As per my first three paragraphs, looking down into the 'scope objective against a bright background. The rest is just niceties that do matter for some of us.Sounds like a lot of rigmarole. Why not just line up the verticle cross hair with the centre of the bore, by eye?
i have the choice of glass for one rifle one rail been working for me so far but then again wot do i know
my last ****ed scope test .
and before I get well its off to the left it was development test after a rebuild
Choose your building carefully.The major assumption is that the receiver, the rings and the scope outer construction are in any way horizontal or perpendicular to the vertical reticule stadia
Google Image Result for https://geographical.co.uk/media/k2/items/cache/ba0dcc459ba28dad37cba99e09a9c5b8_XL.jpgThey seldom are....
Only one thing can be used to reference the vertical nature of the reticule
That is the reticule itself
Mount the scope loosely in the rings
Shoulder the gun
Line up reticule on the edge of a building
Tighten rings using a diagonal sequence
Unless you are waaaaaaay off or shooting at 1000yds it is unlikely to make any difference