I realize there are variables that may affect these charts but they will not vary by a very big percentage. These are pretty much inline with my hands on experience as well. These should make for interesting reading.

http://home.att.net/~sajackson/ballistics.html

http://www.scribd.com/doc/6360184/arrow-drop

1. Start by shooting a group with your bow at a target from 20 yards using your 20 yard pin.
2. Mark the center of your group.
3. Next, shoot from 40 yards , still using your 20 yard pin and aiming at the same point on the target as before.
4. Mark the center of this group.
5. Finally, measure the distance between the two marks.
6.Refer to the numbers below for your arrow speed.
Approximate Arrow Speed (fps) Spread between 20 & 40 yard groups (inches)


Just how fast would you have to shoot to drop just 6"?

Dan