Thanks tazman...I appreciate your input. I can try that, it's sorta reverse of what I am doing (aligning concentric circles from the outside in towards the spot)...if I understand, I'll read it again before I go out again.
This video sorta explains what I was talking about by having the cheek weld change subtly & create a parrallax...
These shooters seem to have a different view with their hi-tec gear...as we see from the iris to the inside of the globe assembly at the muzzle...but...it's this very slight movement I was trying to explain.
Parallax errors and second ring
https://www.youtube.com/watch?v=UI0kFTDPr8w