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What "is" .380?

27K views 25 replies 17 participants last post by  HotGuns 
#1 ·
What does .380 stand for? It has a period in front, so I'm assuming it's the measurement, but it's obviously not a .38, so what's the deal? I tried a few searches on here for an answer but came up empty-handed. I also know the obvious, 9x17, and it's the same diameter as a .38 cartridge? Is that right?
 
#2 ·
Generally, a number like .380, 9mm, .45, .22 refers to the diameter of the bullet in the cartridge. So, yes, a .380 and a .38 are the same diameter, but are obviously different cartridges. The 9mm and .357 bullets are the same diameter as the .380 and .38. The numbers are occasionally changed (as in .357) to differentiate between cartridges better.

In a number like 9x17, the second number refers to the length of the cartridge, as in 7.62x39.

Rifle cartridges are a little more complicated and the numbers more frequently mean different things. 30.06 is a 30 caliber bullet and the cartridge was designed in '06. 30-30 is a 30 cal that orginally was loaded with 30 grains of black powder.

As a general rule, though, the numbers refers to the diameter of the bullet.
 
#3 ·
I understand all that, but why ".380"? The same with .357...I wonder exactly what the numbers mean. I guess the "0" in .380 just means that it's a shorter cartridge? Is there really no significant meaning to it? Because drop the "0", and it's a .38. So, you've got a regular .38 which is 38/100 of an inch in diameter, then the .380 which is the same diameter, but the "0" means.... :blink:
 
#4 ·
Numerically, obviously, there is no significance to the "0". IIRC, it is one of those differences that was added just to differentiate it from the .38. Others like .45ACP and .45LC change the name instead of the number.
 
#5 ·
The .380 has the 0 vs. the .38 to differentiate between the pistol cartridge and the revolver cartridge. It is actually .380 ACP (Automatic Colt Pistol) which was developed for the semi-automatic. The bullet is .357 but the shell casing itself is .380. All of it is just a naming convention developed by a marketing manager.

When you go to the store and ask for 9mm you normally mean a 9x19 cartridge rather than a 9x18 or 9x17. Don't get your panties in a wad over what they mean, just be sure your bullets and gun match.
 
#7 ·
So, it is made up -- thanks for the replies -- As I was out today, I was thinking about it the whole time...where on earth does the 0 fit in! :smile:
 
#13 ·
The 9mm and 380 ACP both use .355 jacketed bullets (usually .356 for lead) while the 38 special / 357 mag use .357 jacketed bullets (.358 for lead). I've seen the 38 Super and 357 Sig listed with both .355 & .356 jacketed bullets.

Hoss
 
#15 ·
No the cases are completely different and it is not safe to shoot a calibre in a gun not designed for it.the .38 spc case is .379 wide and the .380 case is only.374 among other things
 
#16 ·
You could drive yourself crazy thinking too hard about how cartridges are named. Just ask around and look up things on the internet (from reputable sources of course) and eventually you'll know most of them. I tried to explain what the different cartridge names and applications were to a complete newbie customer once; it wasn't fun. He wanted to know what had taken me 10+ years of experience to figure out in one conversation. :blink:
 
#17 ·
To the original poster. The answer is.....marketing. They probably wanted to cash in on some of the .38's fame. Last year Winchester came out with the ".325wsm" . The bullet is actually .323 in diameter but 325 sounds cooler. Also....270 win=.277 280 rem=.284 .38 spl=.357 and so on and so on....
 
#21 ·
ZERO -- a brief history of nothing.

Generally thought to first be scripted to represent zero by the Olmecs, who were probably the ancestors of the Mayans and lived approx 1200BC to 400BC.

Chinese, Indians and other mid Eastern cultures understood zero and even used negative numbers at times but usually used a blank space to represent it. Before them the Greeks and others of a more philosophical nature argued how anything could represent nothing.

More beer.
 
#23 ·
The Taylor Knockout formula is one way to compare the power of different cartridges. Here's the forumla: Bullet Weight (in grains) multiplied by Calibre (in inches) multiplied by Velocity (in fps) divided by 7000 = TKO rating. The bigger the rating the more powerful the cartridge.

Also, buy yourself a copy of Modern Reloading by Richard Lee. The book will cover almost all the different bullets and cartridges with detailed information about the bullet sizes, weights and velocities with various loadings.

Between the Taylor forumla and the Modern Reloading book you can easily compare and answer questions you'll have about different calibers and loadings and what they can and can't do.
 
#26 ·
One thing that I havent seen mentioned is the bullet weight that is generally used for the .380 is only 90 grains.

Although the .380 uses .355 bullets like the 9mm and a host of others, the 90 grain bullet is about the heaviest that can be used because of the short case and the limited powder capability.

Its the 90 grain bullet that travels not so fast that make the .380 a marginal defense round...as the bullet simply doesnt have the ballistic coefficient or the weight to be a great fight stopper. There are some newer loadings that make the .380 a better round that it originally was though, they mostly use a lighter bullet traveling much faster.

Nowadays, some of the newer 9mm's arent much bigger than a .380, so if you need a personal defense gun, the 9mm makes more sense.
 
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