Simply put: With a measure of sight plain, a count of the increment markings (or detents) on his sight, and distance between the lowest and topmost marks on that same sight staff; one can do a ratio and proportion calculation and tell the original poster exactly what those values reflect in minutes, inches, miles, millimeters, zopbogs, or whatever units he/she might be interested in. In no way is it a complicated issue.
If the original poster wants to supply a little more ballistic info, we could indeed fabricate a scale on a piece of tape or metal that could be affixed to his staff and he could crank in zeros at any of his desired ranges. It was a simple question with an equally simple solution certainly not worthy of a pissing match.
Like his Pedersoli, my 45-90 has a 100 yd zero at a setting of approximately 31 minutes on its long range staff.
Have good one,
