Something that you rarely hear discussed about the walkback method is that the shooter MUST hold the bow in the same vertical plane for all distances!!!
If you have a level on your sight and it is set up correctly......use it or the results can give you a false reading
There are some opinions that the w/b method is a waste of time. I say try it and see if your scores improve. What do you have to lose????
You'll need a target butt that will give you 3-5 feet of vertical drop.
Shoot a group of 5-6 arrows at a dot 2 inches in diameter at 20 yds. Adjust your sight until you are hitting dead center. Disregard any erratic shots. Shoot again to check your sight. Don't forget to use your level!! Use a plumb line (homemade is OK) and draw a line down the target/butt that corresponds to the plumb line from the center of your group.
Walkback 10 yards and use your 20yd pin, aim at the center of the bullseye and shoot 5-6 good shots. Shoot again if you need to get a better group. DO NOT ADJUST YOUR SIGHT. Mark the center of your group.
Repeat this at 10 yards farther back and repeat until you reach a distance where you can no longer shoot a good group (3-5 inches).
It is possible that you will see a pattern represented by one of the colored star patterns on the below diagram.
Follow the instructions on the diagram. You should repeat this procedure periodically to ensure maximum accuracy.
Your 20yd pin must be set PERFECTLY!!! If it is not perfect your arrows will progressively hit farther to one side as you increase the distance giving a false centershot reading.