One formula that I saw, indicated that one needs 10lbs of energy for each lb. of body weigh. A coyote that weighs 40lbs. then at a given range one needs 400ftlb of energy to complete the job. So at what range does your bullet drop below 400ftlbs of energy. Take notice nothing is said about bullet construction or anything like that. I do not know where this idea came from but writers seem to quote this often. Is it correct? It may give one a starting point to think about.