Colo Wolf. Popular opinion is that you need at least 1,800 ft lbs of energy at the strike zone to determine your effective killing range for elk. For mule deer you will need anything 24 caliber of larger with 1,200 ft lbs of energy. The 7 mag with 160 gr Noslers is an effective rifle out to about 350 to 400 yards. A 30-06 with 180 gr Noslers has an effective killing range of about 300 yards. If you are just shooting thru the rib cage, a heart lung shot, you would not need as much energy. If you are shooting thru the shoulder thats when the 1800/1200 ft lb rule comes into effect. Hopes this helps. OUT.