POLSON — It’s a highly specialized business, carving rifle and shotgun stocks out of blocks of walnut and maple and then custom-fitting them to each gun and gun owner. Kelly Clairmont said there are maybe 100 people in the United States who do it for a living. “And four of them are right here in Polson,” he said. And all four of them got their starts with Bob James, a longtime custom stock maker in Polson. The others eventually formed their own company, S&S Plus, while Clairmont in 2009 bought out James’ business, which is now called Montana Custom Guns,...