[email protected], You have it correct.
The energy figures are designed to sell guns and bows. Since the velocity in the formula is squared, a little increase can make the energy figures skyrocket making a more attractive gun therefore better sales.
The number you need is momentum. The 50 cal round ball with 65 grs of powder has enough momentum to pass completely through a deer. Holes on both sides, air into the body cavity, blood on the ground and the oil light goes on.
Deer will be down easily a quickly as one shot with a 30-06.
If you were dependent on Kinetic energy to kill an animal, how in the world could you expect an arrow to be as efficient as it is?
The round ball won't shoot through the side of a truck but I don't think you'll be hunting trucks.