We usually break the length down into two measurements.
1. The distance from the base to the intersection of the prong. (we call this the "to the prong" measurement or "TP")
2. The distance from the intersection of the prong to the tip of the horn. (we call this the "past the prong" measurement or "PP")
This will make it easier to handle rather than trying to judge the length of the entire horn at once.
The TP will usually range from 4 to 8 inches on most bucks with the average on a mature buck being around 6 inches.
A pronghorn's ear will range from 5 to 8 inches long.
We use the ear and then guess the TP based on that in the field. If the TP is about as long as the ear on an AZ buck in Unit 10, then the TP will usually be around 7 inches.
For the PP, my Dad came up with a trick a long time ago where we try to visualize putting our hands on the buck's horns and placing our thumb at the intersection of the prong. We then try to reach to the tip of the horn, around the outer curve, with our middle finger. To do this you'll need to measure that distance of your hand with a ruler and remember it.
The only problem with this method is that you need to practice actually putting your hands on real sets of horns and trying to reach for the tip of the horn. Once you've done that enough times you can usually guess how much is either left over or how much past the horn tip you've reached. And either add or subtract the difference.
This is all explained a lot better in our field judging DVD.
I hope I haven't confused you too much.
Also, I just posted Field Judging Poll #3 on our website. Check it out!
