Just wondering if people have some ideas on how much antler growth bucks do as they age. From 2 1/2 to 3 1/2 years old I've got a fair handle on it, they seem to grow by about 1/3 of their BC score. But what about from 3 1/2 to 4 1/2 y.o., and 4 1/2 to 5 1/2 y.o.? Does anyone know?

There is no single standard by how much antler growth to expect with age.

There are a variety of variables that play into antler growth including, but not limited to:

Genetics
Available food: including quality and quantity
Available Minerals
Amount of stress

So on and so forth

Bucks in agricultural regions will put on more inches of antler per year than those of regions where food is not so readily available. And even with that information, genetics plays a very big role and predicting genetic effects is, for the most part, impossible without labratory testing. You can always guess, but that's just what it is - a guess.