That is awesome! And a darn good shot basically free hand at that range!
My Dad has also done all his hunting since before I have been able to hunt (I am 51yrs) with his old Remington 760 feather weight pump 30-06
Mule Deer in the cotton patch... Being from the South in "cotton country".... That is the last place I would expect to see a mule deer. Great buck and congrats to your Dad.