"Gunfluencer" Brandon Herrera is trying to beat an incumbent in the Texas district. Illustration: Benjamin Currie/HuffPost, Photo: Getty Images

SAN ANTONIO — Brandon Herrera is a 28-year-old YouTube gun influencer with more than 3.4 million subscribers and half a billion views. In one 17-minute video, Herrera, in a tight black T-shirt and backward baseball cap, reenacts the killing of President John F. Kennedy Jr. using a replica head that contains a condom’s worth of fake blood.