I watched a Randy Newberg YT clip last night in which he explains how a non-verticle reticle causes cant related POI shift at distances other than the zero'd range. His tutorial has easy to follow graphics and he shows how he achieves action-to-scope truing using some clever optical device. But I got to thinking I could probably MacGyver a way to achieve the same outcome...
As it happens, the scope on my 30.06 was slightly off and needed fettling so I had a candidate for the project.
First up I lashed a visually straight bar onto the flat top edge of of the receiver action and ensured that there were no slivers of light where the action and reference bar married
View attachment 175280. Next I suspended a plumbline 2m in front of the rifle and manouvered the rifle bench to face that. Scope was set on lowest zoom, reticle and plumbline almost overlapping in sight picture. Then I canted the stock until declared level
View attachment 175281. Reviewing the sight image now, the plumbline and reticle were
not in lockstep [see next post for before and after sight pics] and a spirit level placed on the top turret further confirmed cant
View attachment 175283. So I loosened scope clamping screws and rotated scope perhaps 3 degrees anti-clockwise. I double checked that rifle action was still level and checked both spirit level and plumbline sight picture before tightening scope screws. One more final check after that
View attachment 175293.
So the before and after sight images looked like...