What is the best caliber/chambering for your self defense handgun? The debate will never end, but we can shed some light on the choices. In a semi-auto handgun your choices are going to come down to .380, 9 mm, .40, & .45. Yes, there are .32 calibers, and yes you could run out and get a .357 Sig, 10 mm, or even .38 super, but most won’t. Dig around long enough and you will narrow it to at least those four choices.
If you are a revolver kind of shooter then go buy a nice .357, carry it with confidence, and shoot .38 spcl for practice; unless you are a Matt Dillon/Wyatt Earp type, then you can lug around a .45 Colt. Or go full on Dirty Harry and carry a .44 mag. Either way, then you will learn why all those old cowboys walked with a swagger: one hip weighed 3 lbs more than the other.
Most folks now days are into semi-autos, and that is where more debate exists, so what chambering is best? That is always the question. I cannot tell you which chambering is best for you but I can tell you what chambering is best for me, and the reasons I believe it.
.380 ACP and 9 mm ammunition use the same diameter bullet. The .380 is shorter and thus can fit in a smaller handgun; shorter means less room for powder, thus is less powerful. How much less powerful is it? It depends, but probably about 30%. Due to its’ smaller size the guns that shoot it can be smaller size. If you will have trouble concealing a handgun because you are a small person or have certain dress codes or habits, and want to carry daily; a .380 is probably one of your go-to choices. It IS enough gun for self defense. The micro and pocket guns (in any caliber) will not be very accurate at longer ranges, but at the bad-word distances almost all defensive situations occur at – it will do the job if you do yours (or unless your assailant is out of the ordinary). If you want a more full size gun there is really no reason to go with a .380 unless you live in a country that does not allow 9 mm (some don’t). The difference in perceived recoil between the .380 and the 9 mm is not significant in a moderately sized gun. But the difference in power and the lower cost and higher availability and variety of ammunition is worth choosing the 9 mm.
9 mm is equivalent to .38 caliber. 9 x 19, 9 mm Luger; 9 mm Parabellum, 9 mm NATO, is all the same thing and has been around since 1902. 9 mm seems to be the caliber that sits directly at the intersection of power, comfort, and portability. It is big enough, but not too big, and just about the limit of what smaller or new shooters enjoy shooting. It has enough stopping power in almost all situations. It is small enough of a cartridge that the guns that chamber it can be almost as small as a .380 gun. And in a full size gun you can carry nearly a box of ammunition in one magazine. Continuing evolution in bullet and powder development means that 9 mm cartridges today have performance that was hard to achieve in a 9 mm even 15 years ago. There is a reason that although a lot of militaries and police departments have tried other calibers they seem to be returning to the 9 mm.
.40 caliber is the same diameter as 10mm. The 10mm was designed and championed as the .40 Super by firearms legend Jeff Cooper. It was supposed to combine the flat shooting characteristics of the 9mm, with the power exceeding the .45 or .357. It did not really catch on partly because of a disastrous launch of the Bren 10 pistol. But in 1986 there was a horrific event known as the Miami Shootout between some criminals and several FBI agents. It was pretty much a complete wreck, like it was Mr. Murphy’s (of Murphy’s law fame) birthday or something. Everything went totally sideways. Afterwards, the FBI decided they needed heavier firepower, and more of it, and went to the 10 mm cartridge. A 10 mm’s recoil is difficult for the average shooter to control and complaints of discomfort were made, so there was a special load for the FBI 10 mm cartridge created which was less powerful. A little later S&W shortened the 10 mm case, used the FBI load recipe and voila the .40 S&W was born. It is more powerful than the 9 mm (mostly) and less than the .45 or 10 mm (mostly). It is a high pressure load meaning it has a fairly uncomfortable recoil. It is larger than 9 mm so some .40 guns carry one or two less cartridges per magazine. It is more expensive to buy than 9 mm (mostly), and it can wear guns initially designed for 9 mm out faster (hypothetically). They were extremely popular several years ago, but have fallen slightly out of favor in the last few years. Ammo is slightly more expensive, at times, than a 9 mm, but it is readily available, and there are many great used and new guns available chambered for it.
The .45 ACP cartridge has been around a LONG time now. The .45 and the 9 mm have both been used in all modern wars. It is a big, and relatively speaking for the times, slow moving bullet. The differences between a 9 mm and a .45 could be crudely described as being shot with a 9 mm would be like getting hit by a passenger car at 70 mph and being blasted with a .45 would be like getting hit by a delivery truck going 55 mph. Neither sounds fun, few would volunteer to test it out, and most would never notice the difference if on the receiving end of the experiment. You won’t find many small guns in .45 and those that are will hold fewer rounds of ammunition. That being said, many people would say you don’t NEED as many rounds of ammunition (but you do, because the ones you miss with don’t count at all). There is also the argument that some military folks feel more confident in a .45 than a 9 mm. They may know something we do not. .45 caliber pistols and ammo have a reputation for being surprisingly easy to shoot with a more pleasant recoil than a .40 and some even say a 9 mm. If that is true it is likely because of the guns themselves generally being heavier (thereby absorbing more recoil), and the fact that the .45 is a lower pressure round than a lot of its’ competitors. But .45 is generally (slightly) more expensive to shoot than a 9 mm.
My primary carry gun is a 9mm. I previously owned a .40. I have a .380. I love shooting a .45. A good .357 is still on the list.
For me a 9 mm is plenty powerful enough, without being uncomfortable to shoot. It is just right. I like the feel of my gun in my hand and I can conceal it easily . Plus the ammo is plentiful and relatively cheap. Another reason is probably inertia. There are SO many people who shoot 9 mm that it becomes more popular and inexpensive simply because it is so popular…
I got rid of the .40 because of expense of ammo and lack of commonality among the group I shoot with.
I did not buy a .45 for my primary weapon due to ammo capacity of the handguns chambered for it, and lack of commonality among the group I shoot with. If 9 mm was not an option I would choose .45 without any hesitation and someday a nice pistol is going to come along in .45 and it will probably follow me home.