The Nikon scope has arrived and so off comes the BSA scope and we need to de-grease the ring hardware for the permanent installation. There are lots of choices in anyone's kitchen or garage:
I chose isopropyl alcohol because it's easy to work with in confined spaces.
Here's the new scope sitting in the rings. It's a Nikon Buckmasters 6-18x40 with a mildot reticle that ranges at 12x.
I tried the bathroom mirror test on it and the reticle was perfectly centered.
After the usual procedure of leveling the gun, boresighting to level the scope, and torquing down the rings, here's the result:
Perfectly level, 3/4 division high and 3 3/4 divisions to the right. No scope adjustment yet. I was so surprised that the windage was so far off that I took the scope out of the rings, checked the bathroom mirror again (it was still centered) and torqued down the scope again. Same result.
Well, at least it seems to be repeatable.
I read somewhere on the web that some scopes, even expensive ones, do not have their optical center and their mechanical center in the same place. It has to do with the design of the scope and how much the turrets protrude into the main tube. The designers want the reticle to be centered in the lens system because that's where the image is sharpest, but that may conflict with how many clicks there are in each direction. So sometimes the designers have to compromise.
Well, that's what I've heard!
I'll try to get to the range soon and give it a try.