3D-printed guns: inaccurate and vulnerable to catastrophic failure

We should not be complacent about 3D-printed guns, but for the time being it is the user who faces the greatest risk

The Liberator printed gun made headlines around the world in May, but it is a rudimentary device only capable of firing one shot. Photograph: EPA

Finding 3D-printed gun parts in the Manchester suburb of Baguley, as the police have claimed, seems like a fearful omen of the future. Greater Manchester police hailed it on Friday as a significant discovery, but with the current state of the technology, the person most in danger was probably the owner the "gun" themselves.

In fact, the police don't actually seem to have found gun components, 3D-printed or otherwise. The two items they showed at their press conference on Friday appeared instead to br 3D printer parts. Officers maintain, however, that the haul is disturbing, given that they also seized gunpowder during the raid.

The concept of a 3D printer that can print a 3D printer is itself vaguely concerning (isn't that how Terminator starts?) but it is still a relief compared with the prospect of downloadable weaponry on every street corner.

But we should not be complacent. Even if this case turns out not to be a printed gun, there will be one in Britain soon. The technology is already fairly cheap and widespread, and getting more so all the time.

For the time being, however, the risk from a 3D-printed gun is mostly hypothetical for two reasons: they aren't very good, and you can't print bullets.

At its heart, a gun is a simple machine. The cartridge goes in one end. A firing pin hits it, gunpowder explodes, and rapidly expanding gases push the bullet out of the barrel very, very quickly.

The principles are so simple that by the 1950s, zip guns had become the scourge of New York. Street gangs would hammer together wood, antenna housings and elastic bands, buy (or steal) real bullets, and fire them at one another.

The Liberator, the 3D-printed gun that made headlines around the world in May, works on the same principles. Except for the firing pin, which still needs to be made from metal, the entire gun is printed in 15 separate parts, the plans for which can be downloaded from a number of sites, including the filesharing hub The Pirate Bay, using a 3D printer. It all sounds futuristic, but at heart, the Liberator remains little more than a zip gun.

The gun is designed only to deliver one shot. It is inaccurate, with a short barrel that struggles to point the bullet in the right direction. That short barrel also means it is underpowered, even for a handgun, with most of the explosive energy dissipating harmlessly around the edges. To top it all, the guns are still vulnerable to "catastrophic failure", as New South Wales police discovered when testing the plans earlier this year.

"We fear that the next story will be about a child blowing their hand off while experimenting with a 3D-printed gun," wrote Jason Rowley on the 3D printing blog Digits2Widgets. "This type of accident is the immediate danger of the project and will happen long before anyone is deliberately killed by one of these tools."