Caliber measurement question


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Old 02-02-2009, 08:00 PM   #1
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Default Caliber measurement question

I have a few questions mainly about the sizes considering when it comes to guns, it's what I am most confused about.

When it's measured in Millimeters, that tells you the diameter, correct?

Now when it's measured with the .380,.357 or .45, what is that a measurement of and what unit is it in?

What's the difference between these two types of measurements?

Also I am confused with some of the endings of the calibers, like for example, .380 ACP and many other things like that.

Also is the 9mm kind of like a standard?

I need an education in bullets!

Thanks

John



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Old 02-02-2009, 09:07 PM   #2
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Basically, the number is always the diameter of the bullet. .380, .45 are in inches, 9mm, 10mm are in the metric system. Simple as that. Some calibers have several "names", .380 for example is also known as "9mm short", "9X17mm" and so on. It has the same diameter as a regular 9mm bullet (AKA 9mm Luger, 9x19mm) but it's a couple of milimeters shorter (the casing is shorter).

Here's a Wikipedia article with some basic bullet caliber info: Caliber - Wikipedia, the free encyclopedia



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Old 02-03-2009, 12:32 AM   #3
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most european ammo is listed by bullet diameter then the cartridge case lenght. the cartridge we call the 9mm is actually a 9x19mm. it the u.s. old cartridge were in inch measurements of the bullet first, then the black powder charge, then the bullet weight, example 45-70-500. 45 caliber by inches, 70 grains of black powder, and a 500 grain bullet.then about 1900 there was an abundance of cartridges in the u.s. and imaginitive names were thought up. 30-06= 30 caliber invented in 1906, 250-3000? =250 bore diameter and the bullet speed of 3000 fps.,just to name a few. then there are the cartridge name that name their round from the bore diameter (270 winchester) while its groove diameter is actually .277".it gets more confusing.any good website will give the cartridge dimentions.and any good website will convert millimeter to inch.hope this helps if you still need help just pm me.

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Old 02-03-2009, 12:10 PM   #4
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Quote:
Originally Posted by laxexquis View Post
I have a few questions mainly about the sizes considering when it comes to guns, it's what I am most confused about.

When it's measured in Millimeters, that tells you the diameter, correct?

Now when it's measured with the .380,.357 or .45, what is that a measurement of and what unit is it in?

What's the difference between these two types of measurements?

Also I am confused with some of the endings of the calibers, like for example, .380 ACP and many other things like that.

Also is the 9mm kind of like a standard?

I need an education in bullets!

Thanks

John
The numeric "size" of a bullet is DICTATED by the Manufacturer of that cartridge. PERIOD. For example: a 44 MAGNUM is really a 44 Remington Magnum and the bullet diameter is .429" which is the same for a 44 Special. But the cartridge length determines its designation. This is true with 38 Special and the .357 Magnum.

A 45 Colt also known as : (45LC) is not a 45 ACP which isn't a 454 Casull which isn't a 460 Smith & Wesson. However, they all share the same bullet diameter which is .451" Again, it's designation is set by the cartridge MANUFACTURER for a particular pistol application.

I know this is confising... and it gets worse. For example: 9mm. It "could" be 9mm Luger, 9mm Makarov, 9mm Kurtz, 9mm Largo, 9x17mm, 9x18mm, 380 ACP, 9mm Browning, 9mm Parabellum, ETC. All of which are .355" diameter bullets with varying cartridge lengths... per the Mfg.

I hope this un-coufuses you a little. But after awhile you get used to the designations! REALLY!
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Old 02-03-2009, 12:20 PM   #5
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Here is an Excellent and detailed explaination:

Google Image Result for http://www.sff.net/people/sanders/ammo.jpg

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Old 02-03-2009, 01:41 PM   #6
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The dimensions of a cartridge are set by the inventor. Generally the inventor is a cartridge/gun manufacturer. .44 Smith and Wesson special. .44 Remington Magnum. .45 Colt (commonly but incorrectly called the Long Colt). The numeral designation may or may not have anything to do with the bullet diameter.
The .38 Smith and Wesson special was invented many years ago and .38 "sounded" good even though the bullet was .358 diameter. When the .38 special was elongated and made more powerful, it was called the .357 Magnum even though it, too used .358 diameter bullets. The .357 referred to the groove diameter of the barrel.
When naming cartridges, sometimes the groove diameter is used, sometimes the land diameter is used. The groove diameter is generally .001" larger than the land diameter.
Sometimes the name is a play on the designation of an earlier cartridge. The .38 Super is a hot loaded .38 ACP. The external dimensions are the same, but the pressures are very different.
The .38 Short Colt used a bullet with a .374-.375" diameter in an arrangement similar to a .22 LR (the bullet is the same diameter as the case, called outside lubricatred). This was lengthened and called the .38 Long Colt that used a .358 diameter bullet enclosed in the case (called inside lubricated). The narrowing of the bullet diameter was a result of putting the bullet inside the case. This was again lengthened and called the .38 special even though it still used the .358 diameter bullet. The .38 spl was lengthened and called the .357 Magnum. This was a more accurate representation of diameter but the older, shorter cartridges could still be fired in a revolver chambered in .357. Of course the .357 Maximum came out which took the Magnum term to a never seen before level.
The .44-40 was a .44 caliber cartridge with 40 grains of black powder. It did not actually use a .44 diameter bullet, it used a .427 bullet. The .44 special used a larger .429 bullet but still was not a .44. The .44 Magnum was a lengthed .44 Special and still used a .429 bullet.
To confuse things even more the .38-40 did not use anything close to a .38 caliber bullet, it used a .401 or .40 caliber bullet. It probably played on the public's recognition of the .38 name.

Metric designations generally refer to bullet diameter X case length, both in millimeters. 9 X 19, 5.56 X 45, 7.62 X 39, 7.62 X 51 etc.

Europeans will throw an "R" at the end to identify it as a rimmed cartridge. Some "R" cartridges have rimless sisters. 7 X 57R is the rimmed version of the 7 X 57 (7mm Mauser).

This could go on for days as there are more exceptions than there are rules.

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Old 02-03-2009, 04:07 PM   #7
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Ok,

Now I understand it.

Is 9mm a good choice considering how common it is and easy to come by?

Now I see how technically a 9mm is also a .380, but a 9x17 is called .380 and a 9x19 is called a 9mm.

I am seriously considering the Walther PPK which is manufactured by Smith and Wesson.

I am going to take a trip to my local gun shop/shooting range and check things out.

What do you think about the PPK?

Also, to get this straight, when you cock the gun, it puts the first bullet in the chamber and once the first bullet is in the chamber, the rest come in automatically when firing? And if it is a traditional DA/SA you can either pull the trigger or pull back the hammer and then pull the trigger, right?

Thanks
John

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Old 02-04-2009, 01:52 AM   #8
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Some cartridges are measured on the grove diameter. Like lazeronni and his 7.82 warbird and all others. Just to frig with your head some more.

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Old 02-04-2009, 12:07 PM   #9
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Good responses! You guys cleared up many of the questions I had.

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Old 02-04-2009, 12:11 PM   #10
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Quote:
Originally Posted by laxexquis View Post
Ok,

Now I understand it.

Is 9mm a good choice considering how common it is and easy to come by?

Now I see how technically a 9mm is also a .380, but a 9x17 is called .380 and a 9x19 is called a 9mm.

I am seriously considering the Walther PPK which is manufactured by Smith and Wesson.

I am going to take a trip to my local gun shop/shooting range and check things out.

What do you think about the PPK?

Also, to get this straight, when you cock the gun, it puts the first bullet in the chamber and once the first bullet is in the chamber, the rest come in automatically when firing? And if it is a traditional DA/SA you can either pull the trigger or pull back the hammer and then pull the trigger, right?

Thanks
John
There'snothing wrong with a Walther PPK. However, there are a lot of choices out there so look around and try several pistols. You may find another brand and possibly another caliber may suit you better. No doubt 9mm is the most common, but that doesn't make it the best choice! I don't own a 9mm by choice. My preference is .40 S&W and 45ACP in autoloaders, and .357 in revolvers.


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