I'll have to respectfully disagree, guys. After having install literally hundreds of bases, rings, and scopes made by every manufacture imaginable and cutting them with a "ring reamer" I have yet to see a set of mounted rings that are in very close agreement. Doesn't matter wheather they're made by Burris, Leupold, Redfield, ect., ect. I believe the variation is probably in the receivers more than the ring/bases themselves. Those mounted on the custom actions I've used (Big Horn, Borden, Stiller, Defiance, and the new Surgeon Round action are much closer than any of the 'production' actions. Lapping takes too long, hence, the reamers (1" & 30mm). Put the reamer in the mounted rings, install the top halfs and snug them enough you can still turn the reamer with a wrench, make 2 or 3 'rounds' with the tool, remove the reamer, and it quicky becomes evident how little contact is being made. May not be the "cure all", but what one thing is?