We at SADJ wanted to cover the history of U.S. grenade machine guns, and with a recent visit to US Ordnance, the prime manufacturer of the MK19 Mod 3, it seemed like a perfect time. Later in this article, we’ll cover the modern MK19 system and improvements in depth. But first, a look at where we’ve come from...

Throwing grenades is nothing new. Reports of tossing explosives at enemies go back to the dark ages and certainly many armies had “grenadiers” in the 1700s and 1800s; light the fuse, toss the grenade. It wasn’t until mechanical fuses and primer firing were evolved that the idea of launching grenades automatically occurred. There are many early patents for weapons designed to launch explosive devices, but until the 1950s, the U.S. didn’t take the idea too seriously. With the advent of the 40x46mm grenade and its legendary M79 launcher, wheels started turning in the minds of designers and soldiers alike. Evolution of the single shot launchers has been covered in-depth by SADJ in the past; it is the idea of the U.S. designed, belt-fed, quickly repeating launchers that is our subject.

A proper timeline would be in two lines; the 40x46mm low velocity rounds, and the 40x53mm high velocity rounds. LV rounds have a range of 350-400 meters and can be shoulder fired or fired in a vehicle-mounted full-auto launcher, the HV rounds can go out to 2200 meters and are not for shoulder fired launchers.

Approximate Milestones for 40×46 Low Velocity Development:

1950s: Development of the 40x46mm low velocity grenade, and M79 launcher.
1965: Development and deployment of the MK18 Mod 0 crank fired launcher.
1968-71: Development and deployment of the MK20 Mod 0 automatic launcher.
1968: Development and deployment of various XM174E2 launchers.
1968: Development and deployment of the dual caliber M129 helicopter gun.

Approximate Milestones for 40×53 High Velocity Development:

1964: Final evolution of the 40x53mm high velocity grenade.
1966: MK19 Mod 0 design at Naval Ordnance Station, Louisville.
1969-74: Development of the Hughes XM175 series of launchers.
1968: Deployment of the first MK19 Mod 0 to Vietnam.
1971: Deployment of the first MK19 Mod 1 to Vietnam.
1974: Development of the MK19 Mod 2, not fielded.
1970s (Approximate): 600 MK19 Mod 2 Aluminum receiver guns- Israel.
1984-1989: Final development and manufacture of the MK19 Mod 3 by Saco Defense, then 1990s General Dynamics, and currently US Ordnance.

“The Honeywell Gun,” variously called the XM172, or the MK18 Mod 0, this was a crank fired belt fed, with 40x46mm ammunition; the same ammunition used in the M203/M79/M320 system. The ammunition is pre-loaded into a tape that holds the case in line with the barrel. Two rounds were fired per full revolution of the belt, allowing for slow, ranging fire, or firing up to about 250 rounds per minute. Belts were 24- or 48-round lengths. This was into action in about 1965 and survived in various places for U.S. forces (Navy) in Vietnam, primarily on “PBRs” (patrol boat, river) although some use on Chinook helicopters working over landing zone perimeters was seen.

MK18 Mod 0 with the cover open, showing the lower rotor with a round in position, and the upper rotor inside the cover. The two rotors are keyed together so that when the top cover is down, each rotor makes half of the chamber. Since it is Hi-Low pressure, low velocity, the round can be fired like this, and much like a revolver, the projectile must enter a separate barrel. The rounds were initially held in a metallic tape, since they didn’t need to be extracted, the tape simply came through with empty cartridge cases in it. This was later changed to a reloadable Mylar backed fabric which, for many, doubled as a grenadier’s belt for the M79 shooters.

Around 1966, the Navy wanted a better system than hand-cranking. Colonel George M. Chinn, author of the famous five-volume series of books “The Machine Gun” was involved. His team at Naval Ordnance Station in Louisville, Kentucky was simultaneously involved in designing an automatic grenade launcher to replace the crank-fired MK18 and, by 1967, the team had the boxlike MK20 Mod 0 in 40x46mm, and was preparing for the new MK19 system in 40x53mm.

The MK20 is an unusual design, the cocking handle is pushed forward, and the barrel moves forward and stays “cocked.” On pushing the trigger, the barrel springs to the rear, over the grenade, pushing it onto the firing pin and the barrel moves forward with the projectile moving forward in its bore. The cycle repeats as long as the trigger is depressed. Production was ended in 1971, when Chinn’s group was advancing the MK19 system.

The MK19 Mod 0 was fielded, at first, in 1968 in small numbers in Vietnam, and was an unreliable system. It utilized the newly designed 40x53mm round, and fired from an “open bolt” but using ‘advance primer ignition’. This means the firing pin struck the primer before the cartridge was fully seated and in battery. The Mod 1 debuted as in this example in 1971 and, by 1974, it was evident that there were reliability issues and a “Mod 2” was designed but not implemented. These were all done by Colonel Chinn’s team at the Naval Ordnance Station in Louisville, Kentucky.

There was, in fact, a production of the Mod 2. The MK19 Mod 2 Israeli contract gun in 40x53mm with an aluminum receiver. Approximately 600 were made. There’s no clear historical evidence pointing to the location of actual manufacture; at Naval Ordnance, or as a technical data package exported to Israel, perhaps with parts for assembly abroad.

In any event, these functioned but were not advanced into larger production and the MK19 Mod 3 replaced them in service. The Israeli Mod 2s were sold on the surplus market, and the parts were initially offered as “MK19 Mod 3” replacement parts in the mid-2000s, but of course none of the parts interchanged with the Mod 3 guns. Some steel receivers were made and project guns tested in the U.S. by a variety of smaller manufacturers, but there was a clear size and parts difference with the issue MK19 Mod 3. Today, it appears these parts are offered as “MK19 Mod 2.5” complete guns in a modern production, new receiver program. Not to discourage potential end users, but these are not compatible with the MK19 Mod 3 system, which is physically larger and does not interchange parts. It would be inadvisable to mix the systems and support, so if the Mod 2.5 is chosen, it should be supported on its own and verification of spare parts supply should be done.

M129: This is a unique electrically operated system that had a cam path in the receiver housing, but instead of the bolt traveling in that path like a Gatling or an M134, the barrel reciprocated. The barrel would start in the forward position, and when fired would cam back over the round, fire it, then move forward for extraction. These were mounted in chin pods on the front of many Huey gunships in Vietnam as well as other rotary winged aircraft. It replaced the very similar M75 system which had accuracy issues, among other problems. The M129 could fire either 40x46mm or 40x53mm grenades, depending on how the feed was set up.

The XM174E2 was a drum fed 40x46mm automatic gun on tripod that was made in very small quantity in the late 1960s by Aerojet Ordnance & Manufacturing Company. These made a shadowy appearance in Vietnam: Colonel David Lutz, USMC ret’d, told this author once of how he’d found two of these XM174E2s with drum feeds at a base armory and took them to his area of operations in the A Shau valley. He and his men were quite impressed with the accuracy and firepower in fighting the Vietcong and NVA, and wanted more of them. As Colonel Lutz (Lt. Lutz at the time) stated it “Then, adult supervision showed up, demanded to know where we had gotten these, and took them away in that time-honored military tradition of if it works well, you can’t have it.”

In the late 1960s and early 1970s, there were two versions of the M175 40x53mm grenade machine gun; first was the XM175AL (above, left) which had a milled, rounded receiver, and the second version XM175ST (above, right) had a boxlike sheet metal receiver. Hughes Gun Systems in Culver City, California was the design group and manufacturer. Both were open bolt firing, link-belt fed, could be converted to be right- or left-feed, and did not require external power like the M129. The M175 was designed initially for ground vehicle use, and then the vision changed for it to become a manually operated helicopter door gun.

More on the MK19 in the Modern Day….

In the 1980s, FNMI in South Carolina was awarded the contracts for the M16A2, the M249 SAW, the M240G, and the MK19 Mod 3, all at the same time. Chief Engineer George Kontis described the situation, “We knew we could not properly perform all four of the contracts simultaneously, and the contracting officer did as well, and offered our choice of three—leave one behind. After a full review, I determined that the MK19 Mod 3 TDP and learning curve would be the hardest, so FNMI withdrew from the MK19.”

Saco Defense was awarded the contract for MK19 Mod 3, and it took almost six years to develop the TDP and production process on the especially difficult receiver and bolt production. We visited the Saco facility numerous times during this period and tested the weapon in many of the phases of production along with the M6E4 program run by Marc Desrochers. Kevin Sullivan of today’s Nostromo company was project manager in the mid to later MK19 program success. Saco was bought out by General Dynamics, and the GD MK19 Mod 3 production was in full delivery for many years. Several other companies have tried to go into production, but the advantage goes to larger companies, and indeed the U.S. DoD wanted a secondary manufacturer capability during the Iraq and Afghanistan wars; ATK was awarded this, with FN Manufacturing as a subcontractor on the receivers and bolt bodies.

In the 1990s, I was involved in importation of special tripods and mounts from Vinghog of Norway for my USG customers. At that time, the accepted first burst hit probability at 1000 meters for the MK19 Mod 3 on M3 tripod with fixed cradle was approximately 53%. In our testing for U.S. government agencies, we ascertained that the HK GMG had a much higher first burst hit probability, and much of that advantage was in the tripod and soft mount as well as a good sighting system. (GMG testing for this author started in 1993 and continued through the Yuma Proving Ground tests in 1996-97. It’s a fine GMG but not the subject of this article).  

The customers wanted to retrofit their MK19s to gain similar accuracy. With the addition of the special Norwegian soft mount, the Adjustable Sight Mounting Bracket and some rudimentary head’s up sights with 40mm gradients, we brought the MK19 Mod 3 reliability to about 85% for first burst at 1000m. My point? The MK19 Mod 3 is an excellent grenade machine gun that needs mount stability and proper sighting. The advancements since that time have been by leaps and bounds, with the ability to land short bursts at long ranges increasing exponentially.

The MWO

There is a program that came out of the accuracy testing that was done. In June of 2002, a five-year plan was adopted for the MK19 Mod 3s in the U.S. Army system. MWO 9-1010-230-50-1 was implemented with an expected completion date of June 2007. However, that was only in the U.S. Army and later USMC/USN inventories; there are still tens of thousands of MK19 Mod 3 around the world that need this upgrade.

The purpose of this particular modification work order (MWO) is to convert the MK19 Mod 3 Grenade Machine Gun, to the MK19 Mod 3 with Adjustable Sight Mounting Bracket. Maintenance time is reduced and there is now a structural mounting point for fire control devices. The previous “sight mount” was a half-step, providing a not very secure rail base to the existing rear sight body. With this new purpose-designed mounting base, a variety of enhanced sighting devices can finally be used. The modification kit has the trapezoidal mounting base & screws, along with directions, and, for the armory, a fixture for drilling. This MWO was used as a vehicle to provide some upgrading of other parts, in particular the firing pin, firing pin sear, cam cocking, cocking lever and an adjustable secondary drive lever. 

US Ordnance has the contracts for the M60E4 (the Navy SEALs’ MK43), the US M2A1 .50 caliber, as well as M240 series and other M2 guns. After several years of research and prototyping, then going into production, US Ordnance perfected their MK19 Mod 3 manufacturing procedures. They had also inherited one of the original technical data packages (TDPs) that came from Colonel Chinn, and benefitted from employees who worked the original Saco and General Dynamics programs. In their arrangements with General Dynamics and the U.S. government, US Ordnance contracted to be the manufacturer of the MK19 Mod 3 grenade machine gun. They are the official U.S. government contractor for this system, as well as for foreign military sales (FMS) and sales to allied buyers. SADJ toured the manufacturing facility recently, and with the new U.S. government contract to supply all MK19 Mod 3 and repair parts, US Ordnance is preparing for a full mil-spec live-fire test, which we will participate in and bring the report to our readers. There is a complete upgrade program that should be available to most longtime users of the MK19 Mod 3 system. Rather, it is available, but many end users are not aware of it. I have participated in several over the years, but US Ordnance is the primary on this type of project. They can gauge your existing guns, recommend the upgrades, perform them in the factory or set up on site programs. This will not work on the MK19 Mod 1, Mod 2, or the “Mod 2.5” as can be seen in the history of the development, they are different guns from the most prolific and reliable Mod 3. Contrary to some advertising and “internet wizards,” the parts of those other models do not interchange with the MK19 Mod 3 40mm Grenade Machine Gun, and it is our sincere hope that this guide will help identify what systems are in place, and how to upgrade, repair, and maintain them.

Meanwhile, in the USSR…

While the U.S. was developing the 40x46mm and 40x53mm grenade machine guns, the Soviets were designing, as well. In 1965 the AGS concept was born and by 1971, production had begun. The AGS-17 30x29mm Grenade Machine Gun is a lightweight, tripod or vehicle mounted open bolt grenade launcher. It’s quite effective, and the smaller diameter, longer grenades have an almost spear-like travel to target. However, at 1700 meters range the time to target is very long, due to the high trajectory arc. Typically, the AGS is drum fed with 29 linked rounds per drum. SADJ has covered these extensively in the past and the analysis can be found at our websites.

Grenade Launcher Ammunition

40x46mm HE Fragmentation Hi-Low pressure, low velocity cutaway round for the M203/M79/M320 type launchers. The multiple fuses are in the front, the fragmentation ball is in the center (without energetics), and the base shows how the Hi-Low pressure system works. The primer is fired, igniting propellant in the central chamber which expands. When it reaches X pressure, it blows out through the vent holes into the sides into a much larger expansion chamber, creating a lower pressure that “pushes” the grenade into the barrel and downrange. Range is 350-400 meters.

At center is the 40x53mm Hi-Low pressure, high velocity cutaway round for the MK19/GMG and other Grenade Machine Gun systems, it is evident from the thick walls of the spherical chamber that there is much more pressure involved here. The cartridge case is 9mm longer than the 40×46 low velocity (M203) round, and the 40x53mm round cannot be chambered in the shoulder fired launchers. Range is out to 2200 meters, depending on firing platform.

Right is the VOG-25 40mm grenade, a “caseless” round that is front loaded into the barrel of the GP-25/30/34 underbarrel launchers. When the primer is struck, it ignites the propellant in the chamber at the very bottom, the expanding propellant gasses vent out into the base of the launcher forming the secondary low-pressure chamber and drive the grenade down the bore and downrange. There is no cartridge case left, it has all left the launcher downrange. Range is 350-400 meters.

During World War II, the basic weapons of the U.S. infantryman were the rifle, light machine gun and fragmentation grenades. Hand and rifle grenades were used for short-range area targets. Hand-thrown grenades have a realistic range of 30 to 50 yards. The maximum range of rifle-launched grenades was approximately 100 yards; both were ill-suited for engaging targets with accurate indirect fire. Light mortars were used for ranges from 300 to 900 yards. The same weapons and limitations were fielded during the Korean Conflict by U.S. infantryman.

The Rifle Grenade Launcher

During the late 1950s, the M7A3 grenade launcher adapter was being issued for use on the M1 rifle. After the M14 rifle replaced the M1, the M76 grenade launcher was adopted. For accuracy, the M15 tilting-bar sight, designed to be attached to the M14 rifle’s stock, was issued for use with the M76 launcher. Special “grenade launching cartridges” were used. Rifle grenades could also be launched from the M16 rifle, but no special adapter was needed; grenades could be slipped over the NATO standard 22mm diameter flash suppressor. Disadvantages of launching grenades from rifle barrels included: short range, inaccuracy and heavy recoil that would sometimes break buttstocks.

Clearly, a new weapon was needed, one that could provide accurate direct and indirect fire to fill the gap between the rifle, hand grenades and the light mortar. During the 1950s the United States Ordnance Department began development of a weapon that could fire high explosive munitions, multiple projectile anti-personnel rounds and smoke and illumination rounds.

40mm Ammunition

During the early 1950s the Ballistic Research Laboratories at the Aberdeen Proving Ground developed a 40mm high-explosive, fragmentation projectile. The goal was a range of 400 meters at the relatively low velocity of 250 feet per second, with a recoil force no more than that of a 12-gauge shotgun. The new projectile used a high-low pressure system, which was developed by the German firm of Rheinmetall-Borsig during World War II for their 8cm 8H63 anti-tank gun. The advantage of the high-low system was that a lightweight barrel could be used, reducing the overall weight of the weapon.

The M79 Grenade Launcher

The concept of a lightweight weapon capable of projecting a grenade further than could be thrown by hand and could exceed the range of rifle-launched grenades was coordinated by the Small Arms Development Branch, headed by Colonel Studler. Jack Bird, a deputy to Colonel Studler, took an interest in the project; he built a crude launcher and brought it to the Pentagon to demonstrate. The device was comprised of a short length of tubing with the same inside diameter as a golf ball. To operate the “launcher,” a golf ball would be placed inside the tube and compressed against a spring. The golf ball was secured in place with a nail. Upon removing the nail, the golf ball would be launched. Bird, an avid golfer, suggested the name “Project Niblick” after the number nine iron, a high lofting golf club.

During 1953, the Project Niblick grenade launcher was under development at the Springfield Armory under the guidance of Cy Moore, with Dave Katz, a design engineer. The Picatinny Arsenal provided 40mm practice grenades for firing in the prototype launchers. There were three types of launchers being developed: a crude shoulder fired test fixture, a pistol and a three-shot semiautomatic launcher. The fixture was primarily a means of testing the ammunition to get an idea of the range and accuracy. The weight of the projectile was approximately 5.3 ounces. When launched with a quadrant elevation of 35 degrees, it had a range of 400 meters. Development commenced at the Springfield Armory. Proposed designs were identified by a letter “S” representing the Springfield Armory. Many of the designs never made it any further than the drawing board.

The Infantry Board at Fort Benning stated that they preferred a three-shot grenade launcher. A barrel length of 14 inches evolved as the length to make it unlikely that the gunner could get his fingers in front of the muzzle while firing. The three-shot launcher achieved semiautomatic operation through the use of a clip made up of three side-by-side chambers, each long enough to house a cartridge about 3.5 inches long. The clips would move to the left after firing by a constant force of a negator spring. As each round was fired, a latch detected the launching of the projectile and allowed the clip to move over until stopped by the next projectile, lining up that cartridge with the barrel. Although the basic concept was simple, the mechanism proved to be complex and unreliable. Continued misalignment between the projectile on the bore created gas leakage and a loss of accuracy. Special purpose rounds, such as CS gas or signal flares with a longer overall length, could not be used. The simplest design, designated as the “S-5,” was a single-shot, break-open type weapon. The S-5 evolved into the XM79 in 1959 after the three-shot S-6, T148E1 project was canceled.

After the idea of a multi-shot, semiautomatic launcher was scrapped, it was replaced by a simple, single-shot weapon, patterned after a break-open type shotgun. One launcher was ordered from Dave Mathewson, who operated a local fabrication shop, often used by the Springfield Armory. To keep the weight at a minimum, the weapon featured a hard-coated aluminum barrel. The odd shape of the stock was designed so that the bottom edge would be aligned with the line of recoil; the top or comb is contoured to keep the grenadier’s head upright owing to the line of sight relief when firing at low angles. To reduce the effects of the recoil on the shooter, a rubber recoil pad was fitted to the butt of the stock. The Infantry Board suggested a folding leaf sight mounted on the barrel with a bead front sight just above the muzzle. The XM79 launcher was sent to the Infantry Board in 1956 and was recommended for type classification in 1957.

To load the weapon, the operator simply moves the barrel-locking latch counter-clockwise to open the breech. Moving the release latch automatically puts the weapon into a safe position; opening the breech cocks the weapon. After closing the barrel, the safety must be pushed forward to fire. The weapon is easily field stripped by removing the front sling swivel screw and removing the forend. The barrel can then be disengaged from the fulcrum pin and separated from the receiver group.

The weight of the loaded launcher is 6.45 pounds; overall length is 28.78 inches. The stock and forearm are made of walnut. The rest of the weapon, except for the aluminum barrel, uses steel parts phosphated for corrosion protection. The original contract price for the M79 was $318.00 each. The M79 was issued with a small arms accessory case, which included a bore brush, plastic oil tube, combination tool and cleaning brush. Early carrying cases for the kit were made of canvas, later changed to vinyl.

During testing by the Infantry Board in June 1960, it was recommended that a new rear sight for the M79 launcher be designed and fabricated. The new sight was completed in October 1960. The early ladder-type sight was replaced with an adjustable, single crosspiece-type sight with a correction for azimuth. All launchers produced up to June 1960 had to be retrofitted. Confirmatory tests in December 1960 revealed requirements for additional windage adjustment on the rear sight. The additional sight modification was incorporated in the first production run. R&D continued in order to improve the reliability and function of the weapon. The launcher was considered acceptable by the Continental Army Command (CONARC) and was subsequently type-classified as the Launcher, Grenade, 40mm, M79 on December 15, 1960. By the first quarter of 1961, the new adjustable rear leaf sight was in full production, and several mandatory changes were implemented on the barrel locking lug, trigger spring and front sight.

The heat and humidity being experienced in Vietnam were causing problems with the warping and swelling of the wooden stocks of the M79. As a result, work began on designing a plastic buttstock and foregrip for the weapon. By 1964, a suitable plastic buttstock was available; General Tire was the primary contractor. There were no plastic foregrips adopted.

Although the M79 grenade launcher was designed and developed at the Springfield Armory, the majority were manufactured by civilian companies. Contracts awarded to private industry included: Action Manufacturing Company, Philadelphia, Pennsylvania, Contract DA-11-1199-ORD-736 and Exotic Metal Products, Pasadena, California, Contract DA-11-199-ORD-730. Other contracts were subsequently awarded to the Kanarr Corporation of Kingston, Pennsylvania, and Thompson Ramo Wooldridge (TRW) of Lyndhurst, Ohio. The decision to have private companies manufacture the M79, resulted in a lot of resentment with the civilian employees of the Springfield Armory. Series production ran from 1961 to 1971 with an estimated 350,000 M79 launchers produced.

Despite being replaced by modern grenade launchers, like the M320A1 and the M32A1, the M79 is still being fielded by the U.S. military.

The China Lake Grenade Launcher

Developed for the U.S. Navy SEAL teams was a limited production, pump-action 40mm grenade launcher, fed from an under-barrel tubular three-round magazine. The launcher was fitted with M79 front and rear sights and a shotgun-style stock. There was no official designation other than “The China Lake Grenade Launcher.” The weapon was developed at the Naval Weapons Center, China Lake, California, during 1967-1968.

The XM148 Grenade Launcher

While the adoption of the M79 grenade launcher solved one problem, it created another; it reduced the number of riflemen in a squad, the man carrying the single-shot M79 was usually armed with only a pistol for self-defense. To address the problem, the concept of the rifle-mounted launcher was studied. The 40mm XM148 launcher, first issued in 1967, was designed for mounting under the barrel of an M16 rifle. The weapon was developed by Colt Firearms to allow each rifleman in an infantry squad the ability to launch 40mm grenades, rather than one man equipped with an M79. During field testing in Vietnam, a number of problems were encountered. The XM148 launcher was not considered reliable or safe enough for type classification, and the launchers were pulled from service; most were destroyed.

The M203 Grenade Launcher

After the XM148 grenade launcher was scrapped, the concept of a rifle-mounted launcher was not. The Army initiated a competitive program for a new 40mm rifle-mounted grenade launcher. Designs were submitted by Aircraft Armaments Inc., Ford Aerospace and Communications Corporation and Aerojet Ordnance and Manufacturing Company. During August 1968, the Aircraft Armaments (AAI) design was type-classified as the XM203 grenade launcher. A small lot was manufactured and shipped to Vietnam for field testing. AAI’s XM203 40mm grenade launcher was found to be simple, safe and reliable. After successful testing and evaluation, the Aircraft Armaments design was type-classified as the Launcher, Grenade 40mm, M203 in 1969. Ironically, Aircraft Armaments, who developed the weapon, did not have the capacity to produce the number required by the Army, and a contract to manufacture the M203 was awarded to Colt Firearms. The U.S. M4 Carbine version of the M16 was adopted in 1994. The M203 launcher would not fit on the shorter M4. The M203 GL was modified into the M203A1, which is functionally the same as the M203 but is designed to fit on the M4 and M4A1 carbines. The quick-release M203A2 was designed for M4 carbines with a rail system and with M16A4 rifles that have the M5 adapter rail. Currently, there are at least seven U.S. companies manufacturing the M203 grenade launchers and its variants.

The M320 Grenade Launcher

During 2004, the U.S. Army issued a requirement for a new technically advanced grenade launcher with improved accuracy, ergonomics, safety and function as a stand-alone weapon. Development of the XM320 single-shot launcher, based on the HK AG36, began at the Picatinny Arsenal. The 40mm M320, which can also be attached under the barrel of a host weapon, was adopted in 2016 to replace the M203 under-barrel launcher.

The M32A1 Multi-Shot Grenade Launcher

While fighting in Iraq, the U.S. Marines requested a grenade launcher with a rapid rate of fire. An off-the-shelf, multi-shot revolver type, semiautomatic launcher was submitted by Milkor USA based in Arizona. The weapon was tested in 2006 and was eventually adopted by the U.S. Marine Corps as the M32A1 Multi-shot Grenade Launcher, and by the USSOCOM as the Mk 14 Mod 0.

As basic review, recall that the most recent variants of 40mm grenade systems are typically deemed “third generation” systems, following the design of the M79 40mm grenade launcher, the original first generation 40mm grenade launcher. Later second generation launchers are represented by the Colt M203, and the Heckler and Koch M69 launchers as systems that require mounting to the host weapon. The newest 40mm grenade launchers represent an entirely new system of weapons, representing the third generation of the 40mm grenade launcher. In general terms, third generation 40mm grenade launcher systems are defined as a multifunctional 40mm grenade launcher. That is, they are capable of functioning as a standalone unit or as part of an integrated rifle system. Third generation systems frequently feature the increased use of aluminum, composites, and polymers within the manufacturing process, and generally rely upon a side opening breech, rather than the M203’s slide forward breech mechanism. By opening to the side, the third generation systems are better capable of accepting 40mm rounds that are longer in length than the original M583 parachute flare round. This is a significant and important feature as increasing numbers of less lethal and medium velocity 40mm rounds enter the market. Finally, third generation systems all feature universal mounting solutions reliant upon Mil-Std 1913 Picatinny rails as a means of mounting the launcher to the host weapon. By presenting a universal mounting solution, third generation 40mm systems offer a unilateral cross-platform 40mm solution – that is, a single 40mm weapon system may be mounted on a host of primary weapons, without special tools in a quick and efficient manner. Mounting a third generation system to the host weapon typically requires the minimal use of common hand tools rather than relying upon specialized mounting hardware typically required to mount second generation 40mm systems to the host weapon. It should be no surprise that the Fabrique Nationale FN40GL system fits the definition of a third generation 40mm system nearly exactly.

The System

The FN40GL Enhanced Grenade Launcher is intended for integration with the Fabrique Nationale SCAR 16 and SCAR 17 rifles. Capable of firing all types of NATO standard 40x46mm low-velocity grenades, the FN40GL may be mounted under either rifle or may be configured as a stand-alone launcher.

When assembled on a Mk16/Mk17 host rifle, mounting is easily accomplished with a trigger adapter and dual locking clamp levers. The FN40GL easily mounts to the Picatinny rails at the 6 o’clock position on the host rifle. No special tools to mount or dismount the launcher from the host rifle are required as one merely flips the two mounting levers upward. The mounting system is as easily manipulated as any common Picatinny rail attachment. When mounted to the host rifle, the FN40GL is firmly mounted without any flex or movement, yet is easily removed quickly and without the use of tools.

Completely ambidextrous, the FN40GL utilizes a polymer receiver mated to an aluminum barrel for durability and light weight. Unlike other third generation 40mm systems, the 9.6-inch barrel swivels to the right or left for ease of loading and unloading from any firing position. This feature differentiates the FN40GL from other 40mm systems. While other systems allow the barrel to pivot to either the left or right, other 40mm systems force the user to choose one direction or the other. The FN40GL is currently the only 40mm system that allows the barrel to pivot in either direction at any time. While this may not seem significant, the ability to load the weapon from either the left or right allows left handed shooters to utilize a standard system without modification. More importantly, the design allows the shooter to load the weapon in any position – left or right – an important feature when loading from one side may prove difficult or impossible in the heat of battle.

The FN40GL may also be mounted to an alloy stand-alone stock assembly to allow individual use of the system. While the launcher is outfitted with Mil-Std 1913 Picatinny rails at the 12 o’clock position, the stand-alone stock assembly provides rails at the 3 o’clock, 6 o’clock, and 9 o’clock positions to allow the mounting of lights, lasers and other targeting devices. While this may not seem significant, recall than 40mm systems are being used in increasing numbers in a less lethal role. The ability to mount a forward grip, red dot sight, and laser aiming modules on the system may prove valuable on the battlefield, while the ability to mount ultra-bright LED lights and eye safe laser dazzlers may be more appropriate for use in situations involving civil disobedience.

Fabrique Nationale offers the FN40GL with a traditional folding leaf sight as standard sights. The application of optional after-market grenade launching sights or laser aiming modules is easily mounted to the system via the built in Mil-Std 1913 Picatinny rails.

At the Range

The FN40GL is a manually operated, single shot grenade launcher. Loading is easily accomplished by loading a 40mm grenade within the chamber of the weapon and closing the breech. The breech is a multiple lug rotating design. Unloading is easily accomplished by opening the breech via a lever on the left side of the weapon and removing the live round. The lever to open the breach is intuitive for right handed shooters, and is located in approximately the same location as the legacy M203 system. As the system opens to the left and right, an ambidextrous opening lever would be innovative, yet mechanically difficult to achieve with the current design.

The trigger of the system is unusually large and placed low on the weapon system. While the system was fired using the stand alone stock, it appears that the placement of the FN40GL trigger may allow the operator to keep the index (trigger) finger on the trigger of the host weapon, while using the shooter’s middle finger to fire the FN40GL. Regardless of finger placement, the FN40GL features a double action only trigger system that proved long and heavy. While firing the system was under ideal conditions, one must recall that most users will be firing the system under duress, whether a civil disturbance using less-lethal rounds, or on the battle field, firing high explosive rounds. The stress likely faced when firing the system necessarily requires a double action trigger as a means of preventing fratricide and unintended discharges of the weapon. When firing high explosive, one can never be too careful.

Accuracy of the system using the FN designed leaf sight was reasonable and targets at 250 meters were easily engaged within the kill radius of an M433 HE round. Presumably, accuracy would be better when used in conjunction with electronic or laser sighting systems. Muzzle velocity was approximately 250 feet per second.

Conclusion

The FN40GL is a highly capable third generation 40mm system. While the double action only trigger pull is not ideal, the long and heavy trigger pull is likely to prevent accidental discharges in high stress situations. It can be differentiated from others in the market in that the FN40GL is currently the only 40mm system that allows the barrel to pivot in either direction during the loading sequence. The system appears to be currently adaptable only to the FN SCAR 16 and SCAR 17, giving limited use on rifles outside of the FN family. Although tested with a standard leaf sight, accuracy of the system would presumably benefit with the addition of an aftermarket laser range finder, laser designator, or sighting system. Wide use of Mil-Std 1913 Picatinny rails allow the mounting of nearly any aftermarket sighting system. Additional information may be found online at www.fnhusa.com.

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 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.

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.

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.

(Anthony G Williams is Co-editor of Jane’s Ammunition Handbook, and maintains a website at http://www.quarry.nildram.co.uk)

Working with outside companies such as Honeywell Incorporated, Picatinny came up with a fuze system for the new grenade that was considered a marvel of miniaturization at the time. Even with the small size of the fuze, it was as large as the fragmentation body itself and made up over 50% of the complete projectile. Further studies of the new projectile centered on determining which would be the best way to launch and stabilize it in flight.

Colonel Rene R. Stutler, Chief of Small Arms Research and Development for US Army Ordnance, at his office in the Pentagon had decided that a shoulder fired launcher dedicated to launching the new grenade would be the way the project would go forward. A deputy to Colonel Stutler, Jack Bird, became interested in the grenade launcher project and investigated the idea on his own time.

Taking a piece of pipe that would accept a golf ball, Bird capped off one end and drilled several small holes through the tube’s side. With a spring placed in the tube and a golf ball dropped down over the spring, a stick was used to push the ball down against the pressure of the spring. A nail slipped through one of the holes in the side of the tube held the ball in place on the compressed spring.

Demonstrations of Bird’s “launcher” took place in the central courtyard of the Pentagon. The high arcing trajectory of the golf ball when the cross nail was pulled out demonstrated remarkable accuracy for such a crude device. The high lobbing arc of the ball reminded a number of the onlookers of a nine-iron stroke on a golf course. Jack Bird suggested the program for the new weapon be named after the popular term for a nine-iron at the time, a Niblick. Stutler agreed and Project Niblick was so named.

Once the basic projectile had been established, both a launcher and a means of propelling the grenade were needed. Springfield Armory received funds in June 1952 for its Research and Development Division to conduct a study of various devices to launch the new grenade design. A number of designs were established, built, and tested at Springfield Armory using the various forms of ammunition, now known as the Niblick projectile, coming from Picatinny.

Launchers for the Niblick projectile at Springfield Armory from 1952 into 1955 concentrated on muzzle attachments for the M1 Garand service rifle. These launchers used a blank cartridge to propel a Niblick projectile much like a standard rifle grenade. Designs ranged from a simple tube to a complex 8-round semiautomatic launcher attachment that had a circular magazine holding the projectiles. None of the designs had much advantage over the standard rifle grenade and did not show enough promise for further development.

The Niblick projectile used in most of the muzzle launcher attachments was a drag-stabilized round with an extending skirt that spread out behind the fired projectile. A spin-stabilized Niblick projectile, resembling a fat bullet, was found to have much more promise in terms of accuracy. A cartridge design with a self-contained propellant was needed to further develop the potential of the Niblick projectile.

To fire the very large Niblick projectile from a cartridge case, the standard method of simply filling the case with propellant would not fit the needs of the project. When a standard small arms cartridge is fired, the projectile receives a very violent push from the rapidly burning propellant that gradually lowers in pressure as the projectile moves up the barrel. Using the standard cartridge system with the Niblick projectile would create several recoil problems, eliminating the possibility of a shoulder-launched weapon. Lowering the velocity of the Niblick projectile to allow a shoulder-fired weapon would cause most propellant powders to burn erratically at best, ruining accuracy from round to round, and badly cut back on the effective range of such a system.

During World War II, the Germans had faced a similar question, but for different reasons. The German question was how to build a worthwhile antitank weapon that would be lightweight, use few critical materials, and still have range, accuracy, and lethality. The use of a rocket projectile was ruled out due to an inherent lack of accuracy at long range and a very high consumption of fuel when compared to projectile weight.

A new internal ballistics principle, the “Niederdruck” or high-low pressure system was developed in Germany during WWII and was used by Rheinmetall-Borsig to solve the antitank weapon question. In the high-low pressure system, a relatively small amount of propellant is burned in a high pressure chamber until it reaches a threshold pressure and ruptures a seal. With the seal ruptured, propellant gases bleed through small holes in a metal plate into the low pressure chamber where they bear on the projectile. When fired, pressures in the high pressure chamber reach the 30-40,000 psi range while the low pressure chamber maintains a reasonably steady 3,000 psi. The high pressure chamber allows the propellant to burn completely and efficiently. The low pressure chamber gives the projectile a steady push with the pressure curve having a flat, almost optimal, line.

The steady push of the low pressure portion of the high-low system gives a useful velocity to the projectile but also allows for a more fragile projectile to be used than that of a regular cannon. The low pressure also gives a low recoil impulse but is very consistent for accuracy. The major stress of firing is in the high-pressure chamber so the barrel and resulting support equipment for the weapon can be made much lighter.

The German weapon that fielded the high-low pressure system was the Rheinmetall 8cm Panzerabwehrwerfer 600, or PAW 600. The PAW 600 fired a fin-stabilized, hollow-charge round that would penetrate 5.5 inches (14 cm) of steel, out to an effective range of 600 meters. the smoothbore weapon had a light barrel with only the breech section requiring heavy walls to withstand firing. Set up for action the PAW 600 only weighed some 1,389 pounds (630 kilograms) while a conventional 5-cm Pak 38 cannon weighed 2,205 pounds (1000 kilograms) and only had some 400 meters additional range with much less penetration.

Though considered revolutionary in concept and the only major ballistics advance of the war, the high-low pressure principle was not developed further in the years following World War II. In the 1952-53 time period, Picatinny Arsenal revived the high-low pressure system to propel the Niblick projectile in a self-contained round of ammunition.

The high-low pressure cartridge case was made of aluminum and was unique in its design. The center of the cartridge case was the high pressure chamber, a thick walled extrusion in the center base of the case. Spaced around the side of the high pressure chamber are six precise vent holes. The inside of the high pressure chamber is sealed with a thin brass cup that contains the powder charge and closes off the vent holes. The bottom of the cartridge is closed off with a thick base plug that holds a percussion primer.

When the 330 milligram (5 grain) propellant charge of M9 smokeless powder is ignited by the percussion primer, it builds up a pressure of 35,000 psi while burning. When the 35,000 psi point is reached in the high pressure chamber, the brass seal ruptures and the propellant gases bleed out into the low pressure chamber where they are reduced to a pressure of 3,000 psi. The 3,000 psi pressure moves the projectile up the barrel at a relatively slow rate, maintaining close to full pressure throughout a 14-inch barrel length. The Niblick projectile left a 14-inch barrel with a muzzle velocity of 250 feet per second and a right-hand spin of 3,700 rpm due to the rifled barrel.

The self-contained Niblick round kept a relatively low bore pressure in the launchers when compared to standard ammunition. The only point of high pressure stress when firing the round was taken up by the high-pressure chamber itself. These facts allowed the barrels of the various Project Niblick launchers to be made of aluminum. The low muzzle velocity also prevented any of the launchers from having excessive recoil even though a very large and heavy projectile was being launched for a hand-held weapon.

A number of launchers for Project Niblick were produced at Springfield Armory in 1953 under the direction of the project director, Cyril Moore. Two specific designs of launchers for the Niblick round showed considerable promise. One device was a simple shotgun-like fixture for determining ballistic data for the complete Niblick round. The other launcher was designed to fire six rounds semiautomatically. This was the first of the Project Niblick weapons that was a dedicated, shoulder-fired system. With a large rotating cylinder, the device acted much like a shoulder-fired revolver. Though the idea of semiautomatic fire held promise, the first device was found to be unsuitable for military use.

In the 1954-55 time period, the focus at Springfield Armory was on utilizing the complete Niblick round, though there was still some experimentation with the earlier types of projectiles. At this time, the S-3 launcher, a single-shot, break open, shoulder fired device with a rifled barrel was produced. This device greatly resembled the Federal Laboratories tear gas gun that was popular with police departments at the time but with a more complex sight and a forward hand grip.

A more complicated launcher that had semiautomatic capability was developed and under study by 1955. Identified as the S-6 strip-type shotgun, this was the first weapon to use a semiautomatic capability built into a conventional shotgun format. The S-6 used a harmonica-like strip of three Niblick rounds, each held in its own firing chamber, and feeding through the side of the receiver to give a semiautomatic fire capability. As each round was fired, a spring would drive the strip clip through the receiver until it indexed on the next loaded chamber. This form of launcher met with high approval in the conferences between Springfield Armory and Army Ordnance personnel and effort was put into refining the design.

A second generation semiautomatic S-6 launcher was available within a few months of the first model being accepted for development. Shortcomings from the first S-6 were eliminated in the second generation design. Further work was needed to meet the military needs of such a weapon system and study continued on the design. Other launchers were examined, including large flare-gun like pistols, to use the Niblick round, but none of the designs met with much success.

Later in 1955, the experimental Project Niblick weapons were due to be tested by the Army Infantry Board. Lieutenant Colonel Roy E. Rayle, the Small Arms R&D Chief at Springfield Armory, suggested further development go into another single shot launcher like the earlier S-3 design. Instead of developing a new design, Rayle suggested an already existing pattern, such as the Stevens Model 220 hammerless shotgun with a top-mounted safety and release lever, be modified to fire the Niblick round. The advantages of such a design would be the simplicity of operation and ease of training to recruits.

Lieutenant Colonel Rayle’s suggestion was followed and a second launcher was developed along the lines of the S-3, this one identified as the S-5 shotgun. The S-5 was the first attempt to build a Niblick launcher that followed the lines of a conventional, single-shot, sporting shotgun. The lines of the S-5 remained simple and the mechanism straightforward. Further development continued on the design especially on the shoulder stock and sight configurations. An immediate drawback to the S-5 that limited its appeal to the Army personnel was that the system was single-shot only.

During testing, the S-6 repeating grenade launcher was found to have problems with accuracy and was considered awkward to handle and operate. These problems were quickly traced to the harmonica magazine. A lack of a positive seal between the mouth of the magazine and the rear of the barrel caused propellant gases to slip though the gap. This caused irregular muzzle velocity in the S-6 weapon and greatly limited the firing accuracy of the system. The much simpler S-5 launcher was favored by the Infantry Board testers. A decision was made to try and correct the problems with the S-6 launcher in order to retain the semiautomatic capability while retaining the S-5 design in reserve.

By 1958, the S-6 design had evolved into the T148E1 and T148E2 launchers. The T148E2 design was more complicated than the E1 as it incorporated a break-open design to help seal off the barrel/magazine gap. The greater number of components in the T148E2 design eliminated it from further development in favor of the simpler T148E1 pattern. A limited pilot-line production of 200 T148E1 launchers was conducted between 1 January and 30 June 1958 to supply a number of the weapons for field testing and further evaluation. The gas bleed-off at the chamber/barrel gap still caused an unacceptable loss of accuracy and the T148 project was terminated after 1 July 1960.

A conference of Army and Springfield Armory personnel decided the S-5 design, now known as the XM79, should be reactivated. US Army Infantry Board testing determined that a new sighting system should be designed and a few shortcomings of the XM79 be corrected before acceptance. The new sight design was ready by October 1959 and all XM79 launchers produced up to that point refitted with the correction. On 15 December, 1960, the M79 was officially type-classified and adopted by the US Army. Further production difficulties in producing the complicated rear sight limited weapon availability for some years after adoption.

By 1965, the M79 grenade launcher was in full production and available for issue to all of the services.

After the approval of Form 1 from ATF you can acquire and attach a barrel to your new M-203 or M-79. Under no circumstances should you obtain a barrel before the Form 1 is approved, that would be “Constructive Possession of an unregistered Destructive Device”. That is a felony! Wait until you have that approved Form 1 before getting a barrel! Building your own has two advantages. The first is that you can avoid the hassle of finding a Type 9 FFL Dealer (Or Type 10 manufacturer, or Type 11 Importer) in your State that legally can transfer a registered Destructive Device. Most states don’t even have one. The second advantage of building your own is that it’s cheaper on the wallet or purse and you save $200.00 for one less transfer tax. Class 3 Dealers have been allowed by the ATF to transfer Destructive Devices on a very small scale, rumor has it to be 4 items or less per year but I have never come across the magical number in any publication.

One of the first challenges for the recreational shooter to overcome besides the initial cost of the Destructive Device which can range from $2,000.00 to $10,000.00 in today’s market is ammo. You will need to learn to tell the difference between Hi Pressure and Low Pressure 40mm ammunition, not knowing the difference can be fatal. One easy way to tell the difference is to look at the rotating band above the shell case… Hi Pressure rounds will have a copper rotating band, designed for the steel barrel of a Mark-19 40mm machinegun. Do not even attempt to chamber one of these rounds in an M-79 or an M-203.

The copper rotating band will stick inside the aluminum barrel and it will blow you and the weapon up when you pull that trigger. There is a major difference in propellants and velocities, as previously covered in SAR.

Some types of ammo that you can shoot are flares, smokes, gas, Flechette, buckshot, reloadable ‘Bee Hive,” practice, non lethal rubber pellets and bean bag rounds. Also there are 12 gauge adapter cartridges out there and your choices are unlimited. Many ask if they can shoot 37mm flares or gas rounds in a 40mm and that all depends on the thickness of the base of the 37mm… some of the new 37mm flare ammo have a base that is twice as thick of the 40mm cartridge and it will not chamber properly. If you find some old W.W.II flares, try wrapping masking tape around the case near the base about one and a half times and it won’t rattle.

From time to time some generous soul will sell off a case of 40mm practice rounds because they are leaking orange chalk all over the place. These practice grenades can be stabilized with a tube of super glue and a damp rag. Just run a bead of super glue between the blue ogive and the zinc rotating band and immediately wipe off any excess glue with the damp rag. It also helps to keep some acetone or the wife’s fingernail polish remover handy to loosen those glued fingers.

Most guys who try to reload the white nylon M-212 cases make the mistake once of buying the wrong box of blank cartridges. What you are looking for is 38 Smith & Wesson Blanks from Winchester coded “38BLP” on the box. They are shorter than the standard 38 Special Blanks coded “38SBLP,” the M-781 practice round uses only the short Smith & Wesson Blanks “38BLP” as a propellant. Please always remember to wear a pair of good shooting glasses when firing off practice rounds, some of the surplus is old and an occasional blue ogive may disintegrate upon leaving the barrel and leave you looking like the Great Orange Pumpkin, it will not hurt you -so protect those eyes! And laugh it off. I can assure you that all those around you will be laughing too.

Some of the misconceptions about recreational 40mm among the public is that all of the grenades are High Explosive, all are illegal to possess and all rounds must have a $200.00 tax paid on them. Not true. Only the HE rounds require the $200.00 transfer tax stamp on each round. Easily identified with a gold or orange ogive, these also require a Federal Explosive permit and fall under strict shipping and storage guidelines. That’s not even considering that you will need the signature of your local Law Enforcement and you have to report back to the ATF that you blew the silly thing up! There are just too many gun laws. Any other 40mm round is legal to own or sell. If you intend to manufacture 40mm rounds for other than your own personal use, you will need a Federal License to do so.

A word of warning on the ammunition- the M781 practice round has a heavy metal driving band in it- you should never point ANY firearm at another person, or at anything you don’t want to shoot, but these “Marking” rounds can be fatal if they hit a person- there have been many instances in the military of someone shooting a “Buddy” with a “Paint” round, and breaking an arm, or ribs, or even worse. While we have fun with these, they are not toys.

You will find in your search for shootable 40mm ammo that there are over a dozen different companies that currently manufacture new ammo. But you will find them reluctant to sell to the still Free American Citizen regardless of having paperwork that your 40mm is legally Registered with the Federal Government. Thanks to the work of a few liberals in Insurance Companies and the overzealous Jackboot, most will not sell to the public and limit their sales only to Law Enforcement Agencies and the Military. Sure is ironic that a manufacturer that is in the business to make a profit, would refuse a sale to a cash paying customer that has every legal right to possess their product and can provide documentation proving so. Rather Un-American, don’t you think? There is a problem with the Department of Transportation’s regulations, considering these to NOT be ORM-D small arms ammunition because of the caliber, and some manufacturers will sell and ship to individuals with a Federal Explosives license, or a licensee who will accept these for them.

So what does all this have to do with Recreational 40mm? Half of the Recreation is finding cheap shootable ammo, the other half is actually possessing and shooting a 40mm on a regular basis. One must learn the fine art of Kentucky windage, with a maximum range of around 350 yards, you need to be good at judging distances or own a rangefinder. Wind will negatively affect your accuracy as well as your barrel length, one instance where size/length does matter. It is essentially a hand held mortar and can be fired for effect from the ground, either direct or indirectly by using the marked sling method. On rare occasions you will find a couple of “Thumpers” or “Bloopers” or “Elmer Fudd” guns at a shooting match. Enjoy the fun, its only a gun.

Automatic grenade launchers (AGL) have been a mainstay of light infantry support weapons since the Vietnam War when the US Navy’s 40x53mm Mark 19 was introduced for use in riverine warfare operations in the Mekong River delta. Since then, there has been a number of first generation 40mm AGLs produced. All are similar in concept, are relatively heavy with an overall system weight of 50 kg or more and all have relatively simple optical sights. Saco Defense, however, is in the final stages of development of what promises to be the next generation of AGL. This new AGL, called Striker, is presently under consideration for adoption by US special operations forces and will shortly be available for international sales. SAR’s intrepid reporter was recently afforded the opportunity to be the first journalist to actually fire the Striker at Crane Division, Naval Surface Warfare Center, where the weapon is undergoing test and evaluation by the US military.

The Striker was developed as a private venture by a consortium consisting of Saco Defense (gun and overall system integration), Computing Devices Canada (fire control) and NAMMO Bofors (programmable ammunition). The overall design goals for the weapon were to develop a new generation 40mm AGL that provided improved lethality and suppression capability, significantly lighter weight, enhanced reliability and increased lethality, combined with reasonable cost. It was with these goals in mind that we approached our informal evaluation of the Striker.

There are several features that differentiate the Striker from all other currently available AGLs. The Striker is considerably lighter than any other currently available AGL. The Striker has a computer controlled fire control system developed by Computer Devices Canada that not only automatically sets superelevation and windage, but also programs the air burst munition developed by Nammo Bofors and significantly enhances the probability of a first burst hit. We will discuss these features in detail below. Table 1 provides a comparison between Striker and currently available 40mm AGLs.

The Striker operates via delayed blowback using a toggle mechanism to delay bolt opening sufficiently long for pressures to drop to a safe level. Saco did not allow photography of the interior of the Striker at this point due to patent sensitivities. We were, however, permitted to examine the gun’s interior and field strip it. The overall simplicity of the Striker and its ability to be field stripped, to include barrel removal, without the use of tools is impressive. The Striker fires from the closed bolt and is fed from a standard disintegrating link belt via a sprocket driven by the recoiling parts. Ejection is straight down. The round counter on the gun we tested indicated that it had fired nearly 20,000 rounds. According to Saco representatives and Crane personnel, overall weapon performance has been excellent and will equal or exceed that of the Mark 19.

The reader will note that the “full-up” Striker with fire control and tripod in place weighs less than the gun alone in some other available systems and weighs dramatically less than any other currently available AGL configured with sights and tripod. Striker’s weight saving has been accomplished in several ways, while at the same time reducing recoil by 60 per cent compared to that of the Mark 19. The toggle link delayed blowback system, for example, allowed bolt weight to be reduced by 11lb (5kg) in comparison to that of the Mark 19. Toggle link delayed blowback has been widely used in the past and is in itself no great technological breakthrough, although its use in Striker is an ingenious application of the technique. A second factor that reduces recoil is the bi-directional hydraulic buffer that operates in both recoil and counterrecoil to reduce felt recoil and stabilize the gun. The buffer, which acts as in internal soft mount, can also be adjusted to vary the Striker’s cyclic rate from approximately 230 to 300 rounds per minute.

All unstressed components of the Striker are made of either light alloy or polymer. The receiver of the Striker, for example, receives little stress and is made of aluminum, while the top cover receives no stress whatsoever and thus is of polymer. The reciprocating components ride on steel rails in the receiver. In comparison to the Mark 19, the total number of parts in the Striker has been reduced by 33 per cent. Essentially, the entire Striker system was developed by innovative application and integration of existing technologies. This not only helped to achieve the weight and reliability goals, but also enhanced the achievement of cost goals. The Striker is light enough that the entire system can be easily carried and placed into action by a two-man crew, although a third man is desirable to carry the 40mm ammunition. The lightweight tripod collapses into a very compact and convenient package for transportation. Extending or collapsing the tripod takes only a matter of seconds.

The Striker is fully STANAG compliant and fires all standard 40x53mm ammunition, although the system is optimized for the programmable air burst munition. The Striker is made to be as safe as humanly possible for the user. The manual safety is configured in such a way that its position can be determined by touch. The weapon will not fire if the barrel or buffer are incorrectly installed. The backplate cannot be removed if there is a round in the chamber. Since removal of the backplate is necessary to field strip the Striker, the gun thus cannot be disassembled while loaded. In addition, the firing pin is blocked until the bolt is in the fully closed position. Short recoils are precluded by a ratchet mechanism. As previously stated, the gun has a built in round counter to indicate scheduled maintenance.

Another innovative element of the Striker is the weapon’s computer controlled fire control system, which allows the gunner to achieve a high percentage of first burst hits, rather than having to “walk” rounds onto the target as required with other AGLs. The 8x-magnification sight uses video image processing and ballistic computer technology to enhance target acquisition and first round hit probability. The sighting system also allows Striker to achieve a greater effective range than current systems. All current systems have an effective range of approximately 1,500 meters, but Striker’s effectiveness is multiplied by its accuracy. The sight incorporates a Gen III Image intensifier for night operations. The computer provides a full ballistic solution, can be used with virtually any 40x53mm cartridge, has air temperature and barometric pressure sensors, automatically compensates for ammunition temperature, senses cant and angle and is self-testing. In practice, all the gunner has to do is range the target using the sight’s laser range finder to designate his target. He then moves the corrected sight aim point to coincide with the target he has designated and the weapon can then be fired with virtual assurance of a first burst hit. The computer automatically computes superelevation, the weapon’s elevation angle above the line of sight to ensure that the projectile hits the target. Not only is this system simpler to use, it allows targets to be engaged much more quickly than with any existing system. In addition to rapid target engagement, the ballistic computer provides the ability to predesignate up to eight targets and store them in the computer’s memory. These targets may subsequently be engaged regardless of optical conditions. The ballistic computer further allows the gunner to prepare electronic range cards with lateral limits to automatically prevent engagements outside the range “fan,” although this feature can be manually overridden. Future upgrades to the computer fire control system include automatic calculation of the speed of moving targets and incorporation of a global positioning system into the fire control computer to allow automatic indirect firing.

The ballistic computer also provides a direct interface with the programmable ammunition developed by NAMMO Bofors. The programmable ammunition, while extremely innovative, again is manufactured using a maximum number of available components. The warhead, for example, was designed by Diehl with Bofors fuzing that provides air burst, point detonation and self-destruct, while the propulsion element is a standard NICO component. As ammunition is an integral element of accuracy, along with the gun itself, NICO’s propulsion system is specifically designed for low dispersion. The NICO cartridge case to projectile interface is threaded rather than crimped to provide a consistent release at a predetermined pressure to reduce dispersion. The air burst warhead is electronically programmed by the ballistic computer just prior to firing as the rangefinder determines the range and computes the trajectory and time of flight to the target. Use of an air bursting munition allows engagement of targets in defilade or behind obstacles. The lethal area of the 40mm air burst round is approximately 100 square meters.

Our overall firing impressions of the Striker were extremely favorable. We fired the weapon from a pedestal mount and found it to be easy to control and pleasant to shoot. We were able to use the computer fire control to quickly engage targets after only a few minutes’ orientation and “dry firing” practice. The cyclic rate was set to approximately 230 rounds per minute, allowing easy burst control or even single shots if desired. We were consistently able to achieve first round hits with the Striker by simply engaging the range finder, matching the gun to the sight’s indicated point of aim and pressing the trigger. With very little additional training, we could easily have made use of the remainder of the fire control unit’s sophisticated capabilities. We fired two containers of 48 rounds each without incident. The first rounds in each burst hit precisely where we aimed, with the remainder of the burst clustered closely around the initial hit, consistent with Saco’s dispersion claims. Had we been firing high explosive rather than training rounds, we could have easily destroyed hardened targets with very few rounds. We did not notice any appreciable recoil through the “hard” pedestal mount; had we been firing any other AGL, an external “soft mount” would have been a virtual necessity. Striker’s inherent low recoil and light weight will assuredly simplify adapting the weapon to vehicle mounts. We did not fire the Striker from the lightweight tripod ground mount, but given the lack of felt recoil on the rigid pedestal mount and Striker’s internal soft mount, we believe that the eight pound (3.6kg) tripod will sustain the weight and recoil of the gun.

In sum, we liked the Striker. We tend to approach all manufacturers’ claims with a very jaundiced eye, but in the case of the Striker, our “hands on” experience, albeit brief, indicates that the weapon will probably live up to its claimed performance levels. In closing, we should point out that the Striker is not yet a fielded system. It is undergoing final developmental testing and is currently scheduled to enter production in late 2000 with initial deliveries shortly thereafter. In Europe, the Striker is sold by Bofors/Carl Gustav as the CG40. In the remainder of the world, except Canada, it is sold by Saco under the Striker name. Canadian sales are handled by Computing Devices Canada. Those seeking further information on this system should contact one of these firms.