The book first analyzes the physiological aspects of incapacitating a person with a firearm. "Incapacitation" is defined as "the inability to perform hostile acts, whether unarmed or armed with a firearm or contact weapon." This analysis encompasses mechanisms of collapse, a neurologist's view of "stopping power," Hatcher's theory of relative stopping power, and the Relative Incapacitation Index. The book then describes the state-of-the-art methodology used by the Southwestern Institute of Forensic Sciences to test the stopping power of a new or proposed round of ammunition. The Federal Bureau of Investigation methodology is then assessed. The core of the book presents the results of the authors' analyses of ammunition performance in actual street shootouts combined with gelatin tests. The results predict the stopping power of specific loads in calibers from .380 Auto to .45 ACP as well as such specialty rounds as the Glaser Safety Slug, Federal Hydra-Shok, MagSafe, and others. Illustrative photographs, figures, and appended supplementary data and information