Ok, here are my numbers...

20yds = 60ft
speed of sound = 1120fps

time for sound for travel 60ft = 60/1120 = .05sec.

Let's use Bill's reaction time of .05sec..
That gives the deer .1sec to hear the niose and begin to react. The arrow is already 30 ft and closing in on the deer...


Now here is my data: My videotape shows the deer dropping actually more than 18" but we'll use 18"...In slo-mo frame by frame it took seven frames to the lowest point of the drop. Each frame (and I asked an expert on cameras this) represents 1/30 sec...That says that she dropped 18" in 7/30 or .230sec

At 300fps the arrow is already half way there.

It's going to take another .1 sec for the arrow to travel another 30 ft...The doe would be 7.8" into the drop....

At 250fps the arrow has traveled only 25 ft and has another 35ft to go..it will reach her in .14sec and she'll be nearly 11" into the drop..

If you are aiming at the middle of the torso at broadside, the 250fps arrow will miss completely and the 300fps arrow will spine her at best.

At 10yds the numbers are less dramatic:

The 300fps arrow will reach the deer that is 1.8" into a drop and the 250fps arrow reaches her ar 3.4" into the drop. Both numbers can cause a wounding shot..

Now do this from a treestand and that 1.8" or 3.4" drop has an added angle to contend with...

Bottom line...nervous deer...aim a little low..I hold on the lower 1/3 of the torso..

These scenarios, of course, apply only if nothing else comes into play....and we all know that lots of other things can and do happen....