Rattling works best in the pre-rut and the post rut when random does are going into estrus. Bucks get compedative around this time because there aren't many does in heat so they are willing to fight for them. If yousee a big boy by himself during any rut fase though, it wouldn't hurt to try to rattle himin. During the middle of the rut I have found it not to work very well if at all because there are plenty of does in heat and the bucks arealready with does. During the main rut try a doe call, if there is abuck really dogging a doeshe will try to come to your doe call to push him to another doe, and he will follow.