On a typical 8 framed buck take your hand and put it behind the last point going off the main beam on the end fork and wrap your hand around the beam. In most cases if you can get 3 hand grips in between the end fork and the end of the main beam you have at least a 4.5 year old buck. This doesn't work on all 8 point frames (It didn't on mine) but on most of them it holds pretty true. I learned this a few years back from a P@Y measurer.