DALLAS—Larry Herwig, a 60-year-old dentist, surveyed the display of gun silencers on the exhibition floor of the National Rifle Association annual convention here with an expert’s eye.

“I actually have some, but I’m always looking to purchase,” said Dr. Herwig, an avid hunter who lives in the Dallas area and owns eight of the devices. “I like the noise reduction because I have hearing issues. If you like shooting…it’s been a blessing.”

Long...