When fitting scopes I will "zero" the scope. That is, set windage and elevation in the middle of their adjustment, this has the crosshair optically centred with least chance of abberation or parrallax. (And if you're inclined to twiddle turrets, gives you max avail adjustment)
If rings aren't good I will clean them up with a file to 90%+ contact, achieves same as lapping, just without using lapping tool. (I'm not opposed to lapping tools, but if I can get away without grinding paste near a gun, I will)
I fit the bottom half of rings to the gun and lay the tube in it and "boresight", if it's too far left or right I will swap the rings front to back, or 180 degrees (one screw left and one right, ie) to get it as close as possible. Then put the top halves on and nip them up (this has NAF perfect contact between rings-scope body), slack the mounts and torque the top, then torque the mounts, boresight again then zero by shooting.
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