Defense Distributed, a group that is developing free designs for weapons made on 3D printers, tested out a firearm that has a plastic lower receiver made on a 3D printer. It successfully fired six rounds before splitting.
HaveBlue claimed in July to have fired his printed gun hundreds of times, which doesn't seem impossible given the quality of the printing. The part printed by the group is called the lower receiver, which is where a round is received from the magazine. Pictures show it to be very well made, and it appears to fit exactly to the other parts in the gun kit they used.
But the pressure of the recoil appears to have been too much for the "buffer ring," which separates the stock from the upper receiver. After firing just six shots, the gun split in two. It's a serious setback, especially considering they were firing a lower-caliber cartridge than the gun would normally shoot.
3D printed gun fires 6 shots - then falls apart (Thanks, Lew!)
Previously: Defense Distributed