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Plastic Shot: Atypical Ammo

Polymer cartridges are a technology in which the US military has invested for more than 60 years. She spawned some of the craziest experimental ammunition in the history of weapons and some of the most promising.

How were the U-shaped, flat and triangular cartridges arranged? Why are some seemingly obvious engineering solutions unable to be implemented for more than half a century? The answers to these questions, photographs and drawings of the once secret military developments - under the cut.

The era of all-metal ammunition for small arms is drawing to a close.
« . , », — Comparison of Folded and Telescoped Ammunition, Hoppmann Corporation

A fair remark, this is just a quote from a report prepared for the Springfield Arsenal in 1975. Since then, a lot of water has flowed. Weapons began to be printed on 3D printers, and the military still uses ammunition from the early 20th century. But, before I delve into the history of the issue and talk about the reasons for such a delay in the development of small arms - a warning.

I took into account the criticism of the previous article , so this text turned out to be really long, but, thanks to this, quite complete. If the short format is closer to you, keep in mind that I regularly share weapon finds on the GunFreak Telegram channel .

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Triangular Ammo by David Dardic


The first attempt to rethink the modern configuration of the cartridge using a plastic sleeve was the system developed by David Dardick, a friend of Melvin Johnson, the inventor of the semi-automatic rifle, competing with the M1 Garand.
Dardik began developing a new cartridge and weapons for him a year before the release of Johnson M1941 , but he received a patent for open chamber gun only in September 1954.


I mentioned the revolver of the Dardik design in another post . This time we focus on the cartridge and the professional path of the designer

The revolver was intended for shooting triangular round - tround-rounds, where the bullet is deeply planted in a plastic sleeve of complex shape. According to the designer, such an ammunition was supposed to help combine the advantages of a pistol and a revolver in one weapon: large ammunition and simplicity of design.

Indeed, the Dardica revolver could have an integral store for 11, 15 or even 20 shots, and the principle of its operation can be described in a couple of sentences.

Ammunition was delivered from the store to a special drum. Its chambers were bored and devoid of the outer wall, its role was played by the cartridge case. After pulling the trigger, the drum rotated a third of a turn, and the revolver fired.

Confident of success, the designer in 1958 opened the Dardick Corporation and revolvers under the tround-cartridge hit the civilian market.


David Dardic (right) demonstrates his designs to Melvin Johnson.

Despite an active advertising campaign, this weapon did not have any noticeable success. Probably, the optimism of Dardik was not justified due to the high price of ammunition. In 1960, the Dardik revolvers were discontinued. According to various estimates, from 50 to 100 units were manufactured. The remaining parts were sold to Numrich Arms Corporation, which still sells parts for these weapons.

Despite the commercial failure, tround cartridges had the following advantages:

  • . . , , .
  • - «» Tround-, .
  • . 2 . — , .

The last two points, most likely, interested military suppliers. In 1962, Harrington & Richardson (H&R) contacted Dardic . They needed help creating an assault rifle to compete in the SPIW Special Purpose Individual Weapon army competition .



The H&R SPIW prototype was ready in March 1964. Its design combined translucent plastic and steel, but conceptually the internal device of the H&R SPIW echoed the Dardic revolver.

The gas piston was the only part of the rifle, which made a reciprocating movement and at the same time covered a considerable distance. The piston set in motion a drum with three open chambers.



For one cycle of automation, the drum rotated a third of a turn, picked up the cartridge supplied from the magazine, moved it to the barrel line and at the same time threw out the fired cartridge case. She hung on a flexible plastic tape holding together 20 cartridges that were placed in a drum magazine.

Inspired by the prospects of sagittal sub-caliber bullets, American designers packed three sub-caliber metal arrows from XM144 cartridges into a "triangular" 5.6x57 mm sleeve . When the cartridge fell into a fighting position, all three arrows were opposite three smooth channels drilled in the H&R SPIW barrel. Thus, in one shot, the rifle fired three high-speed steel darts at once.

At the time of testing, Harrington & Richardson already had a bad reputation due to the poor quality of its M1 and M14 rifles, and the unsuccessful alteration of the FN FAL for another such competition. The Dardic prototype only confirmed this reputation.

On paper, the H&R SPIW design looked promising, but tests revealed fundamental problems.

One of them is due to the fact that during the shot all three channels of the barrel communicated through the volume of the sleeve where the burnt gunpowder was placed. The first dart that flew out caused a sharp drop in pressure in the two remaining bore channels. In the best case, this led to a decrease in muzzle velocity and, accordingly, the range and accuracy of the other two bullets. At worst, the shooters could not leave the barrel at all and prevent the next shot.

Another problem was the insecurity of the open-cam drum. All that protected the shooter from breakthrough of powder gases in the case of H&R SPIW was a thin wall of a plastic sleeve. During the tests, it was noted how often it was deformed. If the cartridge had been damaged or defective, the shooter would not have been too good.


Various tround-cartridges: 38 Dardick (three options); 5.6 mm Triplex; .30 HIVAP; .310 Rock Drilling with ceramic bullets; .50 Dardick

However, to remove the rifle from the tests, it was enough that it weighed 23.9 pounds (more than 10 kg), while in the competition rules they limited the weight of special weapons to 10 pounds (4.5 kg).

It could be said that the failure with the H&R SPIW put an end to tround cartridges, but the enterprising designer continued his research.


In 1967-1970, they became interested in tround cartridges in the weapons division of TRW Corporation. They constructed an HIVAP machine gun under tround cartridges with a 7.87 mm sub-caliber bullet. And although I could not find direct evidence of this, most likely, Dardik advised the company's engineers. In the project, the hand of the master is felt.

HIVAP had an electric drive, eight trigger mechanisms and as many smooth trunks that fired in pairs with a rate of 30 thousand rounds per minute.


The Pentagon commission that was tested was impressed, but then multiplied the rate of fire by the cost of the cartridge and prudently refused the machine gun.

In 1970, Dardik conceived a gun under a "triangular" projectilebut in the end there was peaceful use for his patrons. They became part of the 1977 patented deviated oil well drilling system.

In the Terra-Drill, “triangular” cartridges were used to destroy sections of the rock through which the drill would not otherwise have passed, deviating from the correct path. This time, the plastic sleeve was equipped with ceramic bullets that did not reach the target at the same time, but with a short delay, creating numerous shock waves that destroyed the rock.

It was in this form that the tround cartridges brought real benefits and provided David Dardic with recognition, but he did not calm down, and continued to invent strange weapons.

For example, in 1988, Dardik patented another, four-barreled machine gunfiring three darts at a time. He remained on paper.

Lockless chuck


The next variety of polymer cartridges was invented in 1967 by designer Morris Goldin, an employee of the helicopter company Hughes Helicopters . For their distant resemblance to pads of popular chewing gum, contemporaries nicknamed them chiclets, but in the documents this ammunition appears under the name lockless.

Lockless-cartridge was a hollow plastic box, divided by partitions into three parts. The bullet was placed in the middle, while the bulk of the powder was poured into the side chambers.

To make the cartridge more compact, Goldin used phased ignition. First, the capsule ignited a small amount of explosive. It was enough for the bullet to move, plug the hole in the front of the plastic sleeve and seal it. When the bullet moved, openings leading to the side chambers opened, and the main volume of the powder ignited, enough to push the bullet out of the barrel.

The result is a very tight layout. Lockless were significantly lighter than conventional cartridges of the same caliber and took up 54% less space.

By order of the famous gunsmith James Sullivan (James Sullivan) Maurice Goldin designed a prototype weapons for a new cartridge. He charged from the side, through one of the two windows in the receiver. Each subsequent cartridge simply squeezed the previous one out of the chamber, and a sliding sleeve covered the holes before firing.

The military learned about lockless cartridges only in 1986-1988. By this time, McDonnell Douglas Helicopter had separated from the Hughes Helicopters , which signed a contract with Picatinny Arsenal and agreed to participate in the next program for the development of weapons of the future - Advanced Combat Rifle (ACR).



Goldin's patents formed the basis of an improved rifle, which had a store for ten rectangular rounds. But only at McDonnell, it seems, they considered the cartridge not revolutionary enough and began to make changes to the drawings that the designer had thought through from the late sixties.



From the surviving ACR program documents, it is clear that McDonnell Douglas engineers first tried to fit two or three bullets into the lockless cartridge, and then tried several different types of darts until they settled on three .338 (8.6 mm) caliber cartridge.



It was with such ammunition that in May 1988 the prototype was put to the test, and by June McDonnell Douglas had left the competition ahead of schedule in connection with the hardware immaturity of its rifle. Darts from hastily remade ammunition simply flew past the target.

Folded cartridge


Perhaps the most unusual cartridges of the mid-20th century were the "folded", folded-cartridges of Andrew J Grandy (Andrew J Grandy). This designer, who had worked at Frankford Arsenal since 1969 , believed that the future lay in U-shaped cartridges with a powder chamber located separately, on the side of the bullet. And, strangely enough, the management of the arsenal supported him.

According to Grandi's drawings, an experienced 5.56 mm cartridge was manufactured under the name FABRL - Frankford Arsenal Ballistic Research Laboratory.



Grandi planned to make it metal, but the welded metal sleeve did not work well and was replaced with a plastic one made by rotational injection molding.

The strange shape of the cartridge was supposed to reduce the erosive effect of powder gases on the bore and reduce the course of the moving parts of automatic weapons, which means to increase the rate of fire and reduce the load on the mechanics.

Interestingly, for the development of FABRL, computer simulation was used - one of the first applications of the finite element method for the design of small arms. On what exactly the calculations were made, it is not clear from the documents, but, according to rough estimates, in the 70s such calculations would require the capacities of the latest mainframe.

For tests of “folded” cartridges, two rifles were remade: the American M16A1 and the Belgian FAL.

The surviving images of these rifles are not encouraging detail. All because they are takenfrom an electronic copy of a paper copy of the microfiche of the test report .

In tests, the FABRL cartridge showed results comparable to the standard NATO 5.56x45 cartridge, but, again, was lighter, shorter and generally more compact. It was possible to pack 29% more "folded" cartridges than ordinary ones into the same zinc or box. However, the advantages faded in comparison with the costs of production and the problems caused by the asymmetric form.

In order for a regular round cartridge to get into the chamber, in general, it’s enough to forward it with a bullet. For a folded cartridge, it is crucial that it is fed in the correct orientation. A deviation of a couple of degrees is enough, and the camera for gunpowder will not take its place.

After testing, collecting and analyzing data, the researchers concluded that the FABRL cartridge is not suitable for the needs of the US Army. Research decided to collapse. In addition, by the mid-70s, it became clear that the Frankfurt arsenal was losing in competition to new, more modern plants.


Andrew Grundy, around the 1970s,

Grundy apparently understood what was going on. By the end of 1974, he patented his cartridge and, shortly before the official closure of the arsenal, founded his own company Grand Technologies Group.

Until 1983, the designer, on his own initiative, designed and tested folded cartridges of various calibers: 4.32 mm, 5.56 mm, 7.62 mm, 12.7 mm and 30 mm. He even designed a three-bullet variant, vaguely reminiscent of Dardic's triplex cartridge.



As you might imagine, nobody was interested in the technology of folded cartridges. Soon they turned into the coveted dream of any ammunition collector.

Smart Weapons and Overloaded Soldiers


In the 80s of the last century, the development of polymer munitions in the United States came to a standstill and, after the completion of the Advanced Combat Rifle program in 1990, stopped for a decade. The new fix idea for the military was the Objective Individual Combat Weapon , a project to create an XM29 automatic grenade launcher system with a smart computerized sight.

They spent more than $ 100 million on it, but even the simplified and improved version - the XM25 grenade launcher - turned out to be too heavy. During trials in Afghanistan, the US military simply refused to take these bulky weapons to sorties. In 2014, the program was closed.


XM25 "smart" grenade launcher in the hands of an American soldier

The polymer cartridges were again remembered in 2003, after numerous reports had arrived at the command about how much equipment the American private was forced to carry. The following year, the Lightweight Machine Gun and Ammunition initiative was launched and it started again ...

Textron and True Velocity


Not so much is known about modern developments of polymer cartridges as about projects a century and a half ago. What is clear is that in the United States two initiatives emerged from the hell of a production. Textron's



CT polymer cartridges combine the ideas of David Dardik and Maurice Goldin. Thanks to the use of bullets from the standard 5.56 mm NATO cartridges, entirely placed in a plastic sleeve, they resemble a tround cartridge. With Lockless cartridges, the reloading scheme is related by a novelty, where the new cartridge simply pushes the cartridge case remaining from the previous one. For the LSAT machine gun and the Textron NGSW family of weapons, witty automation has been designed where the chamber is tilted to the side to reload.




Automation scheme for Textron CT cartridges on the example of the machine gun of the same name. Caution, sound!

Polymer cartridge project from True Velocity Inc. not so revolutionary. Quite the contrary. It is so conservative that it may seem strange why something like this has not been done before.



Most likely, before it was not possible to pick up material with suitable properties, but now the military is offered ammunition with polymer sleeves, similar in shape to brass counterparts.

The only compromise that the designers of Velocity Inc. had to make was - a metal base with a rim that allows you to remove the sleeve "the old fashioned way", using the clinging to the protrusion of the extractor. But, with such cartridges you don’t have to reinvent the rifles and machine guns, and this is a significant competitive advantage.


It is difficult to say how soon LSAT, True Velocity or similar developments will go into service. And it's not that these cartridges are bad or not well tested.


General Dynamics RM277 assault rifle chambered for True Velocity cartridge

From the very beginning of research, back in the 50s, it became clear that polymer cartridges, regardless of design, provide significant savings in weight, not to mention metal. Modern polymers withstand higher pressure than brass sleeves. Due to the lower thermal conductivity, they reduce the likelihood of self-ignition of the cartridge when the weapon overheats. In addition, they combine well with electric ignition systems. But, when it comes to the introduction of polymer cartridges, the estimated costs and potential risks stifle the initiative in the bud.

To adopt a new cartridge is to shake up the entire military machine to the base: reorganize production, massively replace weapons, retrain soldiers, rebuild logistics. To launch such a project, it is necessary to overcome the colossal inertia. And the larger the army, the stronger it is.


One of the prototypes of the LSAT machine gun chambered for Textron CT.

In addition, at the time of the introduction of the new polymer cartridge, the question inevitably arises of choosing the caliber of ammunition that is most suitable for mass use in war conditions. This is a separate sore point, requiring lengthy research and, no less, a review of military doctrine throughout the whole country.

Therefore, in developed countries, new cartridges are adopted very rarely, about once every 50 years. It is unlikely that the future will be for traditional ammunition in brass shells, but if by the end of the 21st century they will continue to form the basis of armaments in most countries of the world, and polymer ammunition can only be seen at experimental ranges, but in the hands of collectors, this will not be nothing surprising.

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