If you are hunting a public area, the bulls will most likely be call shy and if you approach them agressively with a bugle, they will probably go the other way. Use the bugle mainly to locate them, and then use mostly the cow call. The only time to bugle in close is if you get between the bull and his cows. If you are going in a limited draw area that doesn't get hunted hard, then the bugle might work better to bring them in. What state are you going in?