Springfield-based Smith & Wesson Holding Corp. climbed the most in two months to lead a rally of firearms manufacturers as traders speculated that President Obama’s reelection will spur gun sales. After sidestepping gun-control issues in his first term, Obama last month said he would consider reintroducing a ban on civilian purchases of military-style assault weapons. Firearm sales have grown 10 percent annually since 2008, when Obama was first elected, compared with a 7 percent rate from 2001 to 2007, according to Benchmark Co.