To align rings perfectly with each other,
Sinclair International sells a neat kit that is very simple to use. There
are others on the market that may work equally well.
I tried it first on a cheap gun with cheap rings and it was simple to do. I
have since used it on all of my centerfire rifles. It is a very straight forward
process and the kit instructions are very clear.
Since I can, I thought I would share some pictures of the process with you.
The Sinclair Scope Ring Lapping Kit
Ready for second round
Slide and Rotate against compound
Remove compound to see progress

The instructions say the bar should make about 75% contact with the bases when
finished.
Evidenced here by lack of the outer finish. I quit here which is probably a
little short of 75% but this was my first attempt and I did not want to over
do it.
Here are some additional pictures added in 2008
Back Ring after getting
started.
Back ring when finished.
Front ring after
getting started.
Front ring finished.