Special Purpose Individual Weapon - AbsoluteAstronomy.com

The Special Purpose Individual Weapon (SPIW) was a long-running United States Army

United States Army

The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

program to develop, in part, a workable flechette

Flechette

A flechette is a pointed steel projectile, with a vaned tail for stable flight. The name comes from French , "little arrow" or "dart", and sometimes retains the acute accent in English: fléchette.-Bulk and artillery use:...

-based "rifle", though other concepts were also involved. The concepts continued to be tested under the Future Rifle Program and again in the 1980s and 1990s under the Advanced Combat Rifle

Advanced Combat Rifle

The Advanced Combat Rifle was a United States Army program to find a replacement for the M16 assault rifle. The program's total cost is approximately US$300 million...

program, but neither program resulted in a system useful enough to warrant replacing the current M16.

Project SALVO

The idea of a flechette

Flechette

-based individual weapon started in earnest during the Army's Project SALVO. SALVO had earlier concluded that a small weapon with a high rate of fire would be considerably deadlier than the large "full power" weapons being developed in the 1950s, and followed several lines of investigation to find the best way to provide high firing rates. SALVO had a small number of "duplex load" weapons developed, where two bullets were stacked, while Springfield Armory and Olin/Winchester both entered multiple barrel firearms.

Even before the SALVO tests, Irwin Barr of AAI Corporation

AAI Corporation

AAI Corporation is an aerospace and defense development and manufacturing firm in Hunt Valley, Maryland, USA. It is formerly a wholly owned subsidiary of United Industrial Corporation, AAI was acquired by Textron in 2007 and currently is an operating unit of Textron Systems Corporation...

had been developing single and multiple flechette cartridges. The Navy became sufficiently interested in the concept to provide him with some development funding from the Office of Naval Research

Office of Naval Research

The Office of Naval Research , headquartered in Arlington, Virginia , is the office within the United States Department of the Navy that coordinates, executes, and promotes the science and technology programs of the U.S...

, resulting in a 12 gauge shotgun shell firing 32 flechettes. The Army later added funding as well, and AAI was invited to SALVO. In SALVO testing they were found to be able to penetrate one side of a standard steel helmet at 500 yards (460 m)—excellent given their light weight—but the dispersion of the darts was so great as to make them only marginally useful.

Further development continued by adapting a Winchester Model 70

Winchester Model 70

The Winchester Model 70 is a bolt action sporting rifle. It has an iconic place in American sporting culture and has been held in high regard by shooters since it was introduced in 1936, earning the moniker "The Rifleman's Rifle". The action has some design similarities to Mauser designs and it is...

rifle with new XM110 5.6×53 mm rounds firing a single dart. The result was a weapon with somewhat less accuracy than the 7.62x51mm NATO rounds, but with equal penetration and a trajectory so flat it could be fired with no sights out to 400 yards (370 m). Better yet the rounds were very light, and had almost no recoil in comparison to even the 0.22-inch caliber weapons under development. This meant they could be fired at extremely high rates of fire, from a very lightweight weapon.

Since the Army was by this time only interested in fully automatic weapons, Barr suggested that they build a multiple barrel prototype in order to quickly test the concept. Various multiple barrel rifles entered the project. The resulting "burst simulators" were tested in 1961, and the general conclusion was that the light weight of the flechette meant that it could be fired at extremely high rates of fire, the baseline being 2300 rpm, from a weapon of only 3.5 pounds (1.6 kg), fully loaded with 60 rounds. Accordingly, the Army became extremely interested in the weapon.

Project NIBLICK

Meanwhile the Army's Operations Research Office

Operations Research Office

The Operations Research Office was a civilian military research center founded in 1948 by the United States Army. It was run under contract by Johns Hopkins University. The organization's offices were originally at Fort McNair, Washington, D.C. They moved to Chevy Chase, Maryland in 1952...

, ORO, had been working on Project NIBLICK, follow-on to SALVO to develop a modern grenade launcher

Grenade launcher

A grenade launcher or grenade discharger is a weapon that launches a grenade with more accuracy, higher velocity, and to greater distances than a soldier could throw it by hand....

. Interested in the original shotgun-type shells, they recommended development of a dedicated flechette-firing weapon combined with a grenade launcher, the SPIW. The final requirements resulted in an over-under weapon, firing flechettes from one barrel, and grenades from the other. It was to weigh under 10 pounds (4.5 kg) fully loaded with three grenades and 60 flechettes.

Four companies responded to the contract tender: AAI, Springfield Armory

Springfield Armory

The Springfield Armory, located in the City of Springfield, Massachusetts - from 1777 until its closing in 1968 - was the primary center for the manufacture of U.S. military firearms. After its controversial closing during the Vietnam War, the Springfield Armory was declared Western Massachusetts'...

, Winchester Arms and Harrington & Richardson. AAI continued with the original 5.6x53 mm XM110 rounds, while Springfield and Winchester used a new 5.6×44 mm XM144 cartridge. The H&R design loaded the dart from the XM144 into their own cartridge design.

The H&R design was the most advanced. It mounted the dart between three plastic sabots in a triangular plastic cartridge. When fired, the sabots were discarded early in small "sub-barrels" while the dart continued down the main barrel. Although the rounds were lightweight the weapon itself was not, at 24 pounds (11 kg) loaded, and the weapon was quickly eliminated from the contest.

Winchester's design used a "soft recoil" stock which absorbed the recoil of an individual round in a spring. The idea was to allow three rounds to be fired before the spring was completely compressed, meaning that there was very little recoil until the end of the burst. This was intended to dramatically increase the accuracy of burst fire, but the system never truly worked, and was later dropped. The grenade launcher portion of the design proved much more interesting, however, and work continued on that portion.

The Springfield entry was most interesting for its layout. It used two 30-round magazines back-to-back in a bullpup layout

Bullpup

Bullpups are firearm configurations in which the action is located behind the trigger group and alongside the shooter's face, so there is no wasted space for the buttstock as in conventional designs. This permits a shorter firearm length for the same barrel length for improved maneuverability, and...

, taking rounds from the front magazine first. However, their massive magazine-fed grenade launcher pushed the weight to 14 pounds (6.4 kg), and it seemed unlikely this could be reduced by much.

Oddly, AAI's design was the least technically advanced. The flechette gun portion was somewhat heavy, but fired at 2400 rpm. Their grenade launcher was a simple single-shot weapon; their semi-automatic version was not ready in time for testing.

The conclusion of the testing was that none of the weapons were ready for development into a combat system. The AAI flechette portion and the Winchester grenade launcher were both interesting for general development, however. More worrying was the result of general testing of the flechette concept. While the weapons delivered on their promise of extremely high rates of fire and excellent penetration, the rounds themselves were extremely expensive to produce, and the darts could be easily deflected in flight even by heavy rain. Finally, the rounds gave off extremely loud reports and had a huge muzzle flash, making the guns easily visible in low light.

A second round of testing followed, with the Springfield model adopting the Winchester grenade launcher with a disposable magazine and a new side-by-side layout for the flechette magazines. AAI's design was equipped with their semi-automatic launcher, which was now complete, and a new plastic buttstock/sighting system. Neither updated version proved very reliable and both were over the 10 pound (4.5 kg) limit. In 1966 SPIW was put into "maintenance mode" and the M16 adopted.

AAI continued development at a low level, and eventually managed to dramatically improve the reliability of their XM19. However, this revealed another problem: heat buildup in the chamber was great enough to result in "cook off

Cooking off

Cooking off refers to ammunition exploding prematurely due to heat in the surrounding environment. It can also refer to a technique used when throwing grenades to achieve a controlled, predictable explosion....

". Changes in the Army command structure and the adoption of the M16 made interest in the SPIW fade, and eventually the project was allowed to die. Ironically, AAI's original "simple" grenade launcher turned out to be a major success: it was selected as the M203

M203 grenade launcher

The M203 is a single shot 40 mm grenade launcher designed to attach to a rifle. It uses the same rounds as the older M79 break-action grenade launcher, which utilize the High-Low Propulsion System to keep recoil forces low. Though versatile, and compatible with many rifle models, the M203 was...

in 1968 and became a common weapon under the M16.

The Future Rifle Program

In 1969, the Army started the Future Rifle Program, and invited AAI

AAI

-Organizations:* AAI Corporation, a United States company* Adam Aircraft Industries, a United States company* Aiesec Alumni International, a global association of former volunteer members, executive boards, international trainees or Staff of AIESEC...

to enter against General Electric

General Electric

General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...

's Dual Cycle Rifle

Dual Cycle Rifle

The Dual Cycle Rifle was a 5.56x45mm NATO calibre revolver-type assault rifle that used a unique gas operation with a Webley-Fosbery-type grooved cylinder enabling 3-round bursts capable of firing 4,900 rounds per minute.-Overview:...

, a derivative of the Springfield SALVO design. (Springfield had closed in 1968.) Additional entries with multiple flechettes or bullets ("micro-caliber") were also entered, mirroring the original SALVO tests of the 1950s. However, the program came under attack by the United States Congress

United States Congress

The United States Congress is the bicameral legislature of the federal government of the United States, consisting of the Senate and the House of Representatives. The Congress meets in the United States Capitol in Washington, D.C....

as a waste of money, and was forced to scale back. Testing finally began in 1974. The AAI design never managed to fire more than six bursts before jamming. A possible entrant was the French designed VFIW assault rifle

Volley Firing Infantry Weapon

The Volley Firing Infantry Weapon was a rifle concept of French origin designed by Pierre Jampy. The weapon was gas operated, and was fed by clips holding 3 rounds. The VFIW had the capability of firing on both semi and full automatic and adjustable spread....

Close-Assault Weapon System (CAWS)

It was revived again during the semi-automatic shotgun-like Close-Assault Weapon System (CAWS) project in the early 1980s. A number of designs were entered and offered fairly good reliability, but the entire concept of a large weapon for use out to 100 yards was questioned and the project later dropped.

Advanced Combat Rifle (ACR)

The concept was revived yet again during the Advanced Combat Rifle

Advanced Combat Rifle

The Advanced Combat Rifle was a United States Army program to find a replacement for the M16 assault rifle. The program's total cost is approximately US$300 million...

(ACR) trials in the early 1990s. Several designs were entered, from the simple Colt ACR

Colt ACR

The Colt ACR was Colt's entry in the U.S. DoD Advanced Combat Rifle program, which concluded with the result that none of the entrants achieved enough of an improvement over the M16 to be worth the cost....

to the more interesting flechette designs, such as the Steyr ACR

Steyr ACR

The Steyr ACR was a prototype flechette-firing assault rifle built for the US Army's Advanced Combat Rifle program of 1989/90. Although the Steyr design proved effective, as did most of the weapons submitted, the entire ACR program ended with none of the entrants achieving performance 100% better...

. Although the basic problem of a single-dart flechette round had finally been solved by this time, none of the weapons entered offered the 100% improvement over the M16 that the Army tests required.

Modern variants

Since the demise of the SPIW, there has been another attempt to revolutionize the assault rifle

Assault rifle

An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...

by way of a small projectile and a very high rate of fire, namely the West German

West Germany

West Germany is the common English, but not official, name for the Federal Republic of Germany or FRG in the period between its creation in May 1949 to German reunification on 3 October 1990....

Heckler & Koch G11

The Heckler & Koch G11 is a non-production prototype assault rifle developed during the late 1960s, 1970s and 1980s by Gesellschaft für Hülsenlose Gewehrsysteme , a conglomeration of companies headed by firearm manufacturer Heckler & Koch , Dynamit Nobel The Heckler & Koch G11 is a non-production...

caseless rifle. That project did not result in a production rifle either, as the reunification of Germany

German reunification

German reunification was the process in 1990 in which the German Democratic Republic joined the Federal Republic of Germany , and when Berlin reunited into a single city, as provided by its then Grundgesetz constitution Article 23. The start of this process is commonly referred by Germans as die...

put financial strains on the German Army budget, which caused the project to be dropped. A similar project by LSAT

Lightweight Small Arms Technologies

The Lightweight Small Arms Technologies program is funded by the U.S. Joint Service Small Arms Program, with the goal of significantly reducing the weight of small arms and their ammunition...