What I do is faf around first working out eye relief , mark on tube as described above where to mount scope relative to rings.
Put gun in a vise (put a towel around the stock o prevent damage)
Use cloths line level on action to ensure level.
Install rings again (if not like a tikka where you can use the middle of action)
Mount scope, lightly tighten rings
Place level on top of scope: Leopold you can use the caps or Zeiss take the caps off and use the adjustment bit which is level
Tighten each screw slowly alternating between rings
Ensure it remains level throughout
Done
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