Maybe I'm overthinking this, but humor me for a moment if you will.

I've been leveling my scopes on my model 12 actions by using a very sensitive Machinist's Kerosene Level across the turret cap and parallel blocks mounted to the tang of the action. But it recently occurred to me that, although this might get me in the ball park, it is by no means accurate. What really matters in my estimation is the relationship between the scope's reticle and the erector mechanism inside the scope. Are they properly aligned, how to check that alignment and what to do if they're not exactly aligned?

I've read about and tried tall target tests, but unless the rifle, load and shooter are capable of reliably putting a 5 shot group into one hole (I'm not), there is margin for error in that test and results will be somewhat inconclusive.

I have mounted the scope to a solid mount and used a plumb bob at a distance to check erector reliability, and found errors. But is that a proper test? My mount would need to be leveled precisely in two planes ( it wasn't) , but if the scope housing that I'm using as the mounting point is not precisely aligned with the reticle and erector, how good is that? Would not any misalignment induce errors? I suspect that most scope would never pass such a test.

In my book, close is only good enough in horseshoes, hand grenades, and H-bombs, everything else is measured in thousandths of an inch. What do the experts say?