MrSeb writes: "In its continuing mission to build a “Wiki Weapon,” Defense Distributed has 3D printed the lower receiver of an AR-15 assault rifle and tested it to failure. The printed part only survives the firing of six shots, but for a first attempt that’s quite impressive. And hey, it’s a plastic gun. Slashdot first covered the 3D-printed gun back in July. The Defense Distributed group sprung up soon after, with the purpose of creating an open-source gun — a Wiki Weapon — that can be downloaded from the internet and printed out. The Defense Distributed manifesto mainly quotes a bunch of historical figures who supported the right to bear arms. DefDist (its nickname) is seeking a gun manufacturing license from the ATF, but so far the feds haven’t responded. Unperturbed, DefDist started down the road by renting an advanced 3D printing machine from Stratasys — but when the company found out what its machine was being used for, it was repossessed. DefDist has now obtained a 3D printer from Objet, which seemingly has a more libertarian mindset. The group then downloaded HaveBlue’s original AR-15 lower receiver from Thingiverse, printed it out on the Objet printer using ABS-like Digital Material, screwed it into an AR-57 upper receiver, loaded up some FN 5.7x28mm ammo, and headed to the range. The DefDist team will now make various modifications to HaveBlue’s design, such as making it more rugged and improving the trigger guard, and then upload the new design to Thingiverse. Thus the open-source circle is complete!"