Alan

"good guess" - well as I was close I can now claim it wasn't all a guess.

I pictured the animals I have seen, swept back crescent or not, width, cow vs bull etc and those which looked good but weren't good enough last year. I think we saw a cow similar to those horns too and they can make a nice trophy as well if cheap enough to shoot (free).

Then I used the agricultural method and estimated the width of the post and applied it to horn length and circumference.

Except that gave me totally different results so I ignore the post width method.