What Gundoc said about the mirror method centering the scope "relative to itself" makes an awful lot of sense. I've done the click and count method very carefully before, then checked it with the mirror and it would be 5-6 clicks off from actual center. If the obj. is firmly squared with the mirror I don't think you can go wrong.
John
John,
I have had the same experience, and I don't know why. For all I know, it may have to do with the quality and flatness of the mirror as well as any "unsquareness" in the scope. As long as it is not too far off, I don't worry about it. If it was way off, I suppose I would be calling the manufacturer, often Leupold in my case.
Gun Doc