I’m going to open up a can of worms on this topic. There is perhaps no more effective way to stir up debate than to bring up the topic of handgun calibers.
First, let’s dispel a few myths: There is no such thing as a “man stopper” or a handgun caliber that is capable a “one-shot stop.” Compared to their larger rifle caliber brethren, all handgun rounds seem puny and underpowered. That’s primarily because the handgun itself is a compromise between portability and power. The reason military forces don’t equip their soldiers with handguns as a primary weapon is because they’re just not as effective at quickly stopping an attacker as a rifle is.
Why the emphasis on size? Because when it comes to a handgun caliber you need every bit of performance you can get.
Still, there is always the trade-off of size vs. concealability and portability. Few people would recommend carrying a small pocket pistol chambered in .357 Magnum. While such guns exist, they are difficult to shoot well and usually only hold 5 rounds or less.
Neither is a soft shooting .32 ACP caliber pistol with a 20-round capacity necessarily appropriate. A handgun is always a compromise, which is why you should choose based on ergonomics and the firearm’s intended role first (home defense vs. concealed carry) and decide on a caliber second.
Things to Consider When Choosing a Handgun Caliber.
How comfortable is it to shoot in my pistol?
Most pistols are available in a variety of calibers. Once you’ve decided what model pistol you want, try shooting it in the various calibers.
Like Dave said: choose the largest caliber you can comfortably shoot.
Can I afford to practice regularly with this caliber?
Larger caliber ammo is generally more expensive than smaller caliber ammo, so you need to add this cost difference into the equation. If you choose a larger caliber such as .357 Magnum or .45 ACP make sure that you can find ammunition that is inexpensive enough to allow you to practice regularly.
Is it a “standard” caliber?
Some calibers are simply more abundant and easier to find than others. Before you buy that pistol chambered in .45 GAP or 7.62 Tokarev, consider how easy (or difficult) it is to find a box of cartridges in that caliber.
When the ammo shortage hit a few years ago we saw everything dry up, and the unusual calibers disappeared just as fast as the more common 9mm, yet these oddball cartridges were replaced on the shelves much more slowly than the more common calibers.
When it comes to a handgun, the last thing to look at is the actual performance of the round. Colonel Jeff Cooper once said about the little .25 ACP “If you must carry a .25 ACP caliber pistol, do not load it. For if you load it, you might use it. And if you shoot somebody with it, and they find out about it, they’re likely to be very upset with you.”
While a gun chambered in .25 ACP beats the heck out of not having a gun at all, it’s simply not adequate at stopping a determined attacker. A .22 Long Rifle may meet all of our criteria listed above, being cheap, comfortable, and abundant, yet it too lacks adequate stopping power.
For most handguns .380 ACP should generally be the minimum caliber you choose. It seems like every firearm manufacturer is producing small .380 pocket pistols these days, although if you can comfortably conceal and shoot a larger caliber handgun, bigger is always better.
If it meets the criteria listed above and you can accurately shoot it, choose a pistol chambered in .45 ACP, .40 S&W, or .357 Magnum for a revolver.
Despite what anyone tells you, there is no magic number, no special caliber that reliably stops a determined attacker. Find a pistol that fits you and your needs, whether for concealed carry or home defense, and then get it in the largest caliber you can comfortably shoot.
Don’t worry about ammunition capacity; instead practice and focus on getting accurate shots.