Yes there is an advantage to having the scope optically centered at mounting, if the bore is out of alignment with the mounts by very much, it will show up immediately when it's bore sighted. That's why some folks end up having to shim bases or use Burris offset inserts due to misalignment issues. Using a mirror to center the reticle costs nothing and is Leupold's recommended method of doing so. You also dont' have to worry about locking the
ajustments up by bottoming them out when counting clicks.
Tim
Quote:
Centering of a scope's adjustment dials
The elevation and windage adjustments of a scope are easily centered. Place a small mirror against the objective end of the scope. That would be the end farthest from your eye as you look through the scope. Make certain that the mirror is large enough to cover the entire objective. It must also be flat against the objective. With the scope's power selector ring set at the lowest magnification, look through the eyepiece as you would while aiming at a target. If the scope's windage and elevation adjustments are off center, you will see two images of the reticle (cross-hair). To reach the center of the adjustment range, simply turn the elevation and windage dials until you see only one image of the reticle.
Leupold mirror method
