I see people post taking deer, caibou, elk ect at ranges out to and over 800yds. What kind of energy requirements (minimums) are needed to kill a deer, elk, caribou, or moose? Is there a general guideline or thought on this? I see post with more mathematical equations than I can keep up with so I thought there must be some type of guidelines used to assure a clean kill at those distances. Thanks for any input, just curious as to what other feel is the minimum to take such animals.