Ammo size.....confused

[JanaGB]

Anyone care to give me a quick (if there is such a thing) lesson in ammo sizes? I'm reading some posts and scratchin my head. I feel like I'll never understand!!

What I mean is.....

For example.... is 9mm larger than 40? Why is 22 smaller than 9?

I'll never get this, but I'm trying!!!

:banghead:

 

[Damon555]

9mm is listed in metric, it's a .355" bullet and the .400" (10mm) is already in inches. 9mm is not larger than a .40.

22 (.224") is a 5.56mm so has a smaller diameter than the 9mm (.355").

22 = .224"
9mm = .355"
10mm = .400"

 

[SDC]

It's simply the difference between imperial and metric; depending on where and when they were developed, used or sold, cartridges can have a metric name, an imperial name, or both. 22 Long Rifle was originally developed as a cartridge using imperial measurements, because it uses a .22" bullet, but many European users call the same cartridge the 5.6mm Long Rifle. The 9mm Luger fires a 9mm bullet, which is about .355", but you never hear about the ".355 Parabellum", or ".355 Luger", because everyone knows it by its more common metric name. 45 Auto was developed as an imperial cartridge, but when the Norwegians bought these pistols for their military, they called that cartridge the "11.43mm". There's a different history for each cartridge name, and the only way to know the hows and whys is to buy a book like "Cartridges of the World", and go through it one round at a time.

 

[JTQ]

Here is wikipedia's take.

http://en.wikipedia.org/wiki/List_of_handgun_cartridges

Here is another

http://www.operatorchan.org/z/src/PopularHandgunAmmoComparison.pdf

 

[Onmilo]

To obtain inch measurement in millimeters multiply the dimension by 25.4
i.e., .357"X25.4mm=9.0678mm
To obtain metric measurment from inch dimension divide the dimension by 25.4
i.e., 7.9mm/25.4mm=0.3110236"

25.4millimeters=1 inch.

English/American calibers are designated by no more than three digits behind the decimal and metric calibers display the primary measurement and no more than two fine designators behind the decimal so they are rounded up or down from the complete number designation and even these dimensions can be a bit confusing as they are sometimes concluded by the Land measurement of the bore and not the actual bullet diameter.

Example .25 auto (english)/ 6.35mm (metric) uses a .256"/6,5024mm diameter bullet.
Somewhere along the way, somebody decided ".25 auto/6.35mm" sounded better than ".256 auto/6.5mm"
Hope this helps.

 

[yhtomit]

I second the recommendation of "Cartridges of the World." Even for novices like me, it's a fun book to read through, and wonder at the variety in this (in the grand scope of things) obscure corner of the human world.

The posters above have hinted at but only scratched the surface on some of the oddball names, even ostensibly straightforward and numerically bound names.

timothy

 

[Zundfolge]

Then we throw shotgun gauges in there and JanaGB's head explodes (shotgun gauge is based on how many lead spheres of a given size make one lb ... so if you had a lead ball that is 1/12 lb the diameter would be the same size as 12ga).


Keep in mind that most calibers only refer to the diameter of the bullet, but not the case length and other factors.

With metric calibers its usually pretty straight forward, 9mm is also referred to as 9x19 (9mm diameter bullet on a 19mm long case) but that's only part of the story since it doesn't take into account bottle neck or tapered cases (for example a .50BMG can be expressed in metric as 12.7x99mm, but that 99mm long case is a bottle neck case that expands out from half an inch at the bullet to about 3/4" at the rim.

Some non metric calibers try to clarify things but they don't really. for example .45-70 is a .45" diameter bullet on a case that contains 70 grains of black powder. The .30-06 is a .30" bullet that went into service in 1906.

So basically don't feel bad that you're confused because a lot of it makes no sense.

 

[Remo223]

There is no "quick" lesson. There are basically 3 systems. decimal inches in diameter, and millimeters in diameter, and "gauge"(sometimes called bore). gauge is an archaic system of measuring diameter that involves constructing lead spheres and counting the number of lead spheres it takes to displace a pound of water.

but it gets more complicated than that. various systems of nomenclature will indicate powder charge, or equivalent powder charge, or cartridge length in addition to barrel/bullet diameter. it's not uncommon for one cartridge to go by several different names in different regions or countries.

 

[oneounceload]

9mm is also referred to as 9x19 (9mm diameter bullet on a 19mm long case)

So what about the 9X17, 9X18, 9X19, 9X21, 9X23, and on and on? Too many ASSume 9mm means the 9X19 or 9mm Luger - tis not always the case (literally and figuratively)

 

[hammerklavier]

And don't forget that the name of the caliber is not always accurate. A .38 and .380 are actually .35 caliber rounds.

 

[sgt127]

And, the .357 Magnum sounds like its smaller than the .38 Special, but, its not. They are both .357 in diameter. But, the .38 was named the .38 special, it sounded good. Not to be confused with the 38 S&W. Or the 38/200.

Then there are calibers like the 44.40, 30-30, 30.06 to worry about.

Cartriges of the World. Good book, well worth the money.

 

[highorder]

Cartriges of the World. Good book, well worth the money.

This.

 

[woad_yurt]

Here in the USA, lots of cartridges are named so because it sounds right, not because it's an accurate description. Someone's already mentioned .38 SPL above.

If you want some actual measurements, wade through this:

http://www.stevespages.com/page8d.htm

 

[neededausername]

Yes it gets confusing as someone pointed out a .357 is more powerful than a .38 is more powerful than a .380. Throw in rifle and shotgun and it starts to get even worse. Just think of a 7.62 x 39 vs a .460 Wby. The 7.62 sounds much more powerful than the .460, but I wouldn't go hunting big game with an SKS if I had the choice.

When I first started reading about Mosins I was confused because I thought 7.62x54R meant rimfire, not just rimmed.

It's like anything else that has a lot of technical jargon, just keep reading, go shoot whatever you can get your hands on, and you will get the hang of it.

 

[mljdeckard]

Bet you thought you would be LESS confused with the answer, didn't you?

 

[withdrawn34]

You can also use Google to quickly convert units.

For example, type the following into Google

9 mm to in

 

[Manco]

And, the .357 Magnum sounds like its smaller than the .38 Special, but, its not. They are both .357 in diameter. But, the .38 was named the .38 special, it sounded good.

Actually, it's kind of the other way around...well maybe.... .38 Special (full name is .38 Smith & Wesson Special) was based on .38 Long Colt, which in turn was the successor to .38 Short Colt. During the transition from cap & ball revolvers to metallic cartridges, the latter originally used "heeled" bullets that were the same width as the outside of the case, which was approximately .38". Although this changed at some point to non-heeled bullets with diameters closer to .36" (give or take, depending on the period), the name was kept (as was the .38" case diameter) and passed on to larger, more powerful cartridges (even with their slightly narrower bullets). I guess it wouldn't make much apparent sense to apply a smaller "caliber" number to something more powerful that is based on something weaker, right?

As for why .357 Magnum (actually .357 S&W Magnum, and based on .38 Special) was named as such, I would guess that it's because the "Magnum" part makes it sound powerful as it is, and that ".357" is not only the accurate diameter of the modern bullets (a personal preference of the inventor, perhaps?), but sounds cooler than ".38 Magnum" or ".36 Magnum".

Not to be confused with the 38 S&W. Or the 38/200.

Or even worse, .38-40 Winchester, which has .401" diameter bullets (mysteriously larger than the caliber name instead of smaller this time).

To the OP, the bottom line is that each so-called "caliber"--really the name of each type of cartridge--does not necessarily correspond to the real characteristics of the cartridge. Sometimes different characteristics are included in addition to the supposed bullet diameter, and sometimes those are obsolete or just plain inaccurate as well. And as others have pointed out, some "calibers" have names based on different units (e.g. millimeters as opposed to inches), making direct numerical comparisons meaningless.

It's all pretty fascinating (I think) once you get over the initial confusion and learn to not take the caliber names too literally. You can start by familiarizing yourself with the most popular modern cartridges for handguns (since this thread is in a handgun section) before moving on to others. You probably know what they are, and even Wikipedia's information on most of them should be accurate (not 100% but close) and complete enough to get you started without getting too overwhelmed.

 

[Manco]

You can also use Google to quickly convert units.

For example, type the following into Google

9 mm to in

That's a useful tool and helpful tip, but as a reminder to anybody reading this who is not yet familiar with the various calibers, do not take the caliber names too literally. For example, 5.7mm cartridges use .224" bullets--OK, that works out pretty well mathematically. But 5.56mm cartridges also use .224" bullets, not .219" like the math would suggest. Huh? And so do .223 cartridges, quite deceptively I might add. Why? Each caliber name has its own reasons and story behind it if anybody is interested, but the bottom line is do not trust the name!

 

[george29]

As for why .357 Magnum (actually .357 S&W Magnum, and based on .38 Special) was named as such, I would guess that it's because the "Magnum" part makes it sound powerful as it is, and that ".357" is not only the accurate diameter of the modern bullets (a personal preference of the inventor, perhaps?), but sounds cooler than ".38 Magnum" or ".36 Magnum".

Had nothing to do with cool-factor everything to do with safety.

357 was not based on the .38 special, it was based on the 38/44.

 

[Geckgo]

Lyman reloading handbook, 40 bucks and a good primer on everything cartridge related. Nice little section in there on cleaning too.

 

[suemarkp]

One other little tidbit that can be confusing. In a rifled barrel, there are two diameters -- the smaller one that a ball would fall through just kissing the rifling, and a larger one where the rifling would actually engage and bite into the bullet.

An example is "30 caliber". The bullets in many 30 caliber rifles are .308 in diameter. But the caliber nomenclature is the smaller of the two dimensions above (so a .300 ball would just fall through the barrel without engaging the rifling). So 300 Savage, 307 Winchester, 308 Winchester, 30-30, 30 carbine, and 30-06 all use .308 diameter bullets and all are "30 caliber". And so is 7.62x51.

Same with 22 caliber. The 220 Swift, 221 fireball, 222 Remington, 223 Remington, 22-250, and 22 Hornet all use .224 diameter bullets. And so is 5.56x45.

Each of the above cartridges has a different brass case. Some are very similar, or made from the others and then shortened.

 

[Silent Sam]

"357 was not based on the .38 special, it was based on the 38/44."
I think you'll have a hard time proving that, even if you meant 38-40. The .357 case has the same body and head diameters as the 38 Special case, only about 1/10" longer and uses the same bore and groove diameters and both cartridges were developed by S&W.

 

[george29]

Where did the .357 come from and why? According to Roy jinks' The History Of Smith & Wesson, it was developed from the .38-44 High Velocity to provide higher performance than possible with the .38 Special. Elmer Keith said in his own book, Sixguns, that the .357 evolved by lengthening the .38-44 HV case (which was externally identical to the .38 Special) to prevent it from being chambered in weaker .38 Special guns. He also strongly intimates that the .357's performance level was more or less equal to, not higher than, the .38-44 HV

So am I still having a hard time proving this?

 

[foghornl]

Thoroughly dazed and confused yet???? :banghead:

"But wait, there's more...."

.44Special & .44Magnum...nominal diameter of .430. the .45ACP and .45 Colt are .451

Now, the Civil War era blackpowder ".44's" used a .455 diameter lead ball

 

[JanaGB]

Um.........