ABOVE: As part of the development of under barrel grenade launchers, LWL fabricated this mount for Colt’s XM148 grenade launcher to allow it to be fitted to the M1 carbine. (U.S. Army)

After the end of the Second World War, the United States military, the Army especially, saw its mission as one of countering potential Soviet aggression. If this were to come, the most likely battlefield would be in Northern Europe. With the Soviet Union’s acquisition of nuclear weapons the two world powers settled into the Cold War. Though a major land war between the two in Europe would have been catastrophic, other fronts presented more potential. By supporting insurgencies around the world the Soviet Union could needle the United States without risking nuclear war.

It was in response to these threats that the U.S. Army created the Limited War Laboratory (USALWL or just LWL) in 1962 at Aberdeen Proving Ground in Maryland. Other U.S. Army development activities were largely focused on the potential for open warfare with the Soviets. Insurgents on the other had presented an almost completely different adversary, against which the full conventional power of the U.S. military could not always be directed.

The LWL was directed to develop and provide new and improved weapons and equipment to U.S. forces who might find themselves engaged with these forces. At the time, the U.S. was steadily increasing its involvement in Southeast Asia, for instance. A number of insurgencies threatened U.S.-friendly governments in the region. As time went on, the LWL would become very much involved in development equipment for U.S. forces in Vietnam, where counter-insurgency was the name of the game. Its projects dealt not just with weapons, but also various pieces of equipment designed to help with or improve communications, logistics, and even simple survival in the field.

A 40mm multi-shot projectile developed for the M79 grenade launcher by the LWL. Work on this reloadable adapter, capable of firing eighteen .22 caliber rounds simultaneously, was continued by Frankford Arsenal. (U.S. Army)

In the aftermath of Vietnam, as the U.S. military as a whole worked hard to return to what it understood as traditional warfighting, work at the LWL steadily slowed down. It was also subjected to increasing reviews of its basic function and necessity. It had already been named the Land Warfare Laboratory in 1970 in an attempt to distance the activity from the fighting in Southeast Asia and broaden its scope. The acronym remained the same. In February 1974, however, the decision was made to inactivate the LWL and on June 30, 1974 the laboratory closed its doors. What follows here is a look at some of the small arms projects the LWL had a hand in during its twelve years of operation.

Handguns

LWL’s first handgun projects were in response to the issue of locating, exploring, and neutralizing tunnels used by insurgents. LWL had itself identified this as a potential threat, but had also received requests for equipment to help neutralize such tunnels from Military Assistance Command – Vietnam (MACV). Insurgents in South Vietnam proved to be adept in creating large underground tunnel networks that served as bases for their operations. These tunnels were often booby-trapped and could be extremely narrow in places, meaning that personnel exploring them, called “tunnel rats,” had a definite need for specialized equipment.

Among these requirements was one for a specialized firearm that suited the environment. Long arms were out of the question and the report from a standard .45 caliber M1911A1 pistol could be deafening to all involved if used inside the tunnels. In 1966, LWL developed a kit for tunnel rats, which included a specially modified .38 caliber revolver with a sound suppressor. Six such kits were shipped to Vietnam, where they were evaluated by the Army Concept Team in Vietnam (ACTIV).

LWL’s Adjustable Ranging Telescope mounted on an M14 rifle. This later became the scope used with the M21 sniper rifle. (U.S. Army)

In addition, before ACTIV’s evaluation had even begun, a new request was submitted for over four hundred and fifty such kits. LWL subsequently developed what they called the Tunnel Security and Intelligence Team Protective Equipment kit, the successor to the original tunnel kit. The recommendations from ACTIV’s evaluation of the six kits sent to Vietnam were incorporated in the development process. Among the improvements was the replacement of the modified .38 caliber revolver with a suppressed semiautomatic .22 caliber High Standard pistol. These new kits were turned over to U.S. Army Natick Laboratories, which had been designated as the parent agency for the new request, and sent to Vietnam in May 1968.

Still, it became clear that a dedicated weapon was needed for the kits. LWL subsequently began work on such a project, contracting the AAI Corporation to design a Tunnel Weapon. The resulting weapon was a highly modified .44 caliber Smith and Wesson revolver. The snub-nosed weapon fired a specially designed “silent” cartridge featuring a captive piston that contained the smoke and flash when it was fired. With this new round, the revolvers were about as quiet as the High Standard pistol. The cartridges were also loaded with fifteen tungsten pellets in a plastic shot cup. The shotgun-like design was intended to improve hit probability even by inexperienced shooters in the close-quarters environment of a tunnel and to improve lethality over the .22 caliber weapon.

Ten weapons and a little under a thousand rounds of ammunition were shipped to Vietnam in 1969, where they were distributed by ACTIV to units of the 1st, 23rd, and 25th Infantry Divisions. Though intended for tunnel work, the weapons were also obtained by long-range reconnaissance units and utilized during ambushes of enemy personnel. They were also found to be useful when clearing out bunkers and houses. ACTIV recommended that the weapon be refined and issued to regular infantry companies and Ranger companies, as well as to tunnel rats. Between January 1970 and October 1972, AAI worked under contract to LWL to refine the design of what became known as the Quiet, Special Purpose Revolver (QSPR). However, with the end of Vietnam, the requirement for the QSPR dried up and it was never widely issued as had originally been envisioned.

The disposable plastic magazine for the M16A1 developed by the LWL. This magazine was found to be too fragile for combat use. (U.S. Army)

Between June and December 1967, the LWL also evaluated the performance of a unique weapon, the Gyrojet, at the request of MACV. The Gyrojet, developed by Arthur Biehl at the company MB Associates, reflected a certain early 1960s futurism and was intended to revolutionize small arms development. Instead of a traditional cartridge, the rounds for the Gyrojet weapons were miniature rockets. According to MB Associates, the new rounds allowed the weapons to be silent and even fired under water.

In practice, however, the weapons were found to be mechanically complex, unreliable, and inaccurate. LWL tested the pistol variant of the weapon against a standard issue M1911A1 pistol, a .22 caliber Colt pistol, and the silenced .22 caliber High Standard pistol that was included in the LWL’s tunnel kit. In addition to finding the Gyrojet weapons to be unreliable during testing, LWL also reported that the flash from firing was excessive and that the weapons were louder than the silenced High Standard.

Still, some weapons were reported to have made their way to Southeast Asia where they were evaluated in the field by MACV’s secretive Studies and Observation Group (MACV-SOG). In 1970, MACV-SOG also supplied LWL with ten Walther PPKS pistols, five each in 7.62mm Browning and 9mm Browning, as part of the Silenced Pistols and Rifle (SPAR) program. In 1971, LWL returned four PPKS pistols in each caliber with new barrels capable of mounting a sound suppressor to MACV-SOG for evaluation in Southeast Asia. The results of the evaluation are unknown.

The products of the Silenced Pistols and Rifle program LWL conducted for MACV-SOG, including suppressed PPKS pistols in two calibers and suppressed AK-47 type weapons. (U.S. Army)

Rifles and Carbines

LWL’s work with rifles began in 1963 when it responded to a request to develop a sighting system for rifles and other small arms. This sighting system would be provided to Special Forces units to help in their core mission of training indigenous forces. Many of the groups Special Forces units were working with at the time in Southeast Asia had limited experience with modern firearms. LWL subsequently contracted General Precision to design a sight making use of the image correlation aiming method, which could be substituted for a weapon’s rear sight. LWL reported that the resulting design, which obviated the need for a front sight as well, showed promise, but was not rugged enough for combat use.

Following on from this project, LWL initiated work in 1964 on a compact rifle sight that would be rugged enough for combat use. This produced a reflex-collimator sight capable of being mounted on the M1 and M14 rifles. Accurate shot groups for both weapons were achieved at ranges from fifty to four hundred yards during engineering design testing. However, during military potential testing by the U.S. Army Infantry Board, a number of deficiencies were identified, including an issue of parallax. The durability of the sight also remained an issue.

The effort was terminated in 1967 after it was decided that the cost in time and money to correct the problems was prohibitive, especially given that the U.S. Army itself had no formal requirement for such a device, its development having been specifically for indigenous forces trained by Special Forces teams. However, work in a similar vein continued and in January 1967, LWL fabricated what it called a Rifle Night Sight by taking half of a pair of 6×42 binoculars and mounting it on a bolt action target rifle. The binoculars, produced by Kollsman Instrument Corporation, featured an illuminated reticle, which it was felt would provide help in nighttime aiming. Prototype mounts were developed for the M14 and M16A1 rifles, but still without any formal requirement, work did not progress beyond this stage.

After observing field modifications to the M79 grenade launcher, LWL developed a purpose build Hand Held Grenade Launcher kit for the weapon. Notable is the pistol grip with guard to prevent the user’s hand from slipping during firing. (U.S. Army)

Around the time work was first starting on the compact rifle sight, the Joint Research and Test Activity (JRATA) in Vietnam requested that LWL look into fabricating mounts for the T1 infrared sight for various small arms. The T1 was a first generation active infrared weapons sight that had been developed by the Army’s Engineer Research and Design Laboratory (ERDL). However, ERDL’s sight was only capable of being mounted on the M14 rifle. These weapons were not in service with the Army of Republic of Vietnam (ARVN) when JRATA made the request in 1964.

Insurgents in South Vietnam owned the night and there were various requirements for night observation devices and weapon sights. JRATA’s idea was to see if the T1 could be adapted to weapons the ARVN did have in service, like the M1 rifle and M1 carbine. In the end, LWL fabricated twenty sights each for the M1 rifle and M1 carbine, as well as another twenty for the XM16E1 rifle. These were shipped to Vietnam for evaluation, where the T1 sight was found to be heavy and bulky, & not generally suitable for widespread use by the ARVN.

LWL also developed a mount for the M14 rifle allowing for the mounting of a conventional commercial Bushnell Scopechief II 3-9x rifle scope. This was in response to a request in 1965 for increased sniper capabilities for U.S. Army infantry units. A Colt Realist 3x scope was also procured as part of the program. The scopes for the M14s, along with cheekpads designed for the M1C sniper rifle, were sent to South Vietnam for evaluation in late 1965, and Colt Realist scopes were also subsequently evaluated there. In December 1965, LWL began work on an Adjustable Ranging Telescope (ART), which subsequently became the scope used on the dedicated sniper variant of the M14, the M21. LWL also developed a Reticle Illumination Adapter Kit (RIAK) for the ART in 1969, which would allow for an illuminated reticle to be rapidly incorporated into existing ARTs. However, work on this was canceled when it was decided that illuminating the reticle helped little in the more critical issue of identifying targets at range.

An adapter allowing standard anade launcher, developed by the Olin Mathieson Chemical Corporation under contract to the LWL. (U.S. Army)

In August 1967, LWL initiated work on a Silent Sniper System as part of continued work to help improve sniper capabilities. AAI Corporation was contracted to produce the system, which consisted of a modified Winchester 70 bolt-action rifle with an integral sound suppressor. The new rifle was chambered for a special .458 subsonic round modified from a .458 magnum cartridge and using a five hundred grain steel jacketed bullet. It was estimated that the weapon had no audible firing signature beyond one hundred yards. LWL’s ART scope was the standard optic for the rifle, but a provision was also made for mounting a Starlight Scope night vision device. Five rifles and ammunition were sent to Vietnam for tests in 1971. The results of the evaluation are unclear, but LWL was only responsible for the initial development of the system. After delivering the weapons, LWL reported that any further development would be handled by the U.S. Army’s Weapons Command.

Between 1966 and 1969, LWL also worked on the development of a lightweight plastic magazine for the M16A1 rifle. Though the existing aluminum magazines were intended to be disposable, this still came at a relatively high cost. It was hoped that a plastic magazine could be produced at a cost that would make it truly disposable. The Army had also identified other potential benefits to a plastic magazine. For one, metal magazines in pouches rattled together, creating noise that could give a unit away. The jungle environment in Vietnam was also leading to a corrosion problem. Lastly, when troops discarded the magazines as intended, it potentially gave insurgents a ready supply of aluminum with which to build things, including boobytraps. In the end, given the material available at the time, the magazines produced by LWL were not as durable as the existing metal ones under any conditions, and work was halted.

LWL’s backpack feeding system for the M60 machine gun. Clearly visible is the reel type drum and flexible feed chute. (U.S. Army)

LWL work on rifles and carbines was not limited to work on standard Army systems either. As part of the previously mentioned SPAR program, MACV-SOG supplied six AK-47 type rifles to the LWL. LWL modified the AKs to allow the mounting of a sound suppressor by relocating the front sight and returned them to MACV-SOG for evaluation. As with the silenced PPKS pistols provided for the SPAR program, the results of this evaluation are unknown.

Also worth noting is that LWL developed a short-range radio that fit into a specifically modified stock for an AR-15/M16 type rifle. The idea was that the point man of a patrol could communicate with the rest of the patrol without taking his hand off of his weapon. The Advanced Research Projects Agency (ARPA) had fabricated a version capable of transmitting tones only in 1963. In 1966, JRATA asked LWL for an improved version that would allow for full voice communication. A prototype compatible with the AN/PRC-25 infantry radio was developed and built by the Ryan Aeronautical Company under contract to LWL. However, the program was subsequently canceled in February 1967 on the recommendation of the commanding general of U.S. Army, Vietnam. Some of the Ryan Model 529 transceivers were tested by the U.S. Marine Corps, who also did not adopt the system.

Machine Guns

LWL’s work with machine guns was limited. Between 1962 and 1963, LWL conducted the actual tests at Aberdeen Proving Ground as part of an ARPA program on increasing the utility of .50 caliber machine guns in a jungle environment as part of Salvo Squeezebore program. The tests were conducted using ammunition specially developed by the RICA Corporation, which were fired from .50 caliber M2 machine guns with modified barrels. When fired, the five projectiles in the round, each weighing one hundred and forty grains, would travel down the barrel and be “squeezed” down to approximately .30 caliber, achieving a muzzle velocity of over three thousand feet per second. The tests concluded the system was not suitable for combat use, though the concept itself was deemed promising.

A posed photo showing soldiers demonstrating LWL’s Tunnel Kit. The soldier on the left has the suppressed .38 caliber revolver that was included with the kit. (U.S. Army)

LWL also supplied sight brackets for the M1919A4 machine gun to allow the mounting of the T1 infrared sight as part of the effort previously mentioned. Ten mounting brackets were sent to Vietnam for evaluation, where the decision was eventually made not to pursue use of the T1 sight.

Perhaps most notable was LWL’s work to design a backpack ammunition feeding system for the M60 machine gun. After beginning work in May 1968, LWL developed an individual ammunition feeding device capable of being carried like a backpack with a capacity of four hundred rounds. The system weighed thirty-six pounds and consisted of a backpack frame, a reel-type feed ammunition container, and flexible feed chuting of the kind normally used on aircraft. The system was tested in all standard firing positions and was found to not restrict the gunner’s field of fire. Seventeen systems were shipped to Vietnam in 1969 for evaluation. Though the system was functional, it prevented the individual from carrying a standard backpack, limiting its utility when used on long operations away from established base areas.

Grenade Launchers

Some of the first work done at LWL with regards to grenade launchers was to work on the issue of personal defense for grenadiers. Individuals issued the M79 grenade launcher were limited in their ability to defend themselves in close quarters. The 40mm ammunition used was dangerous if used to close to the firer and was therefore designed with a safety feature that prevented it from detonating before traveling to a safe distance of between sixty and ninety feet. To provide some manner of self-defense capability, the U.S. Army also issued M1911A1 pistols to personnel issued the M79. This was clearly not an ideal compromise.

LWL’s Rifle Night Sight, fabricated from a half a pair of binoculars. This offered a cheap method of providing a sight with an illuminated reticle. (U.S. Army)

In 1964, LWL contracted the Olin Mathieson Chemical Corporation to produce an adapter for the M79 that would allow it to fire standard 12 gauge shotgun shells. The resulting design weighed eight ounces and consisted of a six inch steel barrel and outer plastic sleeve that could be inserted into the M79’s breech like a normal 40mm round. Tests were conducted with different chokes to determine which would produce the best shot pattern at close ranges. Standard two and three-quarters inch shotshells loaded with number four shot were used. Twenty units were subsequently procured for field tests with a finalized choke design and five were sent to Vietnam for testing.

It is unclear what the results of the field tests were, as LWL said it never received the results before it was ordered to halt work on the project in 1965. Work subsequently shifted to a multi-shot device similar in basic size and shape to existing 40mm rounds. In 1965, LWL developed a reloadable adapter that could simultaneously fire eighteen .22 caliber cartridges. LWL subsequently turned the program over to the Army’s Frankford Arsenal, which continued development, eventually abandoning the concept. Eventually, the U.S. Army adopted the M576 40mm cartridge, an expendable shotshell loaded with number four shot that utilized a modified 40mm cartridge case.

The experimental Silent Sniper System designed by AAI under contract to the LWL. Four of the specially designed .458 cartridges can be seen at the lower left-hand corner of the picture. (U.S. Army)

In spite of these developments, in Vietnam grenadiers and other personnel often modified the M79 to make the weapon more compact and as a result capable of being carried as a secondary weapon. LWL subsequently decided to see if a purpose built kit for a so-called Hand Held Grenade Launcher (HAGL) could be developed. The primary component developed under the HAGL program was an aluminum pistol grip. When individual soldiers cut off the M79’s stock then found that they would often sustain injuries when firing as their hand slipped up and hit the weapon’s safety. The pistol grip provided a flare that would prevent the shooter’s hand from slipping during firing. HAGL kits were subsequently supplied to the 5th Special Forces Group for evaluation in 1970. The decision to phase out the M79 in favor of the M203 grenade launcher mounted on the M16A1 rifle ended further work on the HAGL.

LWL was also involved in the development of under barrel grenade launchers leading up to the adoption of the M203. In March 1965, it conducted work to develop a mount for Colt’s 40mm CGL-4 grenade launcher, later designated the XM148, for the M1 rifle and M1 carbine. The M1 rifle mount, which attached to the barrel through the handguard and to the bayonet lug was determined to be overly cumbersome and work on that variant was terminated. The M1 carbine mount, attached at two points to the weapon’s barrel, was deemed suitable for field tests. Three XM148 grenade launchers and three mounts were provided to JRATA for tests in Vietnam.

The Compact Rifle Sight developed by LWL. This reflex-collimator sight unit was intended to help Special Forces personnel in training indigenous forces. (U.S. Army)

The field tests showed that the mount and weapon were not durable enough for combat use, a consistent problem with the XM148 that led to it not being adopted by the U.S. Army. In the end, the U.S. Army adopted the M203 grenade launcher developed by the AAI Corporation. This weapon was designed for mounting on the M16A1 rifle at two points on the barrel, but its positioning made using the front sling swivel of the host gun difficult. LWL was called on to design an adapter kit that provided an alternate front sling swivel to allow the weapon’s sling to be repositioned when the launcher was mounted.

In Summary

In its twelve years of existence, the LWL worked on a wide array of projects, including the weapons programs mentioned here. Many of the LWL’s products never reached widespread usage due to a variety of factors. Chief among these was that the 1960s was a period of revolutionary development in military technology, and in many cases the requirements had shifted or disappeared by the time development work on a specific project was completed. In addition, available technology and materials limited the usefulness of numerous products. For instance polymer magazines and reflex sights are now common and used by the U.S. military and others. The LWL also made a significant contribution to the development of what became the M21 sniper rifle, a system that remained in Army use well after the laboratory had ceased to exist, showing that all its efforts were not without success.