The Evolution of 3-D Printed Firearms

By Kyle Mizokami

In March, a Website dedicated to 3-D printing firearms announced one of its members had developed a lower receiver for a Colt CM901 rifle. It’s a small — but evolutionary — step toward the development of firearms that pretty much anyone can download off the Internet.

The CM901 is the bigger, badder brother of the ubiquitous AR-15. The CM901 has a similar design, but fires the heavier and more powerful 7.62-millimeter bullet, resulting in greater range and killing power.

A group of gunsmiths associated with PrintedFirearm.com developed the CM901 lower receiver and uploaded an animated gif of a live-fire test. The clip is five seconds long.

The CM901 is a modular design, so the rifle can shoot lighter 5.56-millimeter rounds, too. The group used a XYZ Da Vinci printer, which retails for around $500.

By the standards of 3-D printers, that’s cheap.

Remember — this is an evolutionary development.

Downloadable blueprints for 3-D printed AR-15 lower receivers appeared on hobbyist forums several years ago. All you need is a 3-D printer and enough thermoplastic, and you can build yourself one.

Cody Wilson of the gun rights organization Defense Distributed — which built the first fully 3-D printed pistol — developed an AR-15 lower receiver that can fire hundreds of rounds.

But it took a lot of trial and error, because the receiver’s components had to withstand recoil and the stresses from moving parts. Earlier version of Wilson’s AR-15 lower receiver broke after firing only a few bullets.

Rifles chambered for 7.62-millimeter are heavier — usually by about four pounds — and suffer from even more recoil than the AR-15.

It’s not clear if the 3-D printed lower for the CM901 will hold up after more than few seconds of rapid fire. All we see is a short clip.

“It has been tested, fired with little to no issues,” the group stated.

In any case, advances in technology hold the promise of making durable, reliable parts for 3-D printed guns. That means more powerful guns … that last longer.

Recently, 3-D printing start-up MarkForged invented a printer called theMark One, which can make objects out of carbon fiber, Kevlar, fiberglass and nylon.

Carbon fiber is a composite material made from threads of carbon bound by a plastic resin. It’s known for being tough and lightweight — and can replace metal in everything from aircraft to cricket bats.

Carbon fiber exists in the AR-15, but the composite is limited to the rifle’s hand guard and butt stock.

But MarkForged has claimed its carbon fiber has a greater strength-to-weight ratio than 6061 T-6 aluminum — which comprises standard AR-15 and CM901 lower receivers.

Which sounds perfect for making guns. Buy a printer, load it with carbon fiber, input a file with the specifications for a lower receiver, press a button … and wait.

Wilson said he ordered a MarkOne at the introductory price of $8,000, but the company told him earlier in March that his order would not be honored. MarkForged’s terms of agreement forbid customers from using its printers to make guns, the company claimed.

That was not actually true, but Defense Distributed was out a printer all the same. Wilson promptly went ahead and posted a video on YouTube offering a $15,000 reward to anyone who could send him a MarkOne. Four days later, the gunsmiths sent a cryptic tweet — “We have it.”

Defense Distributed has been quiet since, no doubt busy experimenting with guns made out of carbon fiber.

Carbon fiber might be the answer to many a 3-D gunsmith’s prayers, but it still doesn’t mean you can print an entire rifle with it. For one, high-caliber barrels must be metal, or they’ll break.

At least one company advertises carbon fiber barrels, but a closer look reveals they’re simply steel barrels reinforced with carbon fiber.

Still, the technical challenges are only part of the point.

Desktop weaponeers focus on printing lower receivers — because they’re subject to federal regulations. You can’t make a working gun without a lower receiver — and they usually come with a serial number stamped on them.

As far as the Bureau of Alcohol, Tobacco and Firearms is concerned, a gun’s lower receiver is the gun. Everything else, including the barrel, you can buy over the counter with no questions asked.

But private citizens in the United States have the right to make their own firearms — and lower receivers — without any oversight from the federal government.

It’s a complicated process and takes metal-drilling machine tools. A 3-D printer simplifies this process, and could allow citizens to build their own rifles without registering them, going through background checks or waiting periods.

We don’t know if Defense Distributed will succeed in printing a carbon fiber lower receiver. But at some point, rapid advances in 3-D printing technology ensure that someone will.

This piece first appeared in War Is Boring here

Kyle Mizokami
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