I look at it this way GR8 and there is no science here however, at 20 yards I'm dead on. At ten yards I'm an inch high so I know that 10 yards away from me or half way to the target I am an inch high.....

At 30 yards, if I'm at full draw and I'm looking down the range through a window, my 20 yard pin must have a clear path to the animal at 20 yards and at least an inch at 10 yards. I've experimented with this in my backyard and I've been successful.

What some seem to forget when looking down range in the woods is where are your other pins as far as obsticles.