Somehow, some bullets, notably the Partitions, manage to blow the bejabbers out of a critter's innards, but still usually manage to poke an exit hole, which is preferable to me because it tends to leave more sign on the ground, especially at the place where said critter was standing at the shot or rather just behind. It can take a few seconds for blood to leak out, especially if the hit is at or above the curve of the body, so a little evidence at the scene of the crime is very helpful.
"Energy" is a poor measure of killing power, though a popular one. What matters is tissue destruction, and the two may not be proportional.
