Barnes here is my two cents worth, I define a mature deer by its body and not its rack, an immature buck can have a huge rack and a mature buck can have a small one. To me a mature buck in his prime has a broad/flat back and a heavier chest than an immature buck. An immature buck has a round back and a smaller chest than a mature buck. An old buck will not only have the broad/flat back, but his back will actually droop enough to where his belly seems low, he will also get greyer in his face.

The Tazman aka Martin Price
Founder and President of
Virginia Disabled Outdoorsmen Club