Not a lot of help I know ... but maybe. I have a perfectly good Weaver scope I have had for a long time and it has been mounted on a variety of rifles with no problems. It has been on the shelf or a while until this last week or so when I purchased a new 17HMR (CZ455). I thought OK the old weaver can go on there, so went up into my box of 'bits' where I have a selection of rings and bases. I picked out a set which looked almost new , if not new and they were wired together as a pair. Fitted them and the scope....looked good. Went down to my wood to zero and to start with found I was almost on maximum elevation just bore sighting. Hmmmm???? Fired a couple of shots and they were 4 inches low, smack in the centre line and I ran out of adjustment ... HMMMMMMM ?????????
I needed to have the rifle up and running that evening, so dived back into my box of bits and found another set, different make, slightly higher. Set them up, fitted another scope and the rifle was grouping ragged holes at 80yrds.
That set me thinking so I checked the Weaver scope, no damage I could see and it was strange that it was shooting perfectly centred on windage. OK, check the rings, which to the eye initially looked exactly the same. However, I felt that one base of one ring was just slightly bigger than the other, but hardly. I got my steel rule and checked the measurements and the base of one was 0.5mm taller than the other. Hardly noticeable with the naked eye. I could have binned that old Weaver as a result, so lucky I didn't.
I repeat, these rings are identical in every other way. I just wonder if the two had got mixed between batches. I've had them close to 25yrs, so nothing I can do or wish to. Just thought I would bring it to notice in case y'alll have a similar problem...don't ditch that scope till you check the rings.