Art Pizza dedicated more than 38 years serving the U.S. Army in its Armament Research, Development and Engineering Center (ARDEC) (which is now known as the Combat Capabilities Development Command, Armaments Center) at Picatinny Arsenal. In that time, he spent 17 years as a project engineer on the Mk19 grenade machine gun. He spent five years on the Green Ammo project (5.56mm and 9mm). Then he became the center’s Technical Expert on 40mm ammunition. He later went back into design and became the ARDEC Project Officer on hybrid ammunition (including mortars) and the extended range guided 40mm projectile. Pizza spent the last five years before his retirement as the Project Integrator for Medium and Small Caliber Weapons, Ammunition, and Fire Control systems.

We sat down with Pizza to discuss his long and distinguished career.

Small Arms Defense Journal: Art, thank you for your service to the U.S. Army and the 40mm weapon platforms. We greatly appreciate you taking the time to connect with Small Arms Defense Journal. You have the unique perspective of spending significant time in both 40mm weapons and 40mm ammunition. To solve the age-old question – when there is a system failure, who’s usually to blame, the ammo guy or the weapon guy?

Art Pizza: Around the late-1970s or early ‘80s, when the U.S. Army transitioned the Mark19 40x53mm weapon from the Navy, they were hand fitting/gunsmithing each weapon making 3-7 guns a month at Navy Ordnance Station in Louisville, Kentucky. They were beautiful, hand-built weapons; however, the production numbers were nowhere near the rate the Army needed. The Army was looking to make over 250 weapons a month. They end up contracting to Saco Defense (now General Dynamics Saco, ME). The complete Technical Data Package needed to be reworked. They worked closely with Saco Defense in manufacturing the weapon and improving the mass production and tolerances to make it at a high production rate weapon.

At the same time, we needed to increase the production rate of 40mm High-Velocity ammunition. The Mark19 is an advanced primer, blowback-operated weapon in which the bolt never locks into the receiver and depends on the firing pin tripping as the heavy bolt is moving forward. The velocity of the bolt moving forward is critical to the functioning of the weapon. The contracted 40mm ammunition at that time was purchased as individual components and sent to Milan AAP for final load, assembly and packing into cartridges. Most of the issues pertained to the consistent crimping of the cartridge case (a new 360-degree roll crimp vs. the old, staggered stake crimp.) Unfortunately, the failure to obturate because of the crimp issues caused stuck projectiles in the Mark19. If a second round was fired into the first projectile, on rare occasions it could cause a low-order explosion. This was called an in-bore detonation.

Other ammunition issues early on were related to improper charge weight. They old systems were using a volumetric charge measurement system. These cartridges also often had missing or double copper closure cups, and material flaws in the aluminum cartridge cases. We were looking to increase the production of ammunition from 40,000 units a year to close to 1 million. The solution was to have completely automated loading with net-weight, check weight systems and liner voltage distance transducers (LVDTs) to have a machine check for presence and location of these items.

Mark 19 issues mainly pertained to the timing of the feed system on the weapon resulting in dropped rounds and what we called at the time banana cartridges (because they would get bent by the weapon). Both caused feeding issues and could cause a lodged projectile or even a dropped round. The Mark19 represented new challenges to the infantry in the form of a high explosive machine gun in a small package of 65 pounds. Another issue was using the right lubrication in the field. The Mark19 called for LSAT lubricant, which was in short supply. A lot of feeding issues were based on a lack of adequate lubrication or lubrication not in the right location on the receiver rails or feed tray. Every gun coming out of the Saco factory was function fired for firing rates. If I remember right, we fired three guns 50,000 rounds each for endurance testing each year.

The bottom line was that most of the early stoppages were attributed to ammunition. Improvements to modern manufacturing methods and inspection reduced these to almost non-existent in the early stages. The weapon went through changes, as well. The cocking lever was modified to a two-piece design that reduced the possibility of an out-of-battery firing. Lubrication became more prevalent, and attention was spent on the timing of the feed system. If you had a problem with the Mark 19, it could usually be attributed to either the feed shuttle timing, a dirty weapon, or a broken part. One time I was called in to look at some weapons having issues. It turned out they did not have LSAT lube and were instead using WD40 and Break Free. They would run through maybe a box or two of ammo (32 to 64 rounds) before the gun stopped. We brought one tube with us, and we painted it on using a paintbrush to get through the training until a supply was sent in.

Over time, I was involved in several malfunctioning investigations and would try to get on-site within 48 hours. As an infantry weapon, we were not doing round counts (of how many rounds had been fired through the weapon) so we would never know what to expect, especially at training locations. I would say 80% were attributed to ammunition. If you are making over 1 million rounds a year, it is possible to get one or two bad rounds. The fuses were made back then at KDI and were difficult to manufacture but had double safeties (spin and setback). Most in-bores were attributed to a low order detonation from a round striking a stuck projectile lodged in the barrel.

Therefore, to answer your original question in the 40x53mm platform, at that time, it would have typically been the ammunition guy causing the problem.

SADJ: As an ammo guy, I will humbly accept the criticism. As far as the rest of the story, all I can say is wow! That is an amazing summary of decades of work. Over the course of your nearly 40 years in 40mm, what do you feel was your greatest accomplishment?

AP: The transitioning of the Mark19 to the Army and the rework of the technical data package. Getting it into full-rate production and fielding to the U.S. Army was a terrific feeling. Seeing what you worked on and talking to soldiers about the use of it in combat and how it saved their lives meant a lot to me. I met with some soldiers that were involved with the rescue mission of the “Black Hawk Down” incident in Somalia. The largest weapon they had available on the ground was two or three Mark19s mounted on HMMWVs. They were using it as an anti-sniper weapon and fire was directed by a captain using a laser pointer. The captain talked about the leveling of a hotel in Somalia that was stopping their rescue attempt and which they were receiving heavy fire from. The Mark19 took down the entire building. Knowing what we did at ARDEC saved a lot of U.S. lives, and knowing it was instrumental to the rescue operations, made it all come together for me. I still remember talking to this captain about what the Mark19 enabled him to do. It was hard not getting teary-eyed for him and me while listening to his story.

SADJ: Looking back over your career, was there a particularly fun project that you remember?

AP: The Extended Range Guided 40x46mm cartridge (EGR40) was the most fun. This projectile was for the handheld M79, M203, and the M320 low-velocity 40mm weapon. I was the technical expert for some time in 40mm ammunition engineering and I was asked if I wanted to lead a design team in the development of the early R&D effort. It was an easy choice going from riding a desk to getting back into a real hands-on engineering development project.

My senior design engineer, Ronny Alzamora, and I designed a new finned projectile and cartridge case with an improved combustion chamber. We had a team of engineers working on guidance navigation and control, camera, transmitters, laser receptor, and also working on wings and canards. Every week we were cutting metal and going to the range firing projectiles. It was all hands-on design work which you just didn’t usually see in the government. We had between 20 and 40 people working on various parts of it, along with a contractor and universities. We even did some early work with some students from West Point as a capstone project. We also looked at a rocket assist system. It was a lot of work. We pushed the envelope… a lot. We worked the engineers very hard. I was very lucky to have had that opportunity and it was a lot of hard work getting the separate teams focused on the end game. I learned a lot about human relationships and forming a team.

SADJ: What project was the most challenging?

AP: It was, by and large, the EGR40 because of the hands-on work we did.

SADJ: Are there any projects that you wish you could’ve had a second chance at it?

AP: What we learned about the LV 40x46mm, we never got a chance to put into practice. We found that course correction could not be accomplished in the time of flight and was not enough to make a difference at impact. We did successfully put a camera in the projectile, survive launch, and transmit and receive video and course correction signals. What we did learn was that the current 40mm round is spin-stabilized and lost spin and wobbled, making it difficult to hit a target at 400 meters. When we made our fin-stabilized projectile, we were more accurate out to 600 meters and had some variations that we were able to fly to 1,000 meters. Toward the end of the R&D project, we were pushing to drop the guidance (wings and canards) and convert to just a tail-fined projectile that had the ability to double the range of the standard HEDP projectile. We were able to increase HE and fragmentation by designing a new larger warhead. We could not get the funding to pursue this option and the team was dispersed. They tried to make improvements to the existing spinning projectile but could not demonstrate any major improvements with a spinning projectile. A finned projectile is more accurate and will fly further than a spin-stabilized one.

SADJ: Are there any other areas of your work that you would like to share with our readers?

AP:What we (Army Engineering) do has an impact on soldiers’ lives even if we don’t know about it. Don’t believe that it can’t be done. So many times in my career I was told that this or that wouldn’t work. I was told we would never get a camera to survive a gun launch. We were told we would not be able to transmit a clear image. You have to look at new innovative ideas and methods. Modeling, simulation, and design of experiments are the keys to success. You have to get away from the build-and-break mentality and think about the design of experiments. You need to test statistically with multiple variants to reduce iterative designs. Design decisions are made on statistical-based results.  

SADJ: Can you paint of picture of what the 40mm systems families will look like 40 years into the future?

AP: What I envision for a 40mm low-velocity grenadier M203/M320 weapon:

• 1-2 camera rounds with a GPS location that will transmit enemy positions back. Detect behind berms, buildings, or in defilade.
• Several extended-range projectiles with a higher velocity and flatter trajectory with increased range out to 1,000+ meters. Finned projectile with improved warhead and increased lethal radius.
• Several HE dual purpose projectiles with improved armor penetration.
• Possible netted projectile or an airburst anti-UAV projectile
• Specialty blast overpressure round for room clearing or tunnels.
• Specialty non-lethal projectiles.
• Specialty flechet round for room clearing. HEDP is useless in urban areas, room clearing, etc.
• Specialty door breaching projectile (may be able to do this with a blast overpressure).
• An improved fire control system that would allow the rounds to take on a semi-mortar-like role.

And, for the Mark19 High-Velocity system:

• A camera round that can be used for GPS and intelligence. These rounds will be able to provide intelligence out to 2000 + meters.
• An anti-UAV projectile; blast overpressure, net, etc.
• Flechet round for urban areas.
• Flare rounds, including IR flares, with higher altitudes and longer burn time. These are not currently in the HV systems. This would give night vision extended range.
• Improved cartridge case hemispherical powder chamber.
• Extended range, fin-stabilized rounds for ranges over 2,000+ meters.
• Improved fire control system to allow indirect fire applications.

By Jay Bell

Sometimes what appears to be a good idea is not as good as it seems. That appears to be the case in the 40mm training ammunition world. The U.S. Army’s 40mm Day/Night/Thermal (DNT) effort has stalled and then restarted on the high velocity (M918E1) and on low velocity (M781E1) but has not successfully completed the First Article Acceptance Test (FAAT or FAT). These rounds were supposed to be a major leap in technology. They achieved several key requirements of the U.S. government. The Army got rid of a troublesome fuze in high velocity and added night training capability in low velocity in order to train like soldiers fight, at night. The magic material that made all this happen is called “pyrophoric iron.” Pyrophoric iron spontaneously combusts when exposed to air. It turns out that the pyrophoric iron may not be all it was cracked up to be. It has some serious downsides: It causes range fires, and allegedly, at least one round has gone off prematurely, flashing at 3,000 degrees with the gunner inches away.

Going Back

Now, the U.S. Army appears to be going back to decades-old technology to address the training requirements for the 40mm MK19 machine gun and M320/M203 weapons. The training ammunition for these platforms goes back to the later 1960s. The Army recently made an award to go back to the M918:M385 2:1 Mixed Belt configuration in December 2019. There was also a “Sources Sought” notice that came out in November 2019 to re-ramp for the projectiles, which were shelved a few years ago. The main producer had an auction in July 2019, since the DNT rounds appeared to be the path forward.

The Sources Sought announcement officially kicks off the procurement process for a 5-year “Indefinite Delivery Indefinite Quantity” contract to buy these 1960s technology, high-velocity projectiles. The high-velocity and low-velocity images are the old school rounds—a cutaway of the M918 Flash Band smoke and the M781. These images are courtesy of the U.S. government, and the comments are from one of the early Industry meetings highlighting the deficiencies circa 2014. Images of the M918E1 and M781E1 show only the outside of the new rounds. The insides are not available for public consumption. I attempted to get pictures from the Army, however, due to all the issues with the 40mm E1s, they were not letting any more pictures out. However, all of the market intelligence seems to point back to the 2004 Ted Haeselich patent, with chemical glow stick material in the middle of the round contained in a glass ampule (numbered 21/22). This ampule breaks and mixes upon setback to give a “lava” spurt downrange at night upon impact. The #13 item would be the standard orange powder or “signal dye.” This is to signal the impact area of the round.

Original U.S. government program timeline for the DNT program (see 2013).

A Little History

Since the 1990s, the 40mm high-velocity training ammunition option has been less than desired by the U.S. military. The 40mm M918 “flash, bang and smoke” round had multiple issues:

1) It had an expensive fuze that did not always function as desired and especially had problems in soft range conditions—sand, mud, wet, etc.

2) The fuzes did not have a self-destruct feature.

3) Projectiles that did not function are “unexploded ordnance” UXO and could cause injury if kicked or picked up.

4) The M918 was known to cause range fires that would shut down the training activities in some environments.

5) The M918 had a higher hazard storage and transportation class for the round.

The USMC became so fed up with the M918 situation that in the 1990s it stopped buying the Army’s M918 and started buying the MK281 from a small German company called NICO. The MOD 0 version had an orange signal dye like the Army’s low-velocity M781. Ted Haeselich worked at NICO in the 1990s and into the early 2000s. After an extensive adventure to fully type-classify the round, costing hundreds of thousands of dollars, the USMC made large purchases of the MK281. Later when NICO was purchased by German Military giant Rheinmetall, Rheinmetall started a U.S. manufacturing facility, and the orders skyrocketed. The original contracts to Germany were around $30M, and once they had the U.S. final assembly included, the contracts shot up to the $300M range. The story is a legend in the defense community.

Ted Haeselich’s patent with chemical glow stick material in the middle of the round contained in a glass ampule (numbered 21/22).

The MK281

The MK281 was perfectly simple. Basically, it is a high-velocity M781. It had a proprietary propulsion design that threads the projectile to the cartridge. The round must shear metal to fire, which is much more consistent than crimps and adhesives. The results are greater accuracy downrange. Later versions of the round added chemical luminescence aka glow sticks, to give a nighttime impact signature. It did not have a fuze, so there was ZERO chance of a dud. An additional plus is that the chemical luminescence materials are totally safe, ala Halloween glow sticks for kids. It can be eaten by kids on Halloween, and they can still eat all the candy they can handle. To meet the requirement of the DNT, the chemical properties were adjusted to add more heat to the process to be picked up with thermal imaging. The chemicals can be tweaked for colors, brightness, duration of glow and heat output.

The German cartridge design is favored by a lot of military forces around the world. Due to some old conflict over patents, the desire for 100% American-made products and a few other reasons, the MK281 has never seen full acceptance in the U.S. It does have one drawback, the chemical luminescence glows a rather long time. When you are training at night and shoot a large number of rounds, say 50 to 100, the target area will end up glowing so much that it is hard to tell when the last round hit. This phenomenon was coined as washout.

The Army Plan

The U.S. Army’s Project Manager Maneuver Ammunition Systems (PM MAS) started the planning for this next wave of development a long time ago. The 40mm DNT Industry Days date back to the early 2010s. The U.S. Army’s competition to solve its need for an improved M918 would be the M918E1 and in low-velocity M781E1. The M918/M781E1s had several key requirements:

1) No or minimal range fires (M918 only);

2) No fuze to fail and reduce costs (M918 only); and

3) Day, Night and Thermal visibility and/or signal (both rounds–new for M781).

PM MAS would have companies compete for the prize of making the rounds. The winning design would get the initial multi-year development contract and be in the leading position to make the rounds for the next 50 years. The M430 effects are the visual effects from an M430A1 HEDP round at 500m. The Army wanted a similar nighttime effect as seen in night vision.

On to the Competition

Nine companies submitted bid samples for evaluation in both 40mm high-velocity and low-velocity versions. These companies spent millions of combined dollars to get their designs mature enough to withstand the rigors of DOD testing. This field included American Ordnance (AO), Amtec, Chemring Ordnance, Cyalume Technologies, General Dynamics (GD), Rheinmetall, ST Kinetics (Singapore) and Universal Defense. Some did not even make it to the testing phase; some failed out early in testing.

These nine were down-selected to two competitors for high velocity—Amtec and AO Ordnance—and two for low velocity—Amtec and GD. Would the 40mm powerhouse Amtec, continue to dominate the 40mm world? Or would the large businesses with their success in ordnance in AO and general small/medium caliber ammunition expertise allow GD a win? Ultimately, it was AO as the high-velocity winner and GD as the low-velocity winner. The MK281 was in the mix along with several other varieties; however, it did not make the cut.

The competition had several deciding elements. The most important was pyrophoric or chemical luminescence. The best attributes of pyrophoric material were: a high heat output for thermal, bright visual light/explosion for the naked eye and lower hazard for storage and shipping. The best attributes of chemical luminescence were that it was totally inert and had zero risks of range fires. The negatives for pyrophoric was the “potential” for range fires. The downside of the chemical material was that it is difficult to see at 1,200m with the naked eye and the washout effect, as described above. The winning solution ended up being a pyrophoric solution for both rounds, which appears to be a key reason the programs have had so much difficulty.

Magic Material

Pyrophoric materials are processed iron particles that are contained in a glass ampule without air. When the ampule breaks and is exposed to air, it oxidizes quickly—actually, very quickly, which results in a lot of heat and a lot of light. It is technically a flash of light; some people might mistake it for a small explosion. The waste material is iron powder. It can be thrown away without concern about hazardous waste. It’s pretty awesome. The more interesting attribute is that if you break the top of an ampule off, the material will just simmer. You would just notice a color change and a slow process happening. If you turn the ampule over, you get a sparkler light show all the way down to the ground. If you smash it against the ground at 700m per second, you are back to the explosion-like effect.

The downside of pyrophoric material and what caused the program to be placed under a temporary Stop Work order is that the rounds were causing a lot of range fires—there was a safety incidence where the round in the chamber was broken and flashed in the weapon (potentially injuring the gunner)—and other performance issues. The M918E1 has a plastic ogive, and underneath it are some pretty powerful materials. The MK281 also has a plastic ogive; however, if this round breaks in the cycling of the MK19 machine gun, the glow stick material is not going to harm anyone.

Low-Velocity Status

The M781E1 delay issues are a little less well known. GD has not made it through first article testing, where AO is in production and has been awarded option quantities already. Is it the same pyrophoric range fire issues as M918E1, or is it something else? The drop test for pyrophoric could be to blame. The standard M781 could never pass a NATO standard 1M drop test. By the look of the design, I imagine that it would still be a problem. The pyrophoric material would make things interesting if it broke upon impact.

I have always been critical of the U.S. government’s typically painstakingly slow methods and processes. They test, test again and then test some more. Then repeat all those tests in multiple temperature phases. Once you are sure you have it nailed, they have someone else try to repeat the results exactly. It can be quite maddening at times, and you wonder how anything gets done. The 40mm DNT program seemed to be moving at light speed. It was extremely impressive. This current situation has given me a greater appreciation for taking it slow. The U.S. government goes slow when one item has been changed. In this case a little more so.

Pyrophoric materials have been successfully used in other military areas like aircraft countermeasure flares. However, it is still a newer process. The processes and applicant for 40mm had to be developed and built for these programs. Sometimes plans don’t work out at well as one would have hoped. This may be the case with pyrophoric—that it is just a little ahead of its time. There are a lot of people in the industry that think the M918E1 and M781E1 are doomed to failure. They believe the range fires might result in the M918E1 and M781E1 to be shelved, and we will go back to the 1960s designs, at least for a little while, and then either back to chemical luminescence or a newer material.

M918E1 the high-velocity round reducing the UXO hazard for the U.S. government.

The government’s original timeline from a 2013 Industry Day shows the program transitioning to full-rate production over / around 5 years. In reality, it took about 6 years. If they have to go back and re-invent the wheel, it will take another 5 years. These things just take time. This is one case where too new and not enough testing set things back, maybe a decade. Only time will tell.

Until recently, the field of 40mm grenade launchers was almost exclusively dominated by the M203.  With the recent adoption of the Heckler and Koch M320 by the U.S. Army, a look back at Heckler and Koch’s legacy 40mm systems is in order.  First designed in the late 1950’s, the 40mm grenade system was a stop gap system to bridge the distance between grenades thrown by hand, and the employment of light mortars.  Hand grenades are limited by the distance the infantryman can throw the grenade, typically about 25 meters.  A mortar is capable of dropping rounds as close as 60 meters from the firing position, but the weight of the system and ammunition present logistical and load bearing issues for light infantry.  Clearly, a smaller and lighter weapon system was needed to bridge the gap.  Enter the 40mm grenade.

The HK69: the Original H&K Grenade Launcher
The HK69 grenade launcher is a stand alone, single-shot, shoulder-fired, breech-loaded weapon.  The receiver incorporates the barrel assembly, firing system, and trigger mechanism.  Configured with a rifled barrel, the barrel is hinged at the front of the receiver and rotates upward and away from the receiver, much like an over/under shotgun.  Like a shotgun, the oversized latch to the rear of the receiver (and what appears to be the weapon’s hammer) is actually the barrel release mechanism.  By pushing the barrel release latch to the rear, the barrel is unlocked from the receiver, and springs open under spring tension.   The system lacks an ejector because one is not needed; the additional engineering and weight was deemed unnecessary for a single shot weapon.  Instead, the barrel breech is cut to allow the user to pull the spent cartridge from the breech of the barrel.  This design element has continued throughout the HK 40mm system design, and can still be seen within the current M320 design.

Weighing in at 5.75 pounds, the HK69 distinguished itself from the XM148 and the M203 in that it utilized a break action, similar to a shotgun.  This design proved fruitful, and has lived on as one of the most useful designs in 40mm systems.  The M203 was limited to a round approximately 5.25 inches in length – if the round was any longer in length, the M203 receiver interferes with the loading of the 40mm round in the M203 barrel.  Unlike the M203, the HK69 has no issue accepting oversized 40mm rounds.  Because the barrel swings upwards and away from the receiver, the barrel is not obstructed by the receiver.  This design element has also continued to the present, and can be seen with slight variation within the Heckler and Koch M320 weapon platform.

The safety mechanism on the HK69 is a lever system, on the left side of the receiver, with large markings to show whether the weapon is rendered safe, or ready to fire.  The safety blocks the trigger bar from releasing the hammer; in this manner, the weapon may be safely carried loaded, hammer cocked, with the safety on.  Not one to trust mechanical safeties, potential users may consider carrying the weapon in Condition 2 (hammer down on a loaded chamber) as a better alternative.

The HK M320 mounted on an HK 417 rifle. The HK M320 is interchangeable between rifles without special mounts or hardware. (Photo courtesy of Heckler and Koch.)

The hammer on the HK69 is external to the receiver and is exposed for manual manipulation.  When needed, the hammer can be quickly cocked, rendering the weapon ready to fire.  In the event of a misfire, the weapon can be quickly re-cocked by engaging the hammer.  The trigger on the HK69 is surprisingly light.  Given the design as a single action trigger, perhaps the responsive trigger should not be surprising.  When shooting the family of Heckler and Koch 40mm weapons, the HK69 had the best trigger system, far exceeding the double action only triggers found on later Heckler and Koch systems.

The HK69 utilizes a polymer pistol grip, and a lightweight tubular telescoping metal stock.  Sling swivels are available for use with a sling.  The system is strictly a stand-alone unit, and cannot be mounted to a host weapon in the same manner as the HK79 weapon system, or other future HK 40mm systems.

Operation of the HK69
Loading and unloading the HK69 is intuitive and easy.  To open the barrel, grasp and rotate the oversized barrel release mechanism to the rear.  The barrel opens under spring tension.  Loading the weapon is as easy as dropping the desired 40mm round into the breech of the barrel.  Unloading the weapon is equally easy by utilizing the semi-circle relief cuts within the breech to grasp the cartridge base.

The weapon is cocked by retracting the hammer at the rear of the weapon.  The manual safety on the left side of the receiver should be pushed to the “fire” position.  The weapon is now ready to fire.

Two sight systems are employed on the HK69.  The first system utilizes a small, fold down blade sight capable to engaging targets at 50 to 100 meters.  For longer range accuracy, a folding ladder sight allows the user to engage targets out to 350 meters.  With a little practice and experience, it is possible to engage targets beyond the listed maximum range.

Final Analysis
Potential downsides of the HK69 included the all metal interface – the weapon seemed significantly heavier than any other 40mm grenade system, save for perhaps the HK79, when mounted to a G3 rifle.  The steel receiver has a tendency to get extraordinarily hot when exposed to desert firing conditions.  Presumably, the steel receiver would be equally cold if exposed to sub-freezing temperatures.  The same issues were not observed when test firing other systems.  Other downsides included the single-action only trigger.  Although the single action trigger was extraordinarily crisp when compared to other 40mm systems, the weapon has no provision to fire as a double action.  In the event the shooter forgets to cock the weapon, the weapon will not fire – the trigger simply releases the hammer – the trigger will not cock the hammer if the hammer is down.  Adopted by the German army in 1974, the HK69 was popular within the European community, but saw limited commercial success in the United States.  As a first generation 40mm weapon system, the HK69 is highly effective, easy to use, with the fire control mechanisms intuitive to most shooters.

The author test firing the HK 79 grenade launcher.

The H&K HK79: Competitor to the American M203
Partially based upon the HK69 design, the HK79, together with the XM148 and M203, brought significant firepower to the individual infantryman.  No longer limited to the engagement distance of hand thrown grenades, the individual infantryman could use his rifle as a mobile platform for indirect fire.  Similar to rifle grenades of World War II, the 40x46mm grenade system offered a larger payload and more advanced safety systems.  More importantly, rifle grenades of World War II relied upon blanked ammunition to launch grenades down range.  With the advent of the 40x46mm grenade systems, the individual infantry soldier could engage the enemy with a 40mm grenade with follow on fire from his rifle.  There was no longer a need for the soldier to carry ball and grenade launching rifle ammunition.

The HK79 was the German response to the M203.  Designed to be attached to German battle rifles, the HK79 was most commonly seen mounted to the G3 and HK33 model rifles, but could be adapted for mounting to most European designed rifles.  Because the system was based upon the design attributes of the HK69, there are design commonalities between the two systems.  Most notably, the HK79 is made primarily of steel, resulting in a heavy addition to any battle rifle.

The HK79 grenade launcher is a single-shot, shoulder-fired, breech-loaded weapon.  Like that HK69, the receiver incorporates the barrel assembly, firing system, and an unusual trigger mechanism.  Configured with a rifled barrel, the barrel is hinged at the front of the receiver.  Unlike the HK69, the HK79 barrel rotates downward and away from the receiver.  The practical effect however is the same – the barrel extends away from the any obstruction created by the receiver, allowing extra length 40mm rounds to be easily chambered.  Similar to the HK69, the barrel is released via an oversized latch on the left side of the receiver.  By pulling the barrel release latch to the rear, the barrel is unlocked from the receiver, and allows the barrel to open under spring tension.  Like the HK69 (and all HK 40mm systems) the system lacks an ejector – the barrel breech is cut to allow the user to pull the spent cartridge from the breech of the barrel.

Operation of the safety is achieved via a cross-bolt manual safety catch, a traditional round push through switch installed on the receiver, forward of the cocking mechanism.  The “safe” and “fire” positions are marked with red and white rings respectively; the weapon can be loaded and cocked with the safety set at either position.  Unlike the HK69, the fire control mechanisms on the HK79 are entirely different from any previous or subsequent 40mm grenade launcher.

Replacing the external hammer of the HK69 is the Hk79’s horizontal T-grip, at the rear of the receiver.  Similar in size and shape to the charging handle on an M16 rifle, the HK79 hammer is set by retracting the charging handle to the rear.  The charging handle also has the effect of resetting the trigger.  Like the HK69, the system can be re-cocked without unlocking the breech, in the unlikely event of a misfire.  In this respect, the HK79 is similar to the failed American XM148, which also used an external handle to charge the weapon.  However, the HK79 system is much more refined than the XM148 system as would be expected from German engineering.

The US Army’s programmes for developing two different 25mm grenade launchers – the shoulder-fired XM25 from Alliant Techsystems and the crew-served XM307 ACSW (Advanced Crew-Served Weapon) by General Dynamics – are probably the most ambitious small arms projects in existence.  They are meant to revolutionise the effectiveness of small-arms fire by detonating HE/fragmentation grenades directly over the target, thereby greatly increasing the number of casualties, not just of standing men but also those hiding behind cover.  Such rounds are known as HEAB (High Explosive Air Burst) or ABM (Air Bursting Munition).

To achieve this requires some sophisticated technology.  The XM307 is fitted with a day/night sight with a laser rangefinder, a ballistic computer and a fuze-setter.  The gunner first lases the target to establish the range (this can be overridden if the target is at a slightly different distance than the aiming point); the system then takes atmospheric conditions and weapon tilt angle into account before indicating the aiming mark in the sights.  The gunner can set the fuze mode for airburst, PDSQ (point detonating super-quick), PD delayed-action or deactivate; it also contains a self-destruct element.  The projectile fuze measures the distance by counting the number of rotations: its spin rate is 21,000-28,000 rpm. The XM25 uses the same technology, with a shorter, lower-velocity cartridge limiting the range to around 700m rather than 2,000m.

The XM307 was originally intended to replace most of the .50 M2HB and 40mm Mk 19 AGLs, while the nearest comparators to the XM25 are the much bulkier six-shot revolvers chambered for the low-velocity 40mm grenade round, such as the  Milkor MGL, adopted by the USMC as the M32.  Adoption of the XM25 might therefore be expected to lead to a reduction in the use of the 40mm LV (low velocity) weapons, if not their eventual disappearance.

The manufacturers of 40mm GLs and ammunition are not taking this lying down, however, and have come up with a range of new developments to keep their products attractive.

Ammunition for Shoulder-Fired Grenade Launchers
The 40x46SR low velocity (LV) grenade round has now been around for almost half a century, originally chambered in stand-alone single-shot guns like the M79, but subsequently in underbarrel grenade launchers (UGL) such as the M203, and more recently the six-barrel revolvers mentioned above.  The muzzle velocity is only 250 fps, limiting the maximum range to about 400m.

The original round fired was the M406 HE/fragmentation type, and High Explosive Dual Purpose (HEDP) rounds have also been available for some time, enabling these launchers to be used to tackle light armour.  Some recent developments have considerably extended the versatility of this round.  From Arcus of Bulgaria comes the AR476 “Anti-Diver” grenade which has a time fuze which is set on impact with the water, detonating the HE at a stated depth of between 5 and 12 metres and with a claimed lethal radius of 12m.  They have also introduced the AR466 “Bouncing” ABHE grenade which on impact is kicked back up into the air by a small nose charge before detonating, to increase the lethal radius – not a new idea, but a very much cheaper way of providing some of the effectiveness of the sophisticated HEAB systems.  A similar RLV-FJ “Jump” round is offered by Arsenal, also of Bulgaria – a country which appears to be innovating with enthusiasm in this field.

More effective conventional ammunition has also been developed, with the latest trend being Medium Velocity (MV) rounds, with the muzzle velocity increased to between 350 and 410 fps, thereby doubling the effective range.  Recoil is claimed to be similar to that of a 12 gauge shotgun, and well below that of a rifle grenade, and they are designed to be used in many existing LV systems.  At a range of 150m the mid-range trajectory will be halved to about 3m and flight time is reduced.  The first in the field was Martin Electronics’ “Mercury”, which is significantly longer than standard 40mm HE rounds to make room for a larger HE charge, doubling the destructive power as well as the range of the conventional M433 HE grenade.  Nammo Raufoss, Heckler & Koch and now Denel of South Africa are also developing MV ammunition, while Arcus have developed “extended range” versions of their HE and ABHE products, capable of about 600m.

IMI and STK are even developing High Explosive Air Burst LV rounds to deliver the same effects as the XM25, although these do of course need to be used in conjunction with special sights with a laser rangefinder and fire control computer, and also a launcher modified to include an electronic fuze setter.  IMI have developed the compact and lightweight Orion sight which offers these facilities and can be fitted to any rifle in conjunction with a modified UGL.

Martin Electronics 40mm LV “DRACO” thermobaric grenade.

Martin Electronics have also introduced a thermobaric round, the DRACO; a type of explosive which is proving particularly popular in some larger weapons in use in the Middle East because of the effectiveness of its high blast overpressure in enclosed spaces such as buildings and caves.  The round is very expensive, however, so attention is now being focused on the much cheaper Hellhound.

The peacekeeping roles which armies frequently have to adopt have generated growing interest in Less-Lethal ammunition for riot control and similar policing activities.  Many manufacturers now offer a very varied range of irritant chemical, impact, combined and paint marker ammunition too extensive to describe here.  Although such munitions have traditionally been used in specialised 37/38mm riot guns, they are increasingly available for the 40mm LV grenade launchers – and, in a few instances, for the 40mm HV AGL as well.

Other types of rounds which are not directly lethal include various smoke and flare types.  There are also some novel developments, most notably the observation rounds containing parachute-borne video cameras that send pictures directly back to the operator, providing an instant view of what lies over the hill or around the corner.  Both STK (with the SPARCS) and Martin Electronics (with the HUNTIR) have developed such rounds for 40mm LV grenade launchers, while the Rafael Firefly, still in development, is equipped with folding “wings” rather than a parachute.

Many of the new rounds are longer than standard, at up to 5.5 inches.  In contrast, ammunition for the semiautomatic XM25 is limited in size (the maximum length is only about 3.5 inches), and cannot hope to emulate the variety of types now available for the 40mm LV GLs, which will be with us for the foreseeable future.

40mm AGLs
The success of the original 40mm LV grenade rounds rapidly led to the development of fast-firing weapons chambered for them, but almost as quickly the need for greater range was realised, so the 40x53SR high velocity (HV) cartridge was developed.  This had the muzzle velocity increased to around 800 fps which, in conjunction with a heavier grenade (about 240g compared with 180g), increased the effective range out to 2,000m.  The first automatic grenade launchers (AGLs – also known as grenade machine guns or GMGs) chambered for this round were externally powered and designed for installation in helicopters: the M75 and M129 both seeing service in Vietnam.  Far more important, however, was a self-powered design, the Mk 19.  This was developed in the late 1960s as a USN project but was subsequently adopted by other services, as well as achieving substantial export sales.

Since then, and particularly since the 1990s, a number of rival AGLs have emerged from several different countries: the Spanish Santa Barbara (now General Dynamics Santa Barbara Sistemas) LAG 40 SB, the Singapore Technologies Kinetics (STK) 40AGL and Light Weight AGL, the Heckler & Koch HK40 GMG (recently bought by the British Army), South Africa’s Denel Y3 AGL, and other weapons from Romania, Poland, Turkey and Pakistan.  Of most significance to the USA is the CG40, a joint project between three companies, commencing in 1995: Nammo (ammunition), General Dynamics Canada (Fire Control) and Saco Defense (now a part of GD) who developed the gun and dealt with system integration.  Some 400 are in service with US special forces, ordered between 2001-5, under the designation Mk 47 Striker.

The HV ammunition used in these guns has not shown the variety found in the LV rounds, partly because of the narrower range of uses of the AGLs and partly because the need to function in an automatic mechanism restricts the characteristics – and particularly the overall length – of the cartridge.  However, a great deal of attention is now being paid to the development of the same kind of airburst technology as that being tested in the XM307.

Nammo 40mm HV PPHE rounds.

The way is being led by Nammo Raufoss, who have developed HEAB ammunition as a part of the CG40 project, under the designation PPHE (Programmable Pre-fragmented HE).  The gun was designed for this from the start, the necessary systems being integrated into the weapon.  These include an image-intensifying video sight linked to a laser rangefinder and incorporating a ballistic computer to indicate the exact aiming point, and an electronic fuze setter by the gun breech.  When used with the appropriate ammunition fitted with the Mk 438 programmable time fuze, the system sets the appropriate time delay on the fuze while it is in the chamber (the gun fires from a closed bolt) so that the grenade bursts directly over the target.  The gun can also use conventional point-detonating 40x53SR ammunition, with which the advanced sights are still useful in providing a high level of accuracy.  The Mk 285 HEAB projectile produces fragments which are mainly distributed sideways and backwards to catch troops behind cover, rather than forwards as with a conventional grenade.  An initial order for 39,000 of this round has been placed for use in the Mk 47 Striker, with deliveries expected to be completed by early 2008.

Nammo are also working on a variation of this system for guns, such as the HK40 GMG, which fire from an open bolt.  The chosen system is radio frequency programming, the fuze being set about 4 to 5 metres after the grenade has left the muzzle.  Since all of the system requirements are contained within a single sight/fire-control/programming unit, this can be fitted to any gun able to mount the unit.

There is yet a third HEAB system, from STK of Singapore; the ABMS (Air Bursting Munition System), which can also be fitted to existing 40mm AGLs.  This was developed in conjunction with Oerlikon-Contraves Pyrotec AG of Switzerland, who adapted the technology developed for their 35mm AHEAD cannon ammunition.  As with AHEAD, the fuze-setting system is attached to the muzzle and sets the fuze as the grenade leaves the barrel.  Like the Nammo systems, special grenades are used with an all-round fragmentation pattern, so they throw fragments behind them as well as in front and to the sides; the Oerlikon/STK type contains 330+ tungsten balls, each weighing 0.25g and intended to penetrate at least some grades of body armour.  The effective range of the system is 40 to 1,600m.

Sectioned 25x59B HEAB for XM307 ACSW.

In the rush to airburst systems, the value of the conventional (and much cheaper) ammunition has not been forgotten.  Nammo have developed a ‘product improved’ M430 HEDP round at the request of the USMC, who have asked for a mechanical self-destruct fuze, a modified (NICO type) propulsion system, insensitive munition (IM) properties using a PBXN-11 main charge, additional incendiary after-armour effect, penetration improved from three to four inches of RHA, and a reduced safety zone to prevent the base of projectile from being blown back towards the gunner (the current limitations being 310m in peacetime, 75m in wartime).  Internal Nammo qualification of this round is expected in spring 2008.

While the 25mm XM307 offers certain advantages, notably gun and ammunition weight plus a much flatter trajectory and shorter flight time, the 40mm AGLs clearly have a lot of life in them yet.  Their ability to fire inexpensive standard ammunition as well as sophisticated HEAB rounds means that they are likely to remain popular long after the XM307 enters service.