If you want a particular "age structure" then it would matter which bucks you killed.
I think in a very short time the age structure would take care of it's self.
Your killing less bucks more will get older. The hunter would be less likely to shoot young deer if he knew a BB would be considered a buck.
He might not shoot that 4 pt in bow season knowing he wouldn't be able to shoot abuck during gun, but if he wanted to he could.