One of the things I've recently picked up about this is that wide flat nose (WFN) hard cast bullets are preferred, and the wideness aspect is not preferred because of penetration per se, rather that the wide flat nose tends to track in a straight line through tissue once it enters the body, even when it has to smash through bone to do it. Your well-placed shot may lose effectiveness if it veers off course once inside the animal. I gather that some would argue that the bullet choice is more important than the differences between reasonably energetic cartridges: 9mm, 10mm, .357M, and .44M. I wouldn't know, personally. I'm just reporting what I've heard. I suppose semi-autos need to be well-tested with wide flat nose ammo. Revolvers will be good-to-go regardless of bullet shape, obviously.
