3D Printing

Sintercore creates first commercial 3D printed metallic firearm component

Sintercore creates first comme...
An AR-15 pistol equipped with an Auxetic muzzle break (Photo: Sintercore)
An AR-15 pistol equipped with an Auxetic muzzle break (Photo: Sintercore)
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An AR-15 pistol equipped with an Auxetic muzzle break (Photo: Sintercore)
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An AR-15 pistol equipped with an Auxetic muzzle break (Photo: Sintercore)
Side view of an Auxetic-equipped AR-15 pistol being fired (Photo: Sintercore)
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Side view of an Auxetic-equipped AR-15 pistol being fired (Photo: Sintercore)
Colt AR-15 Sporter SP1 Carbine has a 16.1 inch barrel to satisfy US ATF regulations
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Colt AR-15 Sporter SP1 Carbine has a 16.1 inch barrel to satisfy US ATF regulations
Olympic Arms K23 AR-15 pistol with a 6.5 inch barrel equipped with a sight and a flash suppressor. The tube extending from the back of the pistol is the receiver extension, within which the bolt of the firearm's action travels back and forth (Photo: Steven Z via Wikimedia Commons)
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Olympic Arms K23 AR-15 pistol with a 6.5 inch barrel equipped with a sight and a flash suppressor. The tube extending from the back of the pistol is the receiver extension, within which the bolt of the firearm's action travels back and forth (Photo: Steven Z via Wikimedia Commons)
Sintercore's Auxetic Inconel muzzle break. The central image is a target's eye view of the device, and the other images are rotations from that position (Photo: Sintercore)
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Sintercore's Auxetic Inconel muzzle break. The central image is a target's eye view of the device, and the other images are rotations from that position (Photo: Sintercore)
Schematic of how Direct Metal Laser Sintering works (Photo: Materialgeeza via Wikimedia Commons)
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Schematic of how Direct Metal Laser Sintering works (Photo: Materialgeeza via Wikimedia Commons)

Michigan-based Sintercore is billing its Auxetik (pronounced Aug-ZETIK) as the first commercial 3D printed firearm muzzle brake. Made of Inconel alloy using a laser additive manufacturing process, the Auxetik is designed to tame the recoil and muzzle rise of AR-15 pistols chambered for .223 caliber (5.56x45mm) NATO rounds.

The AR-15 is the semi-automatic civilian version of the military M-16, which is used by over 80 countries. While the AR-15 is used for target shooting and hunting, it also occupies an unusual position in the gun world by account of its modular design that allows for extensive customization.

Olympic Arms K23 AR-15 pistol with a 6.5 inch barrel equipped with a sight and a flash suppressor. The tube extending from the back of the pistol is the receiver extension, within which the bolt of the firearm's action travels back and forth (Photo: Steven Z via Wikimedia Commons)
Olympic Arms K23 AR-15 pistol with a 6.5 inch barrel equipped with a sight and a flash suppressor. The tube extending from the back of the pistol is the receiver extension, within which the bolt of the firearm's action travels back and forth (Photo: Steven Z via Wikimedia Commons)

When the stock of an AR-15 is removed and there is only one grip, it is considered under US ATF (Alcohol, Tobacco, and Firearms) regulations to be a pistol. This allows it to be used with a short barrel, typically in the 6 to 12 inch range, whereas as a rifle the barrel must be longer than 16 inches to avoid special licensing requirements.

The AR-15 pistol modification does not result in the most practical firearm. Such a pistol has stronger recoil and muzzle flip than do the rifle versions, as you might expect from a lighter gun, the backward shift in the center of mass of the gun and the loss of stabilization from the stock. Adding a muzzle brake to direct the propellant gases emerging from the barrel upwards and backwards help to minimize these effects, and make the pistol more controllable.

Sintercore has developed a new muzzle brake design for exactly this purpose – taming the AR-15 pistol. Its muzzle brake includes design elements that would be difficult and expensive to create using conventional machining methods, including being fabricated from an Inconel alloy, so it has chosen to use 3D printing via the Direct Metal Laser Sintering (DMLS) process.

DMLS is a bit of a misnomer, as the process does not involve sintering. Sintering is a process in which a powder is consolidated by using heat and pressure to activate atomic diffusion near the particle surfaces to join the particles together into a mass. This mass, however, typically still contains voids, and the grain boundaries between particles tend to be relatively weak.

Schematic of how Direct Metal Laser Sintering works (Photo: Materialgeeza via Wikimedia Commons)
Schematic of how Direct Metal Laser Sintering works (Photo: Materialgeeza via Wikimedia Commons)

In contrast, in the DMLS process, an object being "grown" is covered with a very thin layer of metal power, which is then scanned by a laser so it melts, along with a thin layer of the underlying growth surface, thereby forming a full density solid object.

DMLS is capable of great accuracy, with thickness of the growth layers being as small as 20 microns (0.0008 inch), and tolerances perpendicular to the growth direction of about 100 microns (0.004 inch). It is a slow process at present, adding about 2 cubic millimeters per second (about 7 cc/hr) when growing an object of Inconel alloy, but this may improve with additional developmental work.

Using this process,the Inconel has about 70 percent of the strength of properly heat-treated Inconel. The lower strength is caused by the rapid solidification of the alloy after the laser passes over. Once the DMLS Inconel parts are subjected to a standard heat-treatment, they display strength and ductility nearly identical to a more conventionally machined component.

Sintercore's Auxetic Inconel muzzle break. The central image is a target's eye view of the device, and the other images are rotations from that position (Photo: Sintercore)
Sintercore's Auxetic Inconel muzzle break. The central image is a target's eye view of the device, and the other images are rotations from that position (Photo: Sintercore)

The finished design is shown above, with a target's eye view of the Sintercore Auxetic muzzle break in the center. The gases are preferentially directed upward and to the sides, but the internal structures that direct the gas backward to reduce recoil cannot be seen in the image. The final result functions quite well, as can be seen in the video below.

And the cost? The Auxetic is available at a suggested retail price of US$300. A conventional muzzle brake made of softer materials costs perhaps $80, while a competing upper-end muzzle brake made of Inconel is available for about $400. The word on the web is that Inconel is overkill for the functional purpose, but it looks and performs well. The real significance, though, is that Sintercore has taken a step toward a new method of designing and fabricating firearms.

Source: Sintercore

9 comments
f8lee
Here we go - how long until the Einsteins in Congress flail their arms looking for ways to prevent this from succeeding? Not that they will be able to - now that the technology is known it will arise somewhere else if stifled in the US.
Roy Murray
@f8lee; Congress has been patently unable or unwilling to do anything to prevent the proliferation of guns. Why should they start now? Besides, most of them are puppets of the NRA.
tampa florida
it almost seems that we are reaching the point where 3d printers are able to print themselves
asdf
@tampa Right now I think the biggest road block is the inability to 3d print electronic components (think resistors, IC's, capacitors). You might like to look at the reprap project, the aim is to create a self replicating 3d printer: http://www.reprap.org
Slowburn
An honest reading of. "A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed." requires that there be no limits placed on the weapons possessed by the people.
Bruce H. Anderson
Just like CNC was a step for machining products that would be difficult to do by hand, this is a step for making metal objects that CNC can't do. So whether is it firearms, medical devices, automobile parts, rocket engines, etc., there are lots of possibilities.
pmshah
@Slowburn You are absolutely right PROVIDED the first four words of this statement "A well regulated militia" are adhered to. Unfortunately this is the very aspect that is missing in real life.
Iceberg0311
@pmshah The militia referred to in the second amendment consisted of EVERY free able-bodied male aged 18 to 45 years. dangeroustruths.com/militiaandright.htm
bullfrog84
Any idiot with tube and some combustive substance, which can be made out of literally anything, can make a gun. Even if they outlaw them, there will still be guns a more likely people will make deadlier and stealthier guns to boot.