BOSTON - To hear Mitt Romney talk on the campaign trail, you might think the Republican presidential candidate had a gun rack in the back of his pickup truck. "I purchased a gun when I was a young man. I've been a hunter pretty much all my life," he said this week in Keene, N.H., to a man sporting a National Rifle Association cap. Yet the former Massachusetts governor's hunting experience is limited to two trips at the bookends of his 60 years: as a 15-year-old, when he hunted rabbits with his cousins on a ranch in Idaho, and last...