As the Senate moves toward a comprehensive gun control bill that would include extensive background checks that would threaten the legality of private transactions, House Republicans are taking a different tack on a gun bill: House Republicans' focus on mentally ill criminals has become sharper in recent days, as a bipartisan plan to expand background checks on prospective gun buyers gained momentum in the Democrat-led Senate - thanks in part to emotional calls for action in Washington by family members of victims of the Newtown, Connecticut, school shooting. Boehner has pledged that the House will act on any gun bill...