Talk:Caliber

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[edit] Over-simplified

The main Caliber#Firearms section of the article is way over-simplified. I intend to merge in something like:

Traditionally calibres were expressed in inches, and this is still the norm for civilian firearm calibres of US origin. However, due the the long period over which this system was used, it accumulated many complications which mean that a calibre in inches is often not simply, or not even, the same as the actual diameter of the lands. Some have suffixes with largely arbitrary meaning. For example, in the .45-70, the .45 refers to the calibre while the 70 refers to the charge of black powder (in grains) with which it was originally loaded; similarly the .30-30 had a .30" diameter and took 30 grains--but of cordite this time. And the .30-06 didn't take 6 grains, it was type approved (adopted by the U.S. Army in 1906)! Even more complicated, sometimes the "suffix" is encoded into the calibre itself, even to the extent of making it wrong. Thus the .22 WMR, .218 Bee, .22 Hornet and .223 are all actually the same diameter (which is .224", not .22"!) with the numbers varied to indicate that other aspects of these cartridges make them non-interchangeable. Even more extremely, the .38 Short, .38 Long, and .38 Special are all the same diameter, and it isn't .38", it's .357", the same as the .357 Magnum; in fact each of the smaller cartridges in this series can be safely fired in chambers meant for larger ones, but not the other way around.
With this kind of historical confusion, fortunately metric calibres are much simpler. The calibre in millimetres is simply the true diameter of the lands (or, occasionally, the bullet; we wouldn't want this too simple!), to some reasonable tolerance. If this leaves ambiguity it is clarified by following with the length of the cartridge case in millimetres. Thus we have the 7.62 x 51 mm (a NATO standard) and the 7.62 x 39 mm (a Warsaw Pact standard). Metric calibres are used for practically all military calibres (including post WW2 US ones) and most civilian calibres originating outside the US, at least recently.

But someone might like to fact check it first! Securiger 17:12, 14 Mar 2005 (UTC)

So instead of over-simplified we risk over-complicated? GraemeLeggett 09:05, 15 Mar 2005 (UTC)

"9 mm" might very well be the only metric measurement many Americans know of. — JIP | Talk 10:20, 6 May 2005 (UTC)

I very much object to the article's claim that "It is technically incorrect to say 9 mm cal.". The subsequent paragraph clearly and correctly states that caliber is not a unit of measurement, so why isn't "9 mm cal." (or "9 mm caliber") fine? Woseph 11:37, 28 May 2005 (UTC)

  • After three months of no comments or changes, I'm removing the offending sentences from the article. -- Woseph 07:36:09, 2005-08-31 (UTC)

[edit] Conventions of measurement in firearms

The author of the article, "Caliber", gives one convention for bore measurement - that is the minimum or nominal diameter measured in a barrel's bore. In a rifled barrel bore, there are two diameter dimensions - commonly referred to as groove diameter and the other nominal diameter.

Groove diameter is the maximum dimension of a bore between the bottoms of the grooves of the rifling. In direct measurement terms, this is often only intrinsic since two maximum points of groove depth may not exist because the rifling's geometry may not pose two such points in diametric opposition in the bore. Still, when a slug is upset and pushed through the bore and measured for maximum obturated diameter, it will yield "groove diameter".

Nominal diameter is the diameter of the theoretical cylinder measured at two points on the surface of the rifling's lands. The nominal bore diameter, then, is the groove diameter less twice the land height (or groove depth).

Rifled barrel manufacture takes place in one of two ways and the confusing conventions as to bore measurement arise from this.

In one means of manufacture, a mandrel bearing the dimensions of the rifling as raised ribs on a cylindrical bar in a helical pattern (the measure of the helix pitch being the "twist" or "rate" of the rifling, generally expressed as a ratio of one full turn of the helix in a given number of inches)is inserted in a tube of approximate groove diameter internally. The tube is then upset onto the mandrel, forcing the mandrel's profile into the tube. The mandrel is withdrawn and the tube is now a rifled barrel having a groove dimension more or less as the tube began and a nominal dimension more or less that of the mandrel cylinder. Commonly, this means of rifling is referred to as "hammer forging" for the impact process of hammering the tube into upset on the mandrel. This is the earliest form of rifled barrel manufacture and dates to the time when all barrels (and all tubes, for that matter)were formed by the "Damascus" process of hammer and forge welding of strips of "steel" together to form a tube around a mandrel.

In the other means of rifling, a tool is passed through a tube of nominal diameter to either cut or upset the rifling pattern into the bore. The variety of techniques to accomplish this method is great enough to be beyond the scope of this addendum.

Bottom line, both measures are diameter, rifled barrels have two "bore" diameters, and any consistency in their general reference naming is coincidental.

Respectfully submitted,

Jacksnipe

[edit] US vs British

Folks, why all the refs to "calibre" are now replaced with "caliber"? Does it mean that americal english (Mein Gott! I found this sequence of words real fun!) is now the language standard for the whole world? /BTW, the xUSSR was using british english as educational standard.../ --jno 07:53, 19 June 2006 (UTC)

Its for consistency within the article. If an article starts off with US English spelling then it is the done thing to stick with that no matter what the author's natural usage is assuming that the article is not of itself naturall BE or AE - see the MoS for more details GraemeLeggett 08:40, 19 June 2006 (UTC)
I mean another articles, like 7.62 mm caliber. --jno 11:23, 19 June 2006 (UTC)

[edit] Numbers?

Can anyone explain the origins of some of the calibers? Why, for example, is there a .22 caliber, a .357, a 7.62mm, and so on? Why did someone decide to manufacture the ammunition in these weird numbers instead of round figures?

Septegram 20:41, 24 August 2006 (UTC)

Some countries still use inches, while others have switched to SI (metric).
And now we have (7.62 mm ÷ 24.5 mm/inch ≈ .311 inch)
Then take into account that, say, a "SI based country" has purchased the license to build an ammo from "inch based country" and converts the documentation...
Add the different ideas of measuring "caliber" as internal diameter...
Moreover, read carefully for the info of "mere caliber numbers" obtained as a number of spherical bullets made of 1 pount of led... --jno 10:46, 28 August 2006 (UTC)
OK, I can see how the metric numbers are odd because they're conversions from equally-odd non-metric versions, but who on earth decided to make bullets at .311 inches diameter? Were they all based on fractions of a pound of lead?
Thanks for your help, by the way. This is something that has always baffled me. I'll go back and reread the sections you mention when I have a minute or six.
Septegram 14:56, 28 August 2006 (UTC)
Anyway, it's mostly historical issues with those "odd" caliber numbers, and the "number of spheric bullets of 1 pound of led" seem to be the simplest reason :-)
Take into account, that cartrige production is "more basic" than firearms for that cartriges! There are lots of firearms made for an existing cartriges (even for non-domestic! Fedorov's automatic rifle for captured japanese ammo, for instance), but new ammo get introduced very rare. --jno 09:05, 31 August 2006 (UTC)
This is kind of related to septegram's question, but can someone provide a list of the most common calibers, and possibly their mm equivalents? It'd be helpful for gun-ignorant people such as myself. Ailes Grises 22:21, 22 April 2007 (UTC)
A couple of comments. First, people experiment with different sizes for various reasons. They're more concerned with making a round well suited to a particular purpose than they are to having a round number. Second, the naming conventions often don't match the actual size, they're more of a marketing decision. Third, different countries use different measurements, for example the US typically uses bore size, while the UK uses groove size. For a complete list of popular calibers, there is one in the subscriber section at chuckhawks.com if you're a member there. For a list that's still being worked on, see Table of pistol and rifle cartridges by year which is unfortunately sorted by year, not by size, but tends to show measurements in metric and in inch. I added a VERY SHORT list to the article, Note that everything is rounded for simplicity. It's just the basic rifle stuff, .17 (4.4mm) up to .30 (7.62mm) Arthurrh 18:50, 1 August 2007 (UTC)

[edit] "Decimal is dropped when spoken"

The article says that the decimal point is ignored when someone says it, so that a 0.22 inch barrel is called "twenty two calibre". What do you call a cannon with a 22 inch barrel? I don't think this stupid suggestion of ignoring the decimal point should be included in an encyclopaedia. Whoever wrote it has a severe lack of common sense and they were wrong to say that the decimal point "is" ignored, since it is really just a suggestion. Huey45 03:39, 5 August 2007 (UTC)

Well I've never heard anyone anywhere ever call a 22 caliber a .22 caliber. It's just not what's done. By the way, a gun with a 22 inch diameter barrel would NOT be a 22 caliber, it'd be a 22 inch gun. It's not correct to say "1 caliber = 1 inch". Arthurrh 04:10, 5 August 2007 (UTC)
Saying "Point Twenty-Two" is considered to be a very n00b-like thing to do amongst every shooter I've ever spoken to; it's what people who are new to shooting (or learnt everything from books without any real practical experience) say. You'll notice knowledgeable shooters don't refer to a "Point Thirty-Oh Six" or a "Point Three-Oh-Three" or a "Point Two Two Three"- the "point" is only spoken when it's referring to a decimal calibre, such as "Seven Point Six Two by Fifty-One NATO", "Five Point Five Six", "Six Point Five by Fifty-Five Swedish", and so on. --Commander Zulu 10:53, 5 August 2007 (UTC)