly weapon.

To date, more than 35,000 Mk 19 Mod 3 systems have been produced since the middle of the 1980s, and it has been employed with U.S. allies and partners around the world. The grenade launcher has been adopted by several NATO members and was produced under license in Egypt, Israel, and South Korea. In Israeli service, it was produced under the name “Maklar,” short for mikla rimonim or “grenade machine gun.”

Pvt. Jasmin Camacho and Pvt. Kossi Atsidama, human resource specialists, assigned to 90th Human Resources, Special Troops Battalion, 3rd Division Sustainment Brigade, conduct an MK19 range on Fort Stewart, Georgia, Jan. 21. Soldiers conducted the range as part of 87th Combat Sustainment Support Battalions weapons density to ensure that Soldiers build proficiency with cruiser weapon systems.
Soldiers of the 90th Human Resources, Special Troops Battalion, 3rd Division Sustainment Brigade train with the Mk 19 at Fort Stewart, Georgia. Image: Spc. Elorina Charles/U.S. Army

Though it was first employed in Vietnam, the Mk 19 proved to be well-suited to the rugged terrain of Iraq during the 1991 Gulf War and was used in the Global War on Terror (GWoT) throughout the world — serving with U.S. and partners in conflicts in the Middle East and Africa. It has also been employed by the Mexican Army in its ongoing conflict with the drug cartels.

An unknown number of the Mk 19 grenade launchers were supplied to the Afghan Army before the U.S. withdrawal in August 2021. Those were subsequently captured by the Taliban, which has continued to employ the weapon in its war with ISIS-K. 

The image shows Sergeant Oscar Mena fires a Mk-19 40mm grenade launcher during a crew-served weapons familiarization shoot for Battalion Landing Team 3rd Battalion, 5th Marines, 31st Marine Expeditionary Unit, Aug. 20, 2014. 
Sgt. Oscar Mena fires an Mk 19 40mm grenade launcher during a crew-served weapons familiarization in 2014. Image: Cpl. Henry/U.S. Marine Corps

To date, it remains unclear if Afghanistan has been able to produce the 40mm HEDP rounds locally — but Iran managed to keep U.S. military hardware operational for decades after its 1979 revolution, and it also has continued to operate a number of Mk 19s that were supplied in the 1970s. Fortunately, the Islamic Republic was never able to replicate the platform with any success, but Afghanistan — which has copied firearms for centuries — could have better luck… .

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Peter Suciu

Peter Suciu

Peter Suciu is a Michigan-based freelance writer who regularly covers military history and hardware for The National Interest and FoxNews. He has collected military small arms and headgear since he was 12 years old. His most recent book A Gallery of Military Headdress was released last year and is available from here.

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