Josh, my hunting buddy in texas killed a buck 3 years ago that was in full velvet. We were wondering the same thing, we tagged it as a buck and took it to the check in, the game warden happened to be there and so we asked him if we had done it correctly. He said that if there is visible protruding antler, then it must be tagged as a buck. Button bucks on the other hand are not tagged as bucks, but "antlerless." He said just go by the tag, it either is antlered or antlerless.