I agree that with handguns it's all about shot placement, not size of bullet. In fact, since we are talking about 9mm to .380, size of bullet isn't the issue since they have the same diameter. But as for the discussion in the article, it doesn't work that well because there are literally hundreds of variables when evaluating real life shootings that such a study can't account for. And since we are talking about deadly weapons, the fact that you can average the stats from across all these scenarios, including all the variables, and get similar results among all the calibers/rounds, is not only unsurprising, but scientifically expected. I don't think that study tells us what the author thinks it does. I don't think averaging the stats of a bunch of real world shootings to draw a conclusion helps me make a good decision. The fact that .380 performed as well or better than 9mm in the averages of these scenarios doesn't tell me what will be best for any particular set of circumstance I might face. My self defense scenario may not be "average". And to do that, I don't think you can just simply ignore the science of ballistics. So if you're comparing two rounds (9mm v 380) of essentially the same diameter/cross-section, that have a negligible difference in felt recoil (meaning shot placement isn't really a factor other than 380s tend to have shorter barrels and therefore shorter sight radius with which to place shots), then I can't understand not going with the round with higher mass, velocity, and energy transferred to target. In the studies I've read where the variables were controlled (which is the only way I will trust data, no offense to the study you linked), there is a significant difference between 250 ft/lbs of energy on human tissue analog and 300+ ft/lbs of energy. Based on all my reading, I have developed that 300 ft/lb threshold for me personally and will not choose a round with less. And since a 380 round with less offers no real advantage over a 9mm with more, it makes no sense at all for me to use the lesser round. If there was actually an advantage that the .380 has over other defensive rounds then I would have to consider it and make comparisons. But the .380 falls short in every ballistic category, and given modern pocket 9mm pistols, it doesn't get any real advantage in size/concealment that it used to.