As a trauma surgeon and a tactical medical specialist, I am often asked by law enforcement officers what caliber and type of handgun ammunition offers the most stopping power. I can’t answer that question. Let me explain why.
The ammunition most commonly carried by law enforcement officers is a hollow-point configuration or expanding full metal jacket bullet, typically in one of five calibers, including .38/.357, 9mm, .357 SIG, .40 S&W, and .45 ACP. Other calibers are used in some departments. But for the sake of this discussion, let’s stick with the most common rounds. These handgun rounds perform very differently based on a number of key factors that I’d like to discuss.
At most agencies it is typical for either the rangemaster or lead firearms trainer to choose specific ammunition (caliber and/or bullet type) based on the results of ammunition being run through a series of ballistic tests, most commonly the FBI’s ballistic laboratory testing. Marketing by ammunition companies also influences how agencies choose the specific ammunition for front line officers to carry.
Unfortunately, the information that agencies are using to choose the ammo for their officers is generally based on hype as well as the flawed standardized testing using ballistic gel and measurements of the depth of penetration into ballistic gel, degree of bullet expansion, and other factors. Usually, actual data on human body wound ballistics is not available to agencies when they are choosing ammo for their officers.
What is most unfortunate is that the testing of modern bullets does not give a complete picture of what a particular ammunition configuration will do in the human body to incapacitate it in a timely fashion, in other words, stopping power. The testing results “infer” or “simulate” what is believed to happen in the human body, but I can tell you that from my experience operating on gunshot patients that this just is not the case.
So back to the question at hand about determining stopping power. If you are expecting me to tell you which brand and which bullet caliber and type to use for the best or most reliable stopping power, you are going to be disappointed. But I will tell you about the factors that determine stopping power.