Sen. Charles Schumer said Monday he is putting his full support behind legislation aimed at stopping the production of undetectable plastic guns that can be made using relatively cheap 3-D printers. A Texas-based libertarian group has successfully been able to produce a functioning plastic handgun using a 3-D printer that anyone could purchase, Schumer said. He said the group plans to post on the Internet how to go about making this cheap, but functioning weapon that could pass through metal detectors at airports and elsewhere. Schumer (D-N.Y.) said he is joining Rep. Steve Israel (D-Huntington) who has pushed for new...