ACE's post on the poor performance of the Corbon Pow'rball load (originating at Gun Zone) and the Box o' Truth tests has gotten me thinking a lot about the matter. To sum up, after penetrating cloth a .45 ACP Black Talon failed to expand, and the Powerball tends to fragment badly. For users of the .45ACP this is a pretty good round up of ammo available for the venerable 1911 et al. It would be very interesting to see these bullet types tested against one another in real world situations. The moral of the story seems to be that you can't always rely on your hollow point or whatever to do what it's supposed to do. In which case the best bet is to carry the biggest calibre you can to make the biggest hole possible.
At the moment I'd be interested to hear more about the Federal Expanding Full Metal Jacket round, a rival to Federal's own Hydra-Shok, which minimises the risk of the hollow point becoming plugged by material by the addition of a centre post.
It's certainly a confusing market for the gun-owner looking for a reliable self-defence round- and if the claims of bullet/ammunition manufacturers don't pan out then it's even more difficult to make the decision. There's a round up of ammunition performance in a number of calibres at this site and it, like a few others I've had a quick look at, rate the Federal Hydra-Shok as the most effective round to load. Seems like it wouldn't be a bad bet, although bear in mind that the usual advice is to load what your local law enforcement carries. And hope they are properly equipped.