OK, I'll synopsize without trying to explain the technical aspects of the tools the Robert Louis gauge is attempting to compete with or replace. My synopsis is; The Robert Louis gauge works. It has been demonstrated to me by the makers several times. The makers are really nice guys, very professional, and are "like minded individuals". They are talented engineers who manufacture other items also. We all need to own bore measuring devices and Robert Louis makes one of these devices. The company has generously sponsored shooting events that I have been affiliated with. I like them and I like their products.
