On a recent flight, I found myself seated next to a man I’ll call Rick, who was keen for conversation. We established that we are both lawyers. Rick works for the government, and I explained that I lead a gun violence prevention organization. Rick took that as an invitation to talk about guns. A self-described “2A fanatic” from Texas, Rick grew up with guns and today owns more than 40 firearms. He considers himself a collector, and many of his guns are antiques — he’s not interested in assault-style firearms — and he makes his own ammunition from recycled casings....