As long as the scope is plumb, it’s all good. I got the idea to get the rifle natural to my body and then level the scope from Tubb. Totally helps me get into NPA faster. Not necessary, but faster.If you truly want to check, hang a plumb line at 100m and get behind the optic. Scope leveling is a bit controversial. I tend to favor it being perfectly square to the bore on the vert axis. However, a lot of excellent shooters like David Tubb do it totally opposite and their rifle is a bit canted while the scope is level to the horizon. If you know and validate your holds, it all works.