We’re at Desert Hills Shooting Club near Boulder City, and Paul Barrett steps up with a Glock 17. He fires the 9 mm semi-automatic pistol 18 times in about five seconds and hits the target every time. In that five seconds, he demonstrates why the Glock is beloved by gun enthusiasts and police officers alike. It’s fast, reliable and offers a lot of stopping power, with three times the number of rounds as the old police favorite, the Smith & Wesson .38 revolver. Barrett, in town this week for the Shooting, Hunting, Outdoor Trade Show (SHOT), the big firearms convention,...