You have some great deer there Big Blue. I struggle to age the deer on this property but feel I do OK. However on a property far, far away it is impossible for me. There are many factors that tell me age here. One is antler diameter just above the burr. Using the eye which is around 4 3/4 inches circumference according to DR. Krolls "Aging And Judging Trophy Whitetails" to determine the antler diameter just above the burr works great. If it is larger than the eye here it is a solid 4 1/2 or more. Then I look at the neck, if it is very, very huge and fits into the chest and shoulders seamlessly then it is 4 1/2 or more. That particular book has pics of northern and southern bucks throughout their lifetime. I use it to age deer in pictures and found it to be easily doable and believable for the deer here.
For example using just those two criteria, the third deer pictured (picture 3) if living here would be a solid 4 1/2 and up. I don't know if those two criteria apply to Nebraska. Note; Dr. Kroll's book doesn't say to age deer just by those two criteria but I find it works for me just fine. I mean REALLY! When you only get a second or maybe three to age the deer in the brush just how many measurements can one take?
Realizing antler growth is so different in each state, it may or may not be applicable to use antler diameter to field judge age as I feel it is here.
edit- thanks Tap. Words fixed.