The caricature is familiar—loopy red-state troglodytes obsessed with guns, so careless or crazed that they put innocent lives in danger and all but require the government to intervene with draconian laws. But is caricature the best way to conduct a debate over guns and gun rights? A few years ago, Dan Baum, a gun owner and self-described liberal Democrat, set out to see for himself what America’s gun culture really looked like. In “Gun Guys: A Road Trip,” he offers an account of his travels through gun-owning America.

Mr. Baum concedes that most of the gun owners he encountered on his cross-country journey “had taken up the responsibility to handle incredibly dangerous weapons with great care.” They were “careful, sober, self-reliant individuals.” He doesn’t see much point in “insulting, belittling, and maligning those people—the 40 percent of Americans who owned guns.” After all, most gun owners “hurt nobody” and, as he notes, most gun-control measures don’t save lives anyway.

And yet Mr. Baum can’t help serving up predictable anti-gun stereotypes: the 24-year-old who lives with his parents and spends every spare cent he has on an assault rifle; the drug-rattled couple that buys a gun on a lark and ends up using it to settle an argument; the Internet wingnut who, responding to a question about the United Nations possibly infringing on Second Amendment rights, spews obscenity and vows to fight the U.N.’s men in blue helmets. And then there is the yokel at the gun show facetiously selling pellets that will give their owner the powers of Barack Obama: “They’ll raise your taxes, take your guns, leave your border unprotected, and surrender two wars.”