Tests conducted by ballistic labs and a university in England showed that guns made with thermoplastics on 3D printers are far more dangerous to the shooter than the intended target.
A video released by the BBC showed in every case the 3D-printed guns broke or exploded under the chamber force of a bullet being fired. Pieces of the plastic gun were strewn around the firing range – even embedded in the ceiling.
The university conducted its test in collaboration with West Midlands Police's National Ballistics Intelligence Service (NABIS).
Simon Leigh, a professor with the University of Warwick's School of Engineering, printed and tested the gun based on downloaded CAD drawings of the Liberator gun, which was independently developed in the US by Defense Distributed.
Speaking to The Independent, Leigh said the test results on the guns "ranged from small failure to complete catastrophic failure."
NABIS Detective Chief Superintendent Iain O'Brien said there's a "curiosity factor with 3D printers and those interested in playing around with the technology may not realize the danger they are facing."
"We need to make people aware that producing a firearm in this way is illegal and could cause serious injury to the person holding the gun," O'Brien said in a statement issued by the University of Warwick.
Defense Distributed has demonstrated its Liberator 3D printed gun successfully. The gun, however, has a limited lifespan, and it typically fails after a number of firings. The gun was made using ABS thermoplastic materials that were extruded by a RepRap (replicating rapid prototype) 3D printer.
Two of the mostly widely used materials in 3D thermoplastic printing are Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA). ABS is petroleum based, while PLA is derived from organic materials, such as corn starch. PLA is more brittle than ABS.
Contacted about the UK gun tests, Defense Distributed's founder Cody Wilson said that without seeing test details he could only make assumptions about why the guns failed.
The New South Wales police in Australia, Wilson said, did their tests using PLA filament and 9mm round. "Their propaganda was identical. Don't download it, it's illegal and dangerous to use," he said in an email response to Computerworld.
Wilson also pointed to an Israeli test of the gun that didn't use an "acetone vapor to treat the barrel."
"They also used 9mm [rounds]. They have video of the barrel splitting," he said.
Wilson said that perhaps the best clue comes from a video released by the US Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). The ATF, he said, used ABS-based VisiJet filament from 3D Systems "and some kind of acrylic springs.
"The dirty secret about these police tests is that Liberator springs don't even work in the weaker materials that would make the gun explode. So you're getting hybrid guns built expressly to destruct for maximum spectacle," Wilson said.
Wilson pointed to a video of a test conducted by the ATF. It demonstrated in at least one video that the gun could sometimes be fired safely. Overall, however, the tests showed the gun to be unsafe.
The ATF demonstrated The Liberator 3D printed gun could be successfully fired.
"Police agencies and governments have been testing the gun for over a year now and invariably there's an interest in showing it fail," Wilson said. "But if made to the specifications that come with the files, the gun never fails catastrophically and each barrel can shoot a number of rounds before needing to be replaced. This is a case of convenient disinformation...."
The 3D printer that makes plastic guns uses a process known as fused filament fabrication where layer after consecutive layer of thermoplastic filament is laid down on a platform. A motorized extruder is controlled by CAD designs as it lays down the heated plastic.
3D printing services company Solid Concepts last year demonstrated a .45 caliber metal gun that functioned exactly as a standard pistol would. That gun was created through a 3D printing technique known as laser sintering.
Solid Concepts' 3D printed replica of the storied M1911 semi-automatic, which served as the U.S. military's standard-issue sidearm, blew through thousands of rounds. Yet, the weapon was printed on a machine that costs tens of thousands of dollars , took days to create and required hand finishing.