Hopefully this comes out clear.
This is from the Deer Hunters Almanac. One of my favorite books on hunting whitetails.
PreacherTony, I'm not sure if its important to use the lower jaw as opposed to the upper jaw or not. I found a nice wide 6 point before archery seasonlast year and the teeth on both upper and lower jaw seemed to be the same. I aged him at 3 years old.