SAN FRANCISCO (AP) – It sounds incredible, but a group is working to download a gun’s design and build it on a 3-D printer.

There wouldn’t be any background checks for such a gun and that prospect is disquieting to gun control advocates.

New York Rep. Steven Israel says that the possibility of such guns is reason enough to renew the Undetectable Firearms Act. That law makes illegal the building of guns that can’t be detected by scanners, but it expires next year.

A group called Defense Distributed is claiming to have created downloadable weapon parts that can be built using advanced printers that use plastics to create 3-D objects with moving parts.

“Wiki Weapons” project leader Cody Wilson says the group last month test fired a semiautomatic rifle built with some 3-D printer parts six times before it broke. No independent observer was there.