I have one.....
And so do a bunch of other shooters in our Region.
It is a handy way to check your rounds, and yes, I know that it simulates placing a round between centers, and is not quite as accurate as far as ascertaing total runout as some other designs,, but it does give you a darn good idea as to where you are.
It can also straighten the rounds, I have done this once in a match, (trying to improve on .002), and I doubt I will again.
I think a lot of people rag on this little gizmo because it was supposedly some one else's design. That might be true, but in his usual fashion, Lester steps up, has them made, and sells them at a rather reasonable price.......jackie