Redfield peep sight 0'ing

[M39MosinGoose]

I Have a Redfield peep sight that I need help with finding the exact 0 elevation. I have no problem with the windage considering it's pretty straightforward.

So far three parts are movable, the plate with the screw holding the elevation in, the elevation screw and the button on the side. I'm not sure which one to start on to 0 it

I'll be drilling and tapping this to a already heavily sporterized Swiss K11.

 

[guntech]

As far as I know the button on the side is too quickly remove the sight or a large coarse adjustment to be finished with the dial.
I would shoot it, sighting it in at the closest distance you want, then adjust the plate to zero. That leave lots of up elevation.