Sorry, my bad. I am trying to do optically center.I’ve never heard of using a mirror to zero a scope. I have heard of using a mirror to optically center a scope before mounting. It’s the method I use in lieu of counting clicks.
Unless you're using windage adjustable mounts centering the crosshairs serves no purpose. Bore sight it and go shoot it.
Wow, I guess so.because they boresight their AR’s on a target 15ft across their kitchen, meaning their optic is GROSSLY maladjusted,