In some counties in TX they have a new law that the inside distance on the rack must be at least 13" or some such. I was out of the country for some years, got back and called the game dept in Austin - one of the game biologists called me back and explained something that I never knew:
I had assumed a 1 1/2 year buck had spikes, a 2 1/2 had 4 points, 3 1/2 had 6 and so on. He said that a 4x will most always be a 4x and that a 2 1/2 buck with 10x will have 10 or 12 but will never have 4 and a 4x will maybe become a 6x but never an 8x or 10x.
He said that the ONLY determination of age without looking at body size, teeth, etc., was to look at the inside spread. a 4x, 6x, 8x, or 10 or 12 will be at the same distance inside spread when 1 1/2, then at a larger spread at 2 1/2 and larger yet at 3 1/2. When a whitetail's rack is just outside of his ears, he is 3 1/2. When it goes 1" outside, he's 4 1/2, 2" outside, he's about 5 1/2 and so on.