As an update to this old thread: Rep Steve Israel, D-NY 3rd District introduced bill HR1474
that would ban so called undetectable firearms, home made firearms with non metallic receivers, and home made plastic magazines. Factory all plastic receivers, like some injection molded AR-15 receivers, and magazines are unaffected.
The law has not been updated to reflect the increased sensitivity of modern metal detectors, does not take into account modern screening processes and technologies like x-rays, and does not consider how unenforceable it is with modern $600 3D printers becoming more popular. Also many details of compliance are quite vague.
By supporting home gun smiths the NRA could further discredit the ridiculous "industry shill" meme.
have good articles about it. Defence distributed's forum DefCAD
has all of the details.
More analysis from a group that worked with Israel to draft the bill: www.publicknowledge.org/blog
Rep Israel's web page
links to many articles about this issue.
In 2003 it passed by a voice vote, and unanimous consent. It better not go that way this time.
Edit: A new article by the examiner
shows that plastic magazine manufactures would need to get a manufacturing FFL if the magazine body does not contain at least an once of steel.
Rep Israel also proposed and then backed down from an internet crackdown to stop the proliferation of magazine CAD files.