You are very welcome. I too found it fascinating. Enough so that I made the workbook to visualize the potential inaccuracies, make it easier to calculate them and make comparisons. It surprised me just how little off-center the eye had to be to make a measurable and significant difference on the POA, when using a scope without parallax adjustment. Hence on my rimfires I use peeps and on my centerfire long-range or target guns I use a scope with adjustable parallax. (I like Vortex.) But on one of my deer guns I use a Crossfire II. It's adequate for the rifle and I don't care if I'm off even a half inch.
Sent from my SM-G955U using Tapatalk