Years ago in handgun shooting competitions, a few competitors started installing red dot sights (RDS) on their firearms to give them an edge in winning matches. At first, the RDS were adequate, but had a limited life. They were also fairly bulky and, generally, a gunsmith’s services were required to mount them.

As is often the case, these RDS innovations pursued by match competitors drew the attention of people who use guns in real life-and-death situations. It took years for...