I have a set of Weaver pivot rings and bases on an old Ruger .44 Carbine and found that as others stated, I had to hold the reticle "into the wind" so as to keep it vertical/ horizontal when the cap screws were snugged up.
I also have a set of 10 year old Weaver 4x4 rings that, while not all that pretty, do eliminate the problem of the scope rotating inside the rings when tightening the cap screws.
