Wayspring...You are correct...The 25 yard zerowas based on the line of sight being being 1.5" above the center of the bore, which was much more common before the current rage of oversized objective lens...Poor ol' Jack is probably spinning like a top in his grave seeing all of the ugly monstrosities that hunters are mounting on thier rifles these days... Nothing like ruining the lines of a fine hunting rifle and making it look like something that Buck Rogers would use to shoot lunar elk......

In any case, it was only a starting point, and , as you pointed out, the only way to really know where the rifle prints at various ranges is to actually SHOOT it..