upnorthbacon,
I have 4 sets of them on four of my Contender barrels. I think they are great, but I have never tried any of the other multi-ring systems to use a comparison. I have never lapped them. I use a 1" wooden dowel rod to get them aligned. As I am aligning them, I place the 'scope in the bottom portion of the rings from time to time. I make sure it fits nicely and that the rings appear to be in line perfectly with the 'scope. That is about the best I can expain it. I will definately buy more as I get more T/C Contender barrels. Good-luck...BCB