Election results mark a continuation of the group's impressive success rate when making large investments on candidates.The National Rifle Association took a historic gamble in 2016, and it paid off in a huge way.The gun rights group placed multimillion-dollar bets on Donald Trump and six Republican Senate candidates locked in highly competitive races. It poured $50.2 million, or 96 percent of its total outside spending, into these races, and lost only one — an open seat in Nevada, vacated by the Democratic Minority Leader, Harry Reid. That race cost the NRA roughly $2.5 millionThe NRA’s big night came as a...