One of the things that have prevented 3D printed guns from gaining popularity with the mainstream is the fact that they can't fire more than several rounds without wearing out. The plastic used to make the body of the gun is simply too fragile to accommodate the force of firing. A 25-year-old machinist has found an easy, although time-consuming, way to solve this problem.

Michael Crumling has developed ammunition he calls .314 Atlas, after the .314-inch caliber and the Atlas lathe he used to make his bullets. Each bullet designed by Crumling is buried deep inside and reinforced with a thick steel shell which absorbs all the force of firing, as opposed to traditional guns and other 3D printed guns where the force is taken by the gun's barrel or body. This way, gun owners can fire an "unlimited" number of rounds without deforming the firearms after several rounds.

"It's a really simple concept; it's kind of a barrel integrated into the shell, so to speak," Crumling said. "Basically it removes all the stresses and pressures from the 3D printed parts. You should be able to fire an unlimited number of shots through the gun without replacing any parts other than the shell."

The .314 Atlas represents another small step towards making 3D printed guns a viable alternative to conventional firearms, but Crumling's ammunition is far from becoming commercially feasible. Although the raw materials cost only $0.27 each and the gun was printed using a low-cost PrintrBot home 3D printer, it's not as quick to produce the bullet. Crumling says it takes an entire hour just to make a single round alone. Once fired, the bullets can be collected and repacked with gunpowder to be used again.

That should leave some room for lawmakers and gun control authorities, who have been battling with the budding firearm technology that can potentially allow anyone with access to a 3D printer to build their own guns without monitoring by the government, to create regulations surrounding 3D printed guns.

The Bureau of Alcohol Tobacco and Firearms (ATF), for instance, has challenged the reliability of 3D printed firearms in a video showing Defense Distributed's Liberator exploding from the impact of firing. However, Defense Distributed defended its product and called out the ATF for using the wrong printing methods or wrong ammunition, saying the ATF is using scare tactics to keep gun enthusiasts away from 3D printed guns. Still, the company admits that 3D printed guns made with plastic, including its own Liberator, takes on some damage every time a round is fired.

This is where Crumling's ammunition could play a significant role in turning 3D printed firearms, even semi-automatic and automatic ones, more popular.

"That's the main reason I developed these, and that's the next step," Crumling says. "This is a building block for the future of 3D printed firearms that will enable people to develop semi-automatic and - if you had the proper legal paperwork - even fully automatic weapons."

Crumling is not selling his ammunition, but he has uploaded his design and shares it for free. However, he says he could start taking on orders to produce the bullets if an adequate number of enthusiasts ask him to.