A question I get all the time is which caliber is the best choice for personal defense. This can be a tough question to answer, especially since there is not one specific caliber that fits for every situation.
That being the case, instead of recommending a caliber I will recommend a range to stay within. The first thing to keep in mind when considering caliber is to ensure that you are carrying a caliber that is capable of stopping the threats that you are protecting yourself against. If I spend most of my time hiking in the woods, then protection against wildlife might be the specific reason behind carrying a firearm. In that case I would want to carry a caliber that is capable of stopping wildlife indigenous to that area. Example: if bear and cougar are my main concerns, I probably wouldn’t want to carry a .380 ACP since that is a small caliber that would not typically stop large animals. Instead I would probably carry something like a .357 Mag. For personal defense in close proximity, a .380 ACP could be sufficient.
The next thing to keep in mind is to ensure that you select a caliber that you are capable of being accurate with and managing the recoil from. If a smaller individual selects a large caliber and the higher felt recoil negatively impacts accuracy, the individual would have a higher probability of missing their intended target.
It is imperative to remember that it is never acceptable to accidentally injure or kill innocent persons. We are responsible for every round that we fire, up to and even after that round stops. Even if we are justified in using deadly physical force to defend our lives, if we miss that deadly threat and injure or kill an innocent person we could be charged with a crime.
My recommendation is to stay within a range of commonly used calibers. That range would be .380 ACP, 9mm, .40 S&W, .45 ACP, 38 Special, and .357 mag. These are not the only good calibers out there, however these are some of the most commonly carried calibers. It is also easier to find ammunition in these calibers which makes them a great choice to carry for personal defense.