With a sporter contour barrel, you can usually use medium rings with that setup. If you're getting any newer production Leupold bases, check to make sure the difference in the height is correct before you mount them. I forget exactly what it is on a M70, .138" I think, but I have been seeing a lot of base sets that weren't right and didn't allow the scope to be zeroed. On a M700 front base there's enough meat to cut them down to allow zero, but a M70 front base is really short already and the front ring will hit the reciever if the base is milled enough to allow the scope to center. The older Leupold bases didn't have this problem, don't know when there were changed but they are a problem now. (The Rem 700 ones have this problem about half the time as well.)
