While holding the record for the least-productive and most unpopular Congress in memory, the Republican-controlled House took a sudden turn Tuesday and passed by voice vote a 10-year extension of a federal gun control law. That’s right, gun control, an issue that typically raises the hackles of the GOP, making the House’s quick action all the more stunning. The reason for the hurried burst of bipartisanship is a 10-year extension of the Undetectable Firearms Act, due to expire Monday, which mandates that all guns include metal parts that are detectable by screeners used at airports, courthouses, and other venues where public safety is at risk.