To take the bore sighting a step farther, use an unprimed 45-70 case in your BC chamber, you may have to make the flash hole bigger to use it as a peep sight for looking through the bore. It's preferable to have the rifle in a vise of some sort to help immobilize it when making adjustment, but can be done without it if you're careful.
If you want a laser bore sighter, the Cabelas unit for $40 works real well.
As for the off center reticle, I'd center the reticle first using the mirror method recommended by Leupold. Since you already know there's a problem, I'd start by making sure the 3 mounting holes in the barrel are aligned with the bore using a long straight edge on the side of the base, it shouldn't show any runout towards the muzzle. It could also be caused by rings that aren't quite true. Remove one ring and reverse it 180ยบ and see if that helps, if not, reverse the other ring to see if the reticle is closer aligned to the bore. As a last resort, and my first choice to begin with, get some Burris Signature Zee rings with the offset insert kit so you can literally zero the scope with the inserts without adjusting the scope.
Tim
The Leupold Answer Guide
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.
