For me, all I can do is guess a bit on the age. I normally use the chest and abdomen as the primary indication of age, up to about age five. That area is not pictured well. The girth of the bases of the antlers is another great clue, and the photo showing the buck's head and shoulders from the side indicates that he has pretty massive bases. You cannot assume though that the mass is all age based. It could easily be that he is genetically predisposed to have massive antlers, and at say age four, he could potentially have greater mass at the bases than an eight-year-old less gifted buck. Knurling at the bases is another indicator of age, and I see none in these photos, leaving no way to judge him based on that characteristic. Lastly, the size of the eye in relation to the skull/head and width of the muzzle, top to bottom give a quick indication of maturity, and he is clearly a mature buck base on those criteria. All that being said, I could only hazard a guess. I think he's somewhere between 5 and 8 years old. The upper number an absolute guess. I don't remember the age at which bucks normally start regression of antlers (8?/9?), and I cannot tell if he is experiencing that or not.