depending on where your from, food supplies, etc. are gonna make a huge impact on antler growth and body size. you cant decide age by antler size. its like trying to define the age of a car by its tires. (ya'll know what i mean). what you will have to do when you shoot it, if you get a chance, is look at the molars of the lower jaw bone. that will be able to tell you about how old it is. beautiful deer tho. good luck! and welcome to the site!
Remington 710 .270
Smith And Wesson M&P40
Mossberg 835 Ulti-Mag 12 Ga
CVA optima Mag .50 cal. Muzzleloader
1968 Browning recurve