Here's a tip for the OP. I've seen that tactical rings priced above about $75/pair usually have all surfaces machined, including the inner ring surfaces.
Tactical rings that are priced below about $75/pair are usually cut from extruded bar stock. The ring surfaces that grip the scope tube usually have extrusion marks and are not precisely cylindrical. Otherwise, they have good strength. Burris tactical rings are an example of extruded rings.
Lapping these extruded rings will make them cylindrical and will make the rings coaxial (properly aligned). If you have access to a lapping bar you can save a few bucks by buying extruded rings instead of the more expensive and precise machined ones, and then lapping them.
Last edited by bruce_ventura; 07-15-2013 at 11:24 PM.