Why is overpenetration considered bad in damaging a target? This is NOT about legal ramifications or collateral damage. I understand those concerns perfectly well and find them valid. What I do wonder about is the criticism of rounds that pass through a target, in that it is considered that not enough damage is then done. Now, if it is an expanding round and it does not do so while passing through, then yes, not enough damage is done. But take two other cases.
A non-expanding FMJ pistol round. It is not going to deform or fragment. If it stops in the body, then the wound track is going to stop with it. The deeper the penetration, all the way to pass-through, the longer the wound track. The track isn't going to get larger in diameter, the bullet doesn't deform to do so. The temporary cavity is going to be affected by velocity, so heavier and faster will get you better penetration and higher impact energies. If what you want to do is damage as much of the target as possible, then you should be reaching as deep as possible, all the way through.
An expanding pistol round. This is actually no different from FMJ in this regard. By expanding, the round deforms, creating a larger permanent cavity and 'applying the brakes'. Again, stopping in the body to prevent striking unintended targets is a good thing for other reasons. But, I don't see the "maximum energy transfer" argument for wanting the bullet to stop in the middle. Again, the deeper the wound track, the more tissue damaged. The expanding round now gives you a larger and longer wound track with full pass through. The energy transfer is seen in the displaced and destroyed tissue, not in where the bullet stops. If the bullet stops in the target, it just means it had less energy than one that passes through in the same condition.
Am I wrong in my supposition that purely for wounding potential, a bullet that both expands and penetrates completely through the target is the best option?
A non-expanding FMJ pistol round. It is not going to deform or fragment. If it stops in the body, then the wound track is going to stop with it. The deeper the penetration, all the way to pass-through, the longer the wound track. The track isn't going to get larger in diameter, the bullet doesn't deform to do so. The temporary cavity is going to be affected by velocity, so heavier and faster will get you better penetration and higher impact energies. If what you want to do is damage as much of the target as possible, then you should be reaching as deep as possible, all the way through.
An expanding pistol round. This is actually no different from FMJ in this regard. By expanding, the round deforms, creating a larger permanent cavity and 'applying the brakes'. Again, stopping in the body to prevent striking unintended targets is a good thing for other reasons. But, I don't see the "maximum energy transfer" argument for wanting the bullet to stop in the middle. Again, the deeper the wound track, the more tissue damaged. The expanding round now gives you a larger and longer wound track with full pass through. The energy transfer is seen in the displaced and destroyed tissue, not in where the bullet stops. If the bullet stops in the target, it just means it had less energy than one that passes through in the same condition.
Am I wrong in my supposition that purely for wounding potential, a bullet that both expands and penetrates completely through the target is the best option?