I read a book about whitetails once that said a yearling buck has only reached 10% of its potential! It also said that a 2 year old has only reached 40% of its potential. The smaller younger bucks would still be sacraficing breeding rights because even if the larger mature bucks are being shot, they are too afraid and too low on their local heiarchy to breed the does. I think that hunting mature bucks would greatly help our deer populations, and don't think that those smaller bucks will ruin the population in your area