Note the open-top design.
Note the open-top design. Michael Crumling

As police from Germany and Australia will tell you, 3-D printed guns are likely to be as fatal to the person firing as they are to anyone else. This is true primarily for poorly made 3-D printed guns using weaker plastics that can’t absorb the explosive shock from the gun blast. Without specially designed ammunition, the stress of firing rounds risks exploding the gun — and injuring the person holding it.

To fix this issue, Pennsylvanian machinist Michael Crumling made a special type of ammunition that doesn’t break a 3-D gun when fired. His special Atlas rounds are .314 caliber, a size sometimes used in rifles. However, these rounds look a bit different from normal rounds of ammunition. Typically, there are two mains parts of a round that are usually visible: the bullet, the little pointy part sticking out from one end, and the shell, the casing that surrounds the bullet. In the Atlas rounds, the bullet part doesn’t stick out but is instead recessed an inch deep inside the outer metal casing, like a turtle in its shell. Here, the round’s thick shell functions as both a barrel and a shell, absorbing the explosive force of the gunpowder and channeling it forward.

Weapons photo

Atlas Bullets

To shoot these special bullets, Crumling also specially designed and printed his own gun, which resembles Defense Distributed’s “Liberator,” the first 3-D printed gun. There are some key differences, and chief among them is the lack of a closed barrel on top. Instead, the thick shells of the Atlas .314 rounds keep the bullet pointed the right way, and then eject when the bullet leaves. It’s a clever solution to the challenge of weak materials that’s limited the potential of printed guns.

Weapons photo

The Gun’s Special Open Top

It’s also a gun that’s harder to replicate. Crumling didn’t print his Atlas rounds, he machined them, using skills and tools that aren’t necessarily available to everyone with a 3-D printer. Given the time and skill demands of making ammunition like this, it’s less likely to have an impact in the United States, where conventional guns and ammo are readily available. However, it may make a bigger splash abroad, in places like Germany and Australia, where gun controls are tighter. Or in Japan, which just sentenced a man to two years in prison for printing a gun.