I have never killed anything but steel with a Berger bullet, so I am no authority on how they work on critters. But I do like exit holes in critters. I think they tend help with blood trails and two holes in the chest of critter is more likely to create a bilateral pneumothorax,or deflation of both lungs.
Having said this,using a 225 grain Nosler partition led to a long tracking job on a 170 pound whitetail buck,and I can promise you it had an exit wound.
So I think really tough bullets can be slow killers if they don't do enough internal damage. I have also seen relatively fragile bullets fragment on the surface and fail to reach the vitals,in these cases quick follow up shots saved the day.
It seems to me that the bullet which expands rapidly and gives you penetration well into the vitals is the way to go,but there are lots of bullets that do that well enough. Now days it's hard to pick a bad one.
Partitions aren't actually particularly tough bullets - they've got a very soft nose and tend to drop a lot of fragments.
The reality is that ANY bullet can leave you tracking, because barring a CNS hit there's nothing you can do to ensure the animal drops in place. Even breaking both shoulders is no guarantee - wild animals have insane pain and shock tolerance sometimes.
Having a massive blood trail is a good start to finding the animal though.
