A country with more guns than people is plagued with gun violence: suicides, murders and mass killings. Igor Volsky says the NRA has distorted American history, made guns a matter of “social identity” and frightened most politicians. But polls show regulation is widely supported, even among gun owners, and he’s optimistic. He explains the argument laid out in his new book, “Guns Down: How to Defeat the NRA and Build a Safer Future with Fewer Guns.”