I believe the proper measurements need to be asssesed only after a certain period of time, due to this very reason. ie shrinkage.

Not a tape measure hunter either, so don't know, but have always assumed there IS shrinkage and remember it being discussed years ago.

5 inches would be a hell of a lot. Always take photos of your heads so at least you know later if a head has been switched, Common in Africa. Has happened to me two or three times, particularly with zebra skins. Some asswipe with lots of dollars gets your good skin and you get his crap fat arsed bakkie shot POS skin ...