Very interesting!
One thing many people don't realize about the common pair of pointy-tipped mounting bars is that just because the points of both bars align doesn't mean the rings are aligned. This is easily proven by taking two pencils and putting the points together. The angle of each pencil can vary considerably.
Paired mounting bars are much more accurate when the flat ends are matched up, rather than the points. If you use the points, it helps a lot to place a small straight-edge along the bars.
I just received some really interesting alignment bars (1" and 30mm) that have slots so the base screws can be tightened when the bottoms of the rings are in perfect alignment. I haven't used them much yet, but they hold a lot of promise.
