Thread: Out of alignment reciever ring mounts Rem700

Good thing I have a fair crop of hair as this has been driving me nuts. I have recently turned a 6BR into a 243AI on a Rem700 action. Previously the rifle ran with a EGW one piece base, nightforce rings and a Sightron SIII scope. Now I have a Swaro scope and had planned to run Talley Ultralight rings. With the Sightron I had no issues (it did have 100MOA internal windage though) but with the Swaro it looks like my rear ring is on the piss. Initally I ran out of windage in the scope trying to get onto paper. We lapped the shit outta the rings as they were not great (new to Talleys, and general consensus was they do usally require a good lap). Tried a second set of Talleys and they too had the scope out of alignment (although not as bad). I have now gone to Leupold steel rings with the rear windage base. Not really what I want though. All those screws and play in the bases don't cry precision to me.
Anyway the guts of what i'm asking is. How can I prove the reciever is drilled croocked? I kind of have by default but would like to know for sure, and any thoughts on what to do next?
FYI the barrel was fitted by Trueflight and the action has been trued so I doubt the barrel is on the piss.