You’ve mounted red-dot optics on ARs for years, never received a complaint and the process has become so routine that you rarely consider mentioning the value-added service. Most of your loyal customers prefer doing it themselves, anyway, but the market has changed in dramatic fashion.

The National Shooting Sports Foundation estimates 40 percent of the record-setting 21 million firearms sold last year went home with a first-time gun owner. That comes to another 8.4 million...