Are you certain you had it with you IN THE FIELD ?
When was the last time you held it in your hand before that hunt ? Make sure it didn't fall between the car seats or in the trunk (instead of being out looking in the grass).
Sit and think what you did and where, after that last fondle.
Retrace the steps and look especially well at locations where it might have been impacted, touched, moved etc. Did you trip anywhere ? Take something out of the same pocket ? Change clothing ?
Its somewhere, keep looking, however, sit and think a bit first. It might not be where you are thinking. You can't find something if it isn't there to be found.
ChuckC