.380 VS. 9mm for Self-Defense
The reason anyone tries to decide between .380 vs 9mm for self-defense is largely due to a concern with concealability vs potency of the ammunition. In other words, is the tradeoff of a weaker round worth it in terms of ease of carrying?
The answer? Well...isn't simple. Ultimately, the importance of caliber has been overblown to a degree; with quality ammunition and good marksmanship, .380 is very effective. On the other hand, plenty of micro 9mm pistols are available that are barely any less concealable than many .380 pistols.
The origins of .380 vs 9mm are a quite different, though they occurred close to the same time.
The 9mm, or more accurately 9x19mm Parabellum, was designed by Georg Luger in 1902 at the request of the German military, who wanted a larger round in the service pistol that Luger had designed for them. The original cartridge was a .30 caliber pistol bullet (though at an impressive velocity) in the DWM Parabellum pistol, which – of course – was commonly referred to as a "Luger."
It would later be adopted by...most militaries and police forces across the entire globe.
John Browning designed the .380 ACP caliber in 1908, expressly for self-defense purposes. ACP stands for Automatic Colt Pistol, as Browning worked for Colt at the time. Browning designed a number of small, concealable pistols that could be carried discreetly in a pocket or holster in concealment, and several cartridges for use in those pistols including .25 ACP, .32 ACP, .38 ACP, .380 ACP and, of course, .45 ACP, which was more for a service pistol role.
.380 ACP was a moderate round of moderate size, easy on the shooter but also small enough for use in an easily concealable pistol.
.380 VS. 9mm for Self-Defense
.380 vs 9mm ballistics...well, aren't really close. 9mm is faster, and hits harder, and is generally held to be more effective...though it does produce more recoil in a pistol of equal size.
The typical .380 ACP load is a 90-grain projectile, with muzzle velocity somewhere between 900 to 1000 feet per second, and around 180 to 230 foot-pounds of energy. Granted, there is a lot of variation depending on the loading, but that's what garden variety .380 is like.
Garden variety 9mm, on the other hand, is a 115-grain projectile that travels at about 1130 to 1150 feet per second from the muzzle, with about 320 to 350 ft-lbs of energy.
The reason, of course, is that 9x19mm has a longer case, which holds more powder and therefore propels the bullet to faster velocities.
Recoil...is a funny subject. Felt recoil is subjective, but recoil energy – the sheer physical energy sent back into the shooter from the gunshot – is calculable and thus quantifiable. It won't tell you what it feels like, but gives you a rough idea of the difference between two cartridges when you calculate recoil force from a gun of the same weight.
In a pistol of the same weight, .380 ACP produces roughly half the recoil force of 9x19mm Parabellum. So .380 ACP definitely kicks less when everything is equal. However...everything is not necessarily equal.
Another part of the .380 vs 9mm debate concerns ammunition performance. Many .380 pistols are made with very short barrels, usually shorter than 3 inches whereas most 9mm pistols have a 3-inch barrel or longer. The longer the barrel, the greater the velocity the bullet achieves when leaving the barrel. Since hollow point ammunition is velocity-based – meaning that it needs a minimum speed to expand in the target – slower bullets tend to fare poorly.
Since .380 ACP is already a slow round, that means ammunition selection is critical. But know, too, that – again - .380 ACP has proven to be effective in real-life defense situations IF the shooter chooses a quality bullet and does their job as a marksman.
.380 VS 9mm Pistols
As a general rule, .380 vs 9mm pistols tends to favor .380 in terms of easiest to carry and conceal. There are a lot of tiny .380 pistols, which means they are very easy to conceal and carry every day. Some people favor ease of carry above all other things; a gun you can easily keep on you is one you likely WILL keep on you, after all. That's why a comfortable, and effective, concealed carry holster is so important.
However, others favor a balance of efficacy and ease of carrying. Therefore, they'll dress around a larger gun because they know they will shoot it well and there's less of a chance of ammunition failure.
In previous eras, this was a real concern. Prior to the late 1990s, many 9mm pistols weren't very concealable. Today, the market is littered with subcompact 9mm pistols like the S&W Shield 9mm, Ruger LC9, Glock 43, Sig P938 and many more, that are slim, light, and very easily concealed in a holster.
The 9mm caliber is irrefutably more powerful and outperforms the .380, but the .380ACP pistols tend to be a bit easier to shoot and more concealable. Try both and get to see what works for you. The most important aspect is finding a gun that you can comfortably and efficiently use for self-defense when the need arises. Ultimately, your skill as a shooter matters more than mere caliber.