In a lot of regards, .380 vs 9mm is practically an irrelevant discussion. In fact, hardly anyone is actually interested in the general differences.

When a person looks for information on 9mm vs .380, what they're actually looking for is whether the reduced recoil in a .380 Pistol is worth the loss of terminal performance. Why else would you really compare the two?

And what, pray tell, is the answer? The short answer is…

It really depends.

This all starts to get complicated, but the short version of the long answer is that .380 is less powerful than 9mm and in the tiny pistols that are made for that caliber, offer very poor terminal performance compared to 9mm and as a result, you're better off with the larger bullet. However, the right .380 pistol, with the right load, is far from a peashooter and marksmanship makes most of the difference anyway up to a point.

Nebulous, isn't it? Okay, let's flesh this out a little more.

Why compare .380 vs 9mm?

A few companies make micro 1911 pistols offered in either chambering, specifically Kimber, Springfield Armory and Sig Sauer. Then there's the Glock 42, their 380 pistol, which is slightly smaller than the Glock 43 in 9mm. You might be wondering if the increase in recoil and slight increase in size (less than 20 percent) is or isn't worth it.

After all, a tiny pistol is easier to carry all day. Is the extra barrel length and faster projectile worth it?

By now, we all know that 9mm is more powerful than .380 ACP, though we'll put some numbers to it in a moment. What you might be wondering is if the loss of performance is slight enough so that .380 ACP is still worth carrying.

The answer...well, as we said. It's complicated.

So, the elephant in the room is .380 vs 9mm ballistics.

The standard 9mm load is a 115-grain to 147-grain projectile, which usually achieves something like 1150 to 950 feet per second of muzzle velocity and around 350 ft-lbs of muzzle energy from a full-size gun, and more like 875 to 1100 fps (and about 315ish ft-lbs) from a subcompact.

The standard 380 ACP load is a 85-gr to 100-gr projectile achieving around 950 to 1050 fps of muzzle velocity and around 200 ft-lbs of muzzle energy from pistol with a 3.5- to 4-inch barrel, but more like 850 fps or less from a 2.5- to 3-inch barrel and around 150 to 175 ft-lbs of energy.

.380, as you can tell, is a little more anemic. The reason, of course, is the shorter and slightly narrower case of .380 ACP (17mm in length) holds less propellant than 9x19mm (12 gr vs 13.3 gr) and as a result, the projectile is going to be slower.

As we all know, you should carry a hollow point or other expanding Ammunition for self-defense. Thing about said ammunition is that how well it works depends a lot on velocity; the slower the bullet travels, the less reliable expansion will be.

This creates a difference in terms of terminal performance.

In the real world, 380 vs 9mm favors the larger bullet, but plenty of fights have been stopped using a .380 pistol. However, 9mm has better terminal performance overall and a better track record of stopping a threat.

Most of us know the standard for ammunition testing - the FBI standard, created by their ballistic testing protocols - which is 12 to 18 inches (14 to 16 inches is ideal) in 10 percent ballistic gelatin through 5 layers of cloth and around 1.5 times expansion. A bullet that meets this standard tends to (though doesn't always!) correlate to reliable performance on a live target.

To get into every aspect of terminal performance would take a year, and this post would take about that long to read. So here's the elevator version:

Because .380 ACP is a light bullet at slow velocities, it does not meet the FBI standards very well. 9mm pistols and 9mm ammunition tends to perform better in testing and in the real world because 9x19mm holds more powder and the barrel is typically longer in 9mm pistols, meaning the projectile goes faster and is heavier.

That is exactly why .380 ACP failed the FBI ammo test in the 1980s and why .380 ACP doesn't fare too well to this day with modern ammunition, per Lucky Gunner Labs using almost the same protocol to test modern ammunition.

However, modern ammunition has improved its performance, which we'll come back around to, but has also made 9x19mm so effective that the advantage formerly enjoyed by .45 ACP, .40 S&W and .357 Magnum has almost been abrogated.

If you look at Lucky Gunner Labs testing data, what becomes clear is that .380 ACP can be effective...but you have to be very careful with your ammunition selection. And bear in mind their test gun is a Glock 42, which has a 3.25-inch barrel...not a micro pistol with a 2.5-inch barrel.

In general, 380 vs 9mm is almost no contest. 9mm is just more effective and has a better track record in the real world.

In a micro pistol, it's going to be even more dismal.

The old saw about .380 ACP is that it's just powerful enough to be barely adequate with good shot placement. Granted, 9mm is inadequate with poor shot placement. The point here is that the information that's available indicates .380 ACP is less effective in the real world, and in testing that serves as the best (though imperfect) predictor of real-world efficacy, does not acquit itself well.

But are there reasons why you might still choose a .380 over a 9mm? Well...there are a few.

There are some ways in which discussing "380 vs 9mm" favors .380 ACP, but it has little to do with the caliber itself. Instead, it has to do with the guns that chamber it.

So, to explain that, .380 ACP leaves the barrel at a slower velocity. As a result, it doesn't require the same spring rate to send the slide back into battery.

The quick explanation of that is that the faster a bullet leaves the barrel, the faster the slide of a semi-auto pistol is sent hurtling backwards on the frame. The faster the slide travels, the stiffer the recoil spring needs to be to slow it down and push it back into its resting position.

Since the recoil spring doesn't have to be as stiff - and here comes the point - the slide is easier to operate. This is important for people with weaker hands that find pulling the slide all the way back on, say, a Glock 19, to be difficult.

Which, incidentally, is all over the marketing materials for pistols like the Walter CCP 380 and Smith and Wesson M&P Shield 380 EZ.

One aspect in which the caliber itself can be advantageous is in terms of recoil. Bear in mind that recoil energy and recoil force, the sheer physical force exerted by the gun on the shooter, is not the same as felt recoil, which is what the shooter perceives; the former is the product of an equation and the latter is what you feel when you shoot a pistol.

A .380 pistol will produce half (or less) the recoil energy of a pistol of equal weight chambered in 9x19mm. Therefore, .380 vs 9mm will favor the smaller round for shooters who are recoil-sensitive.

Then there's the size aspect. The person who demands the tiniest possible gun for whatever reason - either they want the utmost in discretion or ease of carrying, or a backup gun for a pocket or ankle holster - there are just far more .380 vs 9mm guns made for the purpose.

But what if you just couldn't live with anything other than a .380, or still wanted to have one as a back-up gun or pocket pistol for carrying around the house or putting it in fanny pack or something while out for a jog?

Let's say there's a hypothetical scenario in which you had to choose .380 vs 9mm, you had to make .380 work, or you had a .380 pistol in your personal armory (for lack of a better term) and wanted to be able to rely on it to do the job of a personal protection gun.

In the broad strokes, there are three things you'd need to do.

First, make sure you have a holster for it. DUH. Especially if you're thinking of pocket carrying. Pocket carry without a holster is an accident waiting to happen. Just...don't. Not now. Not ever.

Second, train with the gun. You can get hits or you can't, and everything else is secondary. If you have a .380 pistol that you can't shoot worth a darn, then you aren't really armed are you?

Lastly, ammunition selection is crucial. Make sure you've selected an appropriate carry load. For micro pistols, select a short-barrel load that's designed to function at reduced velocities. If possible, opt for .380 ACP +P loadings. Overpressure ammunition has an increased powder charge, propelling the bullet to faster velocities, which can make penetration and expansion more reliable, which .380 ACP has traditionally been lacking for.

It isn't that .380 ACP isn't effective, because it is and can be. However, it is the case that .380, along with .38 Special (which has similar performance in standard-pressure loadings) is something of a bare minimum when it comes to calibers used for personal protection. Bigger is better, but it will work in a pinch. Most calibers smaller than .380 are dismal (with some exceptions) but larger, more powerful calibers tend to be more effective in the real world.

The bottom line? .380 works if it has to, provided the shooter is a competent marksman and with proper ammunition selection. But in the broad strokes, you would be better off with a 9mm if you can help it.