Originally Posted by
Portzy
Yes, problem solved. Bighit, thanks for your kind offer, I replied but your inbox is full.
As said earlier, I spun the mount round and refitted it, it is a Sports Match one piece. This did nothing to improve matters as when I got somewhere near zero the poi would shift again and by a large margin. Now, I have never liked the "look" of this mount as it fits to the Lightning, despite reversing the clamping plate more than once the clamp never sat true to the rest of things in that the claw either seemed to be trying to roll itself out of the dovetail or wasn't engaging enough, and then the penny sort of dropped, it was a 9-11 mil mount and the BSA has 12 mm dovetails!
So I got my hands on a two piece BSA specific pair,TO6C, and fitted those and all is now well.