In January 1991, the U.S. Air Force’s 24th Security Police Squadron at Howard Air Force Base in Panama found itself in a predicament. The unit’s explosive ordnance disposal elements had a shortage of guns. For more than three years, the team’s request for four carbines had been on back order.

So the squadron sent a request up the chain to the Warner Robins Air Logistics Complex at Robins Air Force Base in Georgia asking for permission to use their own money to do the work themselves. Armorers at Howard would turn three M16s – with serials in the 300,000 range, dating them to the 1960s – into new carbines, called GUU-5/Ps.

Line drawing of the parts for the GAU-5/A, GAU-5A/A and GUU-5/P from a 1989 copy of the official technical order. (Air Force)

By the end of the month, Warner Robins gave the go ahead to the plans. The squadron just had to make sure that it changed the National Stock Numbers for the weapons in the logistics database to make sure everything evened out on paper. Otherwise, if something broke, they might get replacement parts for the older rifles instead of what they actually needed. The author obtained these messages and other records related to the GUU-5/P through the Freedom of Information Act.

The 24th was not alone in the desire for more modern weapons. Throughout the 1990s, Air Force units steadily converted older M16-type rifles and carbines into GUU-5/Ps. While they shared a common theme of having collapsible buttstocks and 14.5-inch barrels, the new firearms were often each a bit unique. Online, enthusiasts on message boards like ar15.com dubbed them “frankenguns” or “mixmasters” on account of the various features found from one gun to the next. The Air Force has been working to replace these conversions with new M4 carbines. However, official instructions still called for these guns as recently as 2014.

Born of need and limited resources, the ad hoc the nature of the GUU-5/P is not necessarily surprising. Historically, the Air Force is not widely known for their work on small arms. “No AF led small arms programs,” Col. Patrick Lopardi, then head of the Programs, Requirements and Innovations Division at the Air Force Security Forces Center stated bluntly in one 2009 briefing. Lopradi was explaining the state of the service’s combat arms program to attendees of the National Defense Industry Association’s International Infantry and Joint Services Small Arms Systems Symposium in Las Vegas, Nevada.

Another GUU-5/P with the M4-type barrel, but with a later model lower receiver (Air Force)

However, the Air Force actually has a long and complex history with the “black rifle.” While the U.S. Army had been ambivalent when they first examined the AR-15 in the late 1950s, the fledgling flying branch was soon taken with ArmaLite’s “space age” lightweight aluminum and plastic rifle. In particular, the company’s parent corporation Fairchild actively lobbied through then head of Strategic Air Command and later Chief of Staff of the Air Force, Gen. Curtis LeMay.

On July 4th, 1960, LeMay famously attended a party to celebrate Independence Day and the birthday of former Fairchild president Richard Boutelle. Boutelle and others made sure the general found time to blast some watermelons with an AR-15. Afterwards, LeMay campaigned to replace the Air Force’s aging World War II-era M-2 carbines with the much more modern gun.

Less than two years later, the Air Force became the first service to adopt the weapon. The Army followed suit and requested a variant with additional features – most notably a forward assist mechanism to push the bolt into battery if it didn’t seat correctly – known as the XM16E1. As a result, the Pentagon retroactively renamed the earlier AR-15s as XM16s, though both terms continued to be used to refer to the rifles. The services standardized these weapons as the M16A1 and M16 respectively.

After putting the full length rifles into service, the Air Force was quick to realize the utility of carbine versions of the gun. In the mid-1960s, Airmen guarding flight lines in Vietnam and South Korea, as well as bases in the United States, began receiving the shorter guns. By that point, Colt had taken over production of ArmaLite’s design and was selling them as the Colt Automatic Rifle-15, or CAR-15, family.

An airmen aims a GAU-5/A “submachine gun” during Operation Desert Shield. (Air Force)

The first of these shortened versions for the Air Force came with a 10.5 inch barrel and a massive flash hider that added another 4 inches to the overall length. With no naming convention for small arms, the service put the gun into the aircraft gun category Aeronautical and Support Equipment Type Designation System. This GAU-5/A became the standard issue weapon for Security Police dog handlers and other specialized personnel. The Army had bought a virtually identical version of the gun from Colt called the XM177E1. Like the M16 and M16A1, the only difference between it and the GAU-5/A was the addition of the forward assist. On paper, logisticians sometimes called the Air Force guns XM177s.

This dichotomy continued when both services started buying the newer guns with slightly longer 11.5” barrels. The Army designated its guns with the forward assist as the XM177E2, while the Air Force dubbed its model without the GAU-5A/A. All of the XM177s and GAU-5s were select fire models with semi- and full-automatic fire modes. The guns also came with early versions of the round hand guard seen on later M16-style guns.

The Air Force guns became most famously associated with the raid on the Son Tay prison camp in North Vietnam on Nov. 21, 1970. Nearly 60 Army Special Forces – some armed with GAU-5A/As specially fitted with the Armson Occluded Eye Gunsite, or OEG – along with more than 90 air force pilots and crew took part in the mission, also known as Operation Ivory Coast.

While the plan was to free American prisoners of war, the raiders found the North Vietnamese had moved the captives just prior to the operation. In 2016, Troy Defense announced the planned release of a limited edition semi-automatic clone of the raider carbine for the American civilian market to commemorate the event. Colt followed suit by announcing a similar, fully functional reproduction at the National Rifle Association’s annual meeting.

As defense spending shrank after the end of the Vietnam War, the Air Force had few reasons to spend valuable resources on new small arms. Still, combined with the introduction of the improved M16A2 rifle in the early 1980s, the service’s armories were becoming increasingly cluttered with an increasingly complicated mix of AR-15 pattern firearms. To help consolidate these weapons, the flying branch cooked up the GUU-5/P.

Air Force Combat Controllers with what looks like M4A1 carbines, but may just be another evolution in the GUU-5/P given the old-style stock (Air Force)

Despite the ostensible goal of standardization, these “submachine guns” can hardly be described as fitting a single standard. Over the years, Air Force armorers assembled them using older M16, M16A1, GAU-5/A and GAU-5A/A as the base. While the goal was a carbine with a 14.5-inch barrel and a collapsible stock, the specifications changed as time went on. Regardless of the exact features, only one National Stock Number – 1005-01-042-9820 – exists for GUU-5/Ps.

Initially, the Air Force simply replaced the existing barrels with a 14.5-inch lightweight or “pencil” type with a 1:12-inch rifling, according one Technical Sergeant at Lackland Air Force Base the author spoke with by phone nearly a decade ago. Retrofitted M16 or M16A1s would need new hand guards, barrel extensions, slip rings and butt stock assemblies.

The resulting weapon was akin to M16A1 carbines like the Colt Model 653 favored by U.S. special operations forces during the late 1970s and early 1980s. It is likely that some of the earliest examples were actually 653s straight from the Colt factory. Via FOIA, the author obtained a series of messages between individuals at Warner Robins discussing the potential to convert GUU-5/Ps rather than purchase new production guns. At the time, the unit cost for whatever this specific Colt model in question was, came to just over $550. Air Force officials estimated it would cost just under $315 to rebuild M16s to the same standard.

These early versions are sometimes referred to as GAU-5/Ps, though this seems to be a typo in some Air Force manuals that has entered the lexicon. The messages from the 24th Wing at Howard and from the personnel at Robins show the GUU-5/P nomenclature was well established by the mid-1980s. The scant official references to the GAU-5/P also use the same NSN as the GUU-5/P.

In addition, armorers would often strike the rollmarks on the lower receiver of converted guns with a series of stamped or eletro-penciled “Xs” and then add the new moniker. Sometimes the airmen would grind out the old markings entirely. While there are numerous examples of new GUU-5/P rollmarks, no photographs have surfaced of a GAU-5/P marking. The author obtained a copy of the 1989 version of the Air Force Technical Order for these firearms through FOIA, which shows the early conversion parts, including the pencil barrel. This document only lists GAU-5/A, GAU-5A/A and GUU-5/P.

As the 1:7-inch rifling became increasingly the default standard for 5.56mm weapons across the Pentagon, the Air Force stopped using the pencil barrels. The M16A2 had been the first to feature this tighter twist in order to stabilize the new, longer M856 tracer cartridge. In turn, GUU-5/Ps started getting 14.5-inch barrels with the same profile as these standard infantry rifles, making them similar to the Colt Model 727. After the introduction of the M4 in 1994, that weapon’s distinctive barrel with the cut for fitting the M203 grenade launcher became the default for Air Force conversions.

A civilian GUU-5/P clone built using parts from various sources. (Photo supplied to author)

All of these barrels were mated to the older upper receivers. So while the barrels were continually updated, the guns retained the older “A1” style rear sights that were adjustable for windage only. Converted GAU-5s carried over the two-position aluminum collapsible stocks coated with vinyl-acetate. Lower receivers could be slab-side without any of the later reinforcements above and around the magazine release. They might only have the partial “fence” found on earlier M16s and GAU-5s, too.

As the conversion program continued, the guns did begin to incorporate more and more features found on M16A2 rifles and M4 carbines. This included upper receivers with the newer rear sights with adjustable elevation, pistol grips with the additional finger grip and collapsible, composite material stocks. But the Technical Sergeant at Lackland made it clear that consistency was not as important as actually getting the weapons built to the basic carbine criteria.

How much the conversion process helped in consolidating Air Force weapons lockers is not entirely clear. By the early 2000s, Air Force instructions asking armorers to list what they had on hand, at various times, included slots for almost every member of the M16 rifle and M4 carbine family imaginable, as well as GAU-5s and GUU-5/Ps. As already mentioned, other documents mentioned issuing GUU-5/Ps only two years ago. At this time, most pictures show carbines with flat top style upper receivers with the integral Picatinny accessory rail and the Colt’s more recent reinforced, collapsible butt stocks. However, it is entirely possible some of these are merely the latest iteration of the conversions.

What is clear, is that the Air Force’s “mixmaster” carbines are a unique and interesting part of the Pentagon’s history with the Black Rifle. As new guns finally push the last of these weapons out of service, hopefully various examples of this particular chapter will find their way into museums where they belong.

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.

The Emerson Electric Company was founded in 1890 in St. Louis, Missouri as the Emerson Electric Manufacturing Company. The company initially produced electric motors and then went on to produce entire electricity powered machines like fans, sewing machines, and power tools. By the time the Second World War broke out, Emerson turned its already half century of experience with electric power into lucrative defense contracts.

One of the most notable products that Emerson made during the Second World War was power turrets for aircraft. The U.S. strategy of daylight aerial bombing raids over occupied Europe led to a demand for improved defensive armament for bomber aircraft. Emerson joined other companies like Bendix, Erco, Martin, and Sperry to produce powered turrets for various Allied bomber aircraft. Among these was the Emerson Model 250 bow turret, which was used by the U.S. Army Air Forces and the U.S. Navy on Consolidated B-24J and PBY aircraft respectively.

After the end of the Second World War, Emerson’s work with the U.S. military continued. By the end of the 1950s, Emerson had become one of the companies cooperating with U.S. Army efforts to develop armament subsystems for helicopters, a relatively new frontier at the time. One of the first standardized armament subsystems for U.S. Army helicopters, the M6 armament subsystem for the UH-1 series of helicopters, began with work Emerson started in 1958.

The first notable application of the TAT product line was the integration of the TAT-101 turret into Bell’s Model 207 Sioux Scout attack helicopter demonstrator. (U.S. Army Aviation Museum via Ray Wilhite)

The M6 was a fully powered weapon system, involving two sponsons mounted on each side of the aircraft, each mounting two 7.62mm M60C machine guns. The mounts could be elevated eleven degrees and depressed sixty-three degrees. The mounts could also be traversed inboard twelve degrees and outboard seventy degrees. A safety mechanism prevented the guns from traversing inboard enough to fire into the aircraft fuselage. This was all controlled from the co-pilot’s station, which was fitted with a flexible sighting system. The guns could also be locked in a forward position and fired by the pilot. Emerson later developed a variant of this subsystem, which also allowed for the carriage of 2.75-inch rocket pods. Further variants were developed from these, replacing the four M60C machine guns with two 7.62mm M134 “Miniguns.” The Minigun and rocket combination, which was designated the M21 armament subsystem, became one of the most popular armament combinations for UH-1 gunships during the conflict in Vietnam.

Emerson did not stop there, however. During the 1960s and 1970s, Emerson developed an entire line of powered turrets for aircraft, primarily helicopters. Emerson marketed these systems both to the U.S. military and overseas as part of the Tactical Armament Turret (TAT) line. Emerson’s in-house nomenclature designated these systems with the prefix TAT followed by a three digit number. The TAT family included aircraft turrets, as well as turrets for land vehicles and ships and other watercraft. Some turrets were marketed as being readily suitable for use in various environments.

Few products from Emerson’s TAT line met with significant success and many never progressed beyond the developmental stage, possibly never making it off the drafting table. While the TAT line was a major product offering, little information remains readily available about it. By the 1980s, Emerson had dropped the TAT nomenclature from its marketing literature. It is likely that any overview of the line is incomplete. For Emerson itself, an end to an era came in 1990 when the company completely divested its Government and Defense Group division. It was spun off to form the ESCO Electronics Corporation. Emerson no longer lists armament products on its website.

The Marine Corps purchased a total of ninety-four TAT-101E turrets for its UH-1Es. Seen here is one of these aircraft at the Bell factory. (National Museum of Naval Aviation via Ray Wilhite)

TAT Origins: The TAT-101, TAT-103 and TAT-111
The first product in Emerson’s TAT line was the TAT-101, a turret featuring two 7.62mm M60C machine guns. The turret’s power supply and five hundred round ammunition magazine were external to the turret. The turret was flexible, allowing for elevation, depression, and left and right traverse, which could all be controlled by using a flexible sighting system like the one developed for Emerson’s M6 armament subsystem. A number of subvariants were produced. For instance, Emerson offered the TAT-101D turret for the UH-1D helicopter. This particular turret had seventy three degrees of traverse left or right and the guns could be elevated fifteen degrees and depressed forty-five degrees. It is unclear whether all TAT-101 turrets had the same flexibility specifications or whether it varied depending on the aircraft to which the turret was fitted.

The first notable application of the TAT-101 came in 1963 after Bell Helicopter had been awarded a contract to produce a proof of concept attack helicopter demonstrator. The resulting aircraft, the Bell Model 207 Sioux Scout, took elements of Bell’s earlier Model 47G and 47J Sioux aircraft, but coupled with a completely new front fuselage. This new front gave the helicopter a look that is now common to most dedicated attack helicopters, with its two-man crew seated in tandem, one behind the other, and a with the Emerson turret in the chin position.

The U.S. Army decided not to pursue the Sioux Scout, but it did pave the way for future attack helicopter development. Emerson subsequently offered variants of the TAT-101 to the U.S. military for the UH-1 series of helicopters, marketing the TAT-101D to the U.S. Army and the TAT-101E to the Marine Corps for their UH-1E. In addition, given the larger main cabin of the UH-1D, Emerson also offered the option of a second flexible sighting system mounted on a sliding track attached to the cabin roof for individuals situated in the rear of the helicopter.

Emerson also offered the TAT-101D for the UH-1D, the general arrangement of which is outlined in this artwork. (National Air and Space Museum)

The U.S. Army did not procure the TAT-101D turret, but the U.S. Marine Corps did procure the TAT-101E. The Marine Corps purchased a total of ninety-four TAT-101Es, beginning to modify the UH-1E to carry them in April 1967. Aircraft fitted with the turret were used by helicopter units in Vietnam. Marine Corps experience with the turret in the Southeast Asian environment was not positive. The turret was found to be fragile and sensitive to environmental factors. Though delivered with a protective cover, Marine aircrews often dispensed with it due to the need to conduct frequent repairs. Instead, when the aircraft was on the ground, the turret assembly was wrapped in some manner of protective covering. By April 1972, the TAT-101Es had been removed from all aircraft.

Emerson also sought foreign sales for the TAT-101 series. The Federal Republic of Germany (FRG) evaluated a variant of the TAT-101D in the 1960s for its UH-1D aircraft. The turret for the FRG was designated as the TAT-103 and differed from the basic TAT-101 turret only in that 7.62mm MG1 machine guns were substituted for the M60s on turrets offered to the U.S. military. Emerson had already marketed the TAT-101 as being able to readily accept various major 7.62mm machine guns in use by the North Atlantic Treaty Alliance, including the MG1 and FN MAG. The FRG had no better an experience with the system and decided against procuring the system for its UH-1D fleet, canceling the program in August 1972.

In addition to the TAT-101 and TAT-103 turrets, Emerson developed a derivative of the turret with smaller ammunition magazines inside the turret itself. This was designated as the TAT-111. Emerson also marketed the TAT-101 for naval applications.

Minigun TATs: The TAT-102 and TAT-112
Emerson’s second TAT offering, the TAT-102, was similar in basic design to the TAT-101, but instead of having two machine guns it was designed specifically for the General Electric Minigun. Like the TAT-101, the turret’s power supply and ammunition magazine were external to the turret was flexible allowing for elevation, depression, and left and right traverse linked to a flexible sighting system. As the Minigun was electrically driven, by controlling the amount of power to the gun, the weapon’s rate of fire could also be controlled. In the TAT-102, the weapon could be set to fire at either two thousand or four thousand rounds per minute.

The TAT product line was not Emerson’s first foray into helicopter armament. Seen here is the left hand portion of the M6 (XM6E3) armament subsystem mounted on an HU-1B helicopter. (U.S. Army Aviation Museum via Ray Wilhite)

The TAT-102 was notably the first chin turret used on Bell’s AH-1G Cobra, continuing the close cooperation between Bell and Emerson in armed helicopters. The AH-1G was an outgrowth of Bell’s Model 209, a private venture to develop a purpose built attack helicopter. The Army initially procured the AH-1G in 1966 as an interim solution as delays continued to hound the Advanced Aerial Fire Support System (AAFSS) program. The prototype Model 209 and the initial production AH-1Gs featured the TAT-102 turret (sometimes also referred to as the TAT-102A), along with an eight thousand round magazine. The TAT-102 was only viewed as an interim system and was seen as being limited with its single gun. It was quickly replaced by the TAT-141 on the AH-1G.

In addition to being used on the AH-1G, the TAT-102 was also used on U.S. Air Force and U.S. Navy helicopters. The Navy’s HH-2C Seasprite, a specially configured version of the helicopter for the combat search and rescue, was initially fitted with a TAT-102 turret – the TAT-102K – in the chin position. The turret was mounted to the left of the aircraft centerline under the co-pilot’s position. Like the TAT-101, the TAT-102K had reliability issues, but also simply affected the aircraft’s center of gravity and added considerable weight. In many cases the turrets were removed from HH-2Cs and the turret was not a feature on the follow-on HH-2D.

Perhaps more interestingly, Emerson offered versions of the TAT-102 turret that were more like gun pods that could be carried on an aircraft’s stores stations like standard aircraft ordnance. The pod contained the TAT-102 turret and an eight thousand round magazine. The U.S. Air Force procured a limited number of TAT-102Bs for use on their CH-3E and HH-3E Jolly Green Giant aircraft, while the U.S. Navy procured a limited number of TAT-102Cs for use on their HH-3A Sea King aircraft. On the CH-3E and HH-3E, TAT-102Bs would be mounted in lieu of the jettisonable fuel tanks normally carried. On the HH-3A, a TAT-103C could be carried on the stores stations on either side of the aircraft, normally used on Navy SH-3A aircraft to carry torpedoes or depth charges. The guns were aimed using flexible sighting systems mounted in the main cabin of both types of aircraft.

Emerson developed all of the turrets for the abortive AH-56A Cheyenne attack helicopter, including the TAT-123 depicted in this artwork. The TAT-123 received the designation XM53. (U.S. Army Aviation Museum via Ray Wilhite)

The use of the TAT-102B and TAT-102C was limited for many of the same reasons as the TAT-102K on the HH-2C. The added weight reduced mission endurance and aircraft maneuverability. Air Force pilots were reportedly unhappy to have to choose between weapons and fuel on CSAR missions, where running out of fuel could place both the aircraft’s crew and any potential survivors in additional danger. Pintle mounted weapons at the crew doors and the rear ramp were more popular defensive armament on Air Force CH-3Es and HH-3Es and Navy HH-3As.

Also, as with the TAT-101, Emerson developed a derivative of the turret with smaller ammunition magazines inside the turret itself. This was designated as the TAT-112.

Arming the AH-56A: The TAT-123, TAT-124, and TAT-132
Though it developed turrets for use on the Bell AH-1 series of helicopters, Emerson also developed the turrets for the Lockheed AH-56A Cheyenne, the helicopter selected for the Army’s AAFSS program. The AH-56A helicopter was designed to feature two turrets, one in the chin, and one under the center of the fuselage, which could rotate along with the gunner’s seat – the XM112 swiveling gunner’s station. Sighting could also be achieved using the XM110 helmet mounted sight or the XM114 reflex sight in the pilot’s position. To provide additional flexibility, AH-56As could be fitted with one of two different chin turrets as well.

The two chin turrets were the TAT-123 and TAT-124. The major difference between the two was the weapon mounted. The TAT-123 contained a single XM196 machine gun, a variant of the basic M134 Minigun specifically designed for the installation that differed from the basic gun in that it lacked a rate limiter. The TAT-124 contained a single 40mm M129 automatic grenade launcher. The TAT-123 was coupled with a magazine containing over eleven thousand rounds. The TAT-124 on the other hand had a magazine with only seven hundred and eighty rounds. The TAT-123 and TAT-124 turrets received the designations XM53 and XM51 respectively. The TAT-132 belly turret contained a 30mm XM140 automatic cannon and fed from a magazine with a capacity of two thousand and ten rounds. The TAT-132 received the designation XM52.

The TAT-141 was the most successful product in the line, becoming the standard armament for the U.S. Army’s AH-1G, AH-1Q, AH-1S, and AH-1P helicopters. The TAT-141 received the designation M28. (U.S. Army Aviation Museum via Ray Wilhite)

Cannon Armed: The TAT-136 and TAT-140
Not to be dissuaded from a less than enthusiastic response to the TAT-102B, Emerson proposed additional methods of up-gunning U.S. Air Force HH-3Es in the late 1960s. The first of these proposals simply involved the fitting of a TAT-102 turret to the underside of the aircraft’s rear cargo ramp. In flight, the ramp would be lowered to make the turret level with the underside of the fuselage and from there it could provide three hundred and sixty degree coverage. The weapon would be controlled from one of four sighting stations or from a master control station in the cockpit.

At the same time, Emerson also proposed the fitting of two turrets at the front of the sponsons on the left and right side of the CH-53A aircraft, which the Air Force was investigating as a replacement for the HH-3E in the CSAR role. These turrets, the TAT-136, could be fitted with larger automatic cannon and installed in the sponsons would provide over one hundred and eighty degrees of coverage on either side of the aircraft. According to Emerson, the TAT-136, which was also offered as an armament option for the AH-1G, could accommodate a 20mm Mk 12 Mod 0 cannon, a 20mm M24 cannon, or a 30mm XM140 cannon. The U.S. Air Force decided against both the TAT-102 ramp arrangement and the TAT-136 for use on the HH-3E and the HH-53B/C aircraft.

The TAT-136 was also not selected for the AH-1G, after which Emerson developed another turret for the AH-1G, specifically designed to provide a “universal” mount for a wide variety of weapons. Only one weapon could be fitted at any one time, but Emerson marketed the turret as being able to accommodate most machine guns and cannon in the U.S. arsenal from 7.62mm to 30mm. The TAT-140 was evaluated by the U.S. Army, after being passed over initially, fitted with the XM140 cannon and designated as the XM120. In the end, both the U.S. Army and the U.S. Marine Corps selected the General Electric universal turret fitted with the 20mm M197 cannon for their up-gunned AH-1 aircraft.

Issues with the TAT-102B and TAT-102C did not dissuade Emerson from proposing a TAT-102 installation on the rear cargo ramp of the HH-3E to the U.S. Air Force. (National Air and Space Museum)

Arming the AH-1G: The TAT-141
In addition to the TAT-136 and TAT-140, Emerson also offered the TAT-141 as an option for additional firepower on the AH-1G. Unlike the TAT-136 and TAT-140, which were passed over, the TAT-141 became the standard armament for the AH-1G, receiving the designation M28. This turret was further refined and remained in use on the AH-1Q, AH-1S, and AH-1P Cobra helicopters, with the final variant being designated as the M28A3.

A significant improvement over the TAT-102, the TAT-141 allowed for the mounting of two M134 Miniguns, two M129 automatic grenade launchers, or one of each. The latter configuration became the most common. The weapons in the TAT-141 could be elevated twenty degrees and depressed fifty degrees, and the turret could be traversed one hundred and ten degrees to the left or right. The weapons fed from separate magazines, the type of which depended on which weapon was fitted in which position. Machine guns fed from four thousand round magazines, while grenade launchers fed from thirty round magazines.

M61A1 Turrets: The TAT-157 and TAT-161
Emerson’s TAT-157 and TAT-161 were both turrets for the General Electric M61A1 Vulcan cannon. There is some dispute about the turret nomenclatures, however. On 20 August 1968, the U.S. Air Force’s Air Staff directed Air Force Systems Command to mount an M61A1 cannon in place of the rotating bomb bay door on a B-57G Tropic Moon III aircraft as part of a project codenamed Pave Gat. This came after the demonstrated success of the M61A1 cannons mounted on the AC-130 gunship when attacking truck convoys. The gun would be linked to the onboard Low Light Level Television (LLLTV) and laser range finder on the Tropic Moon III aircraft.

Emerson also offered podded versions of the TAT-102, such as this TAT-102B, seen mounted on a U.S. Air Force HH-3E. (U.S. Air Force)

A weapons pallet that combined a turret developed by Emerson, an ammunition magazine, and power supply was fabricated in early 1969. The pallet arrangement, which replaced the aircraft’s bomb bay door, allowed the system to be rapidly mounted and demounted without major modification to the aircraft. Emerson documentation says that the turret system used for the Pave Gat program was the TAT-157. Air Force documentation says that it was the TAT-161. Emerson documentation acknowledges both turrets and it could be that they were functionally identical, but the TAT nomenclatures only refer to the specific type of aircraft on which the turret was to be fitted. Emerson documentation says that it proposed the TAT-161 as yet another possible armament option for the AH-1 series of helicopters.

Regardless of the appropriate nomenclature, Pave Gat continued into 1970. In addition to the weapon’s pallet, the aircraft’s AN/AQX-5 weapon delivery system was modified by Westinghouse to aim the gun. Westinghouse was also the primary contractor in the integration of the gun system. By April 1970, after a number of flight tests, the system was proven to be feasible. At that time, Westinghouse proposed the Air Force procure two Pave Gat systems for evaluation. The Air Force agreed and proposed one aircraft be tested at Eglin Air Force Base in Florida and another prototype system be deployed for operational evaluation at Ubon Royal Thai Air Base in Thailand.

The first aircraft arrived at Eglin Air Force Base in January 1971 and began conducting testing and evaluation. During these flights, the aircraft also tested a special type of flechette ammunition, which was also being developed under Pave Gat. The arrowhead-shaped flechettes, made of dense metal, were specifically designed to do maximum damage to soft-skinned vehicles that would be the aircraft’s primary target. Delays affected the Pave Gat program and in August 1971 it was decided as part of the U.S. drawdown in Southeast Asia to return the deployed B-57Gs in Thailand to the United States. Despite the functional nature of the Pave Gat system, it was decided that an operational evaluation of less than ninety days would be insufficient time to glean any useful information. In addition, the AC-130 gunship had fully proven itself already and the requirement for a second system to fill a similar role was reduced. On 21 December 1971, the Pave Gat program was terminated.

The second member of the TAT product line was the TAT-102, which featured a single Minigun. This TAT-102 is mounted on an early AH-1G. (U.S. Army Aviation Museum via Ray Wilhite)

TAT Cousins: The Mini-TAT and TAP-239
As mentioned, the Emerson TAT line gradually faded from view in the 1970s. Still, Emerson did market a small turret system for a period as the Mini-TAT. This system was designed to be mounted on almost any helicopter and was armed with a Minigun. The weapon was mounted so that while on the ground it would be folded under the aircraft in a stowed position. Once in flight, the weapon would be lowered and have a full three-hundred and sixty degrees of rotation below the helicopter.

The U.S. Army explored the Mini-TAT as part of the Modem Army Selected Systems Test, Evaluation and Review (MASSTER) as a possible weapon for scout helicopters. The system was also evaluated by the Canadians, who loaned some to the U.S. Air Force as part of the Joint Countering Attack Helicopters (J-CATCH) program, which sought to develop tactics to counter Soviet attack helicopters such as the Mi-24 Hind. Though it was not procured by the U.S. or the Canadians, Emerson continued to market the Mini-TAT. At least one sale was made to Oman, who mounted the system on Bell 206 helicopters. Emerson continued to offer the system into the 1980s, but having dispensed with the TAT nomenclature, relabeled the system as the Flexible Turret System (FTS).

Emerson also produced at least one traditional gun pod called the TAP-239, with TAP standing for Tactical Armament Pod. The TAP-239 contained a single 20mm M39 cannon, and was marketed again primarily for the AH-1 series of helicopters, though it could be mounted on any aircraft with the appropriate mounting hardware.