RE: settingmy 20 yard pibn and shooting under 20 yards
I would just leave it be and as Greg has mentioned ,you most likely would only be out 1" at that distance ,and you can certainly compensate for that . Most hunter's start at 20yrds and go up from there . You'll be just fine .
As Greg say's step off 10 trds and see just how high you may be ,you may not even need to compensate from that range .
nubo