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Why is a gun caliber a gun caliber?


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Sensei_101 #21 Posted Apr 23 2016 - 18:05

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Sometimes the caliber labeled isn't the actual caliber just to protect people from themselves.

 

In the black power days a very common pistol round was a .35; however, when modern smokeless power was introduced the guns were still .35 caliber but labeled .38 caliber to keep people from loading the new round into old guns and hurting themselves.

 

So a .38 round is actually  .35 caliber, or 8.89 mm, basically the more familiar 9mm round.

 

Note that two different development tracks arrived at basically the same place independently which, to answer the OP's question, rounds are the size they are because they work, given the desired ballistics etc.



zloykrolik #22 Posted Apr 23 2016 - 18:24

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View PostSavage281, on Apr 23 2016 - 07:46, said:

 

American guns have always been measured in mm. It is the Brits who measure in inches.

 

Uh,M2 4.2" Mortar, M7 3" Gun and M1 8" Howitzer. US used both Standard and Metric in ordinance.

Edited by zloykrolik, Apr 23 2016 - 18:30.


Wailwulf #23 Posted Apr 23 2016 - 18:26

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View PostCrucis, on Apr 23 2016 - 08:01, said:

 

 

It's not "illogical".  It's just a different logic.  As for being stubborn, too bad.   I'm not going to cave in to a bunch of people whose only argument is that "the rest of the world does it".  That's nothing but a lemmings argument.  You can jump off a cliff like the rest of the proverbial lemmings.  I choose not to do so.

 

 

 

Metric is in base 10, meaning the differences of measurement units is either a division or multiplyer of 10. 1,000 => 100 => 10 => 0.1 => 0.01 => 0.001

 

Standard is more of a random  number 1 Mile = 1760 yards = 5280 Feet = 63360 inches

 

Schools in the USA royally screwed up when trying to teach Metric in the Seventies, as all instruction was based on converting Metric to Imperial and back again.  What the program should have focused on was just Metric, measuring things in metric only, dont care about the Standard equivalent, just move the decimal point when changing units.


Edited by Wailwulf, Apr 23 2016 - 18:28.


zloykrolik #24 Posted Apr 23 2016 - 18:34

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Metric is useful in certain areas, and Standard/Imperial in others.

 

Try to accurately measure a 1/3 of a meter. 1/3 of a yard is easy. 

 

Oh, a caliber is either a measurement of the diameter of the bore of a gun or canon or it is the length of the barrel of a canon measured in multiple of the bore. Example a .45 cal pistol is 45 hundredths of an inch in diameter, 9mm is 9mm in diameter. For canons: the 7.5cm KwK 42 L/70 gun on the Panther has a barrel that is 70 x 75mm or 5250mm (5.25 Meters) in length. The L/70 is the caliber in the gun description. This is also commonly used in naval gun descriptions.


Edited by zloykrolik, Apr 23 2016 - 18:42.


Captain_Rex33 #25 Posted Apr 23 2016 - 18:44

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metric is also applicatable in physics problems whereas with imperial you need to convert a bunch of random non-base 10 numbers just to get correct values, the fact we don't even teach metric concurrently with imperial is stupid, and the argument that we should switch to metric because the rest of the world uses it is backwards, we need to switch to it for the SAME reason they did, not because they did, that reason being that it's actually logical and not random numbers that have nothing to do with each other... 1 mile > 1,760 yards > 5,280 feet > 63360 does not make nearly as much sense as 1km > 1000m > 100,000cm > 1,000,000mm.

 

also why don't we use Celsius were 100 degrees is boiling not "pretty warm". it just makes no sense



RC_1140 #26 Posted Apr 23 2016 - 19:12

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View PostCrucis, on Apr 23 2016 - 07:17, said:

 

Honestly, this annoys me no end.  American guns in the period covered by the game were measured inches, not mm.  Why not use both in descriptions?  I don't need to be "taught" the metric system.  All this "teaching" does is make the developers look annoying and pedantic.

 

 

Look at shell names, I seem to remember some are in inches. Can't remember for sure though and I'm on my iPad. 



Anlushac11 #27 Posted Apr 23 2016 - 19:46

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most US road signs now list Imperial and metric. US is slowly going metric but it is going slowly.

 

Caliber is a term used to describe the internal diameter of a round or cylindrical body, especially a hollow cylinder.

 

"The Calibres de France ("French calibers") was a system of standardization of cannons in France, established by King Francis I of France from about 1525.[1] The objective was to simplify and codify cannonry, in order to facilitate production"

 

From the same people that brought you the metric system

 

EDIT: "1560s, "degree of merit or importance," a figurative use from Middle French calibre (late 15c.), apparently ultimately from Arabic qalib "a mold for casting." Arabic also used the word in the sense "mold for casting bullets," which is the oldest literal meaning in English. Meaning "inside diameter of a gun barrel" is attested from 1580s."


Edited by Anlushac11, Apr 23 2016 - 19:49.


KaiserWilhelmShatner #28 Posted Apr 23 2016 - 20:01

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I personally believe that all guns bores should be measured in moots and shells be measured in stones.

stalkervision #29 Posted Apr 23 2016 - 20:14

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View PostAnlushac11, on Apr 23 2016 - 13:46, said:

most US road signs now list Imperial and metric. US is slowly going metric but it is going slowly.

 

Caliber is a term used to describe the internal diameter of a round or cylindrical body, especially a hollow cylinder.

 

"The Calibres de France ("French calibers") was a system of standardization of cannons in France, established by King Francis I of France from about 1525.[1] The objective was to simplify and codify cannonry, in order to facilitate production"

 

From the same people that brought you the metric system

 

EDIT: "1560s, "degree of merit or importance," a figurative use from Middle French calibre (late 15c.), apparently ultimately from Arabic qalib "a mold for casting." Arabic also used the word in the sense "mold for casting bullets," which is the oldest literal meaning in English. Meaning "inside diameter of a gun barrel" is attested from 1580s."

 

Didn't Jimmy Carter propose a switch to the metric system in the USA?



Walter_Sobchak #30 Posted Apr 23 2016 - 21:22

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View PostZXrage, on Apr 23 2016 - 10:05, said:

It's a vague question I know, but hear me out.

 

I never understood why the caliber of the gun on some tanks are the way they are. Why is it 105mm? Why couldn't it be 104 or 106? Does geometry have a role in designating caliber of the gun? I'm curious.

 

I think that is a totally valid question, I've thought of it myself from time to time.  I don't think there is a single answer.  To figure out why a particular barrel diameter is used is usually a combination of factors.  I would guess that the ones that are a nice round number, like 75mm or 8 inch, were chosen because they were in the right size range for what the designer was trying to accomplish and he picked an even number for the sake of convenience.  I would think that once a gun diameter size comes into service, there is a tendency to stick to that size for other gun designs for the sake of not having to purchase different size bore drilling equipment.  The weirdness comes in when countries switch from one measurement system to another, or buy a gun from a foreign manufacturer that uses different measurements.  So for example, the British used the completely archaic "Pounder" system in WW2.  Those that understand shotgun gauge will understand the pounder system, it's based on the weight of a lead ball that will fit inside a particular diameter.  When you convert it into someone more modern like metric, you end up with an odd number like 76.2mm.  Why did the US have both 75 and 76mm guns in tanks in WW2?  The 75mm gun on the Sherman was based on the old friench 75mm field gun.  The US had adopted the French gun back in WW1, which introduced the oddball 75mm barrel diameter into a military that still used inches.  The French probably picked 75mm because it's a nice round number in metric.  The US on the other hand traditionally used a lot of 3 inch guns.  Again, 3 inches is a nice round number.  Converting it to metric gives you 76.2mm.  So when they started designing tank destroyers, they stuck to their more traditional 3inch/76.2mm barrel diameter (although they would round the metric name down to just 76mm).  You will notice that the British 17pounder was also three inches/76.2mm.  When the British came out with the Comet Cruiser, it had a 76.2mm gun but it did not fire the same round as the 17 pounder.  To avoid confusion, they named the 76.2mm gun on the Comet the 77mm gun.  

 

Sometimes a gun diameter becomes popular due to people copying each other.  The 81mm french Brandt Me 27/31 mortar from the 1920s was such a good design that almost everyone started to copy it, making their own similar 81mm mortar.  Why did the French pick the rather odd number 81 for the barrel diameter?  Because they were copying the British Stokes mortar which was 3.2 inches (81mm).  Why did the British choose 3.2 inches?  No idea.  The Soviets, being the clever lot that they are, decided that when they would design their mortar, they would make it 82mm.  Why the extra 1mm?  So that they could fire captured 81mm ammunition but if their own 82mm ammo was captured, it could not be fired back at them from a 81mm mortar.  At least, that's the story I remember hearing somewhere.  

 


Edited by Walter_Sobchak, Apr 23 2016 - 21:25.


Walter_Sobchak #31 Posted Apr 23 2016 - 21:25

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View Poststalkervision, on Apr 23 2016 - 14:14, said:

 

Didn't Jimmy Carter propose a switch to the metric system in the USA?

 

Actually, Thomas Jefferson was the first president to recommend switching to a decimal based measurement system (at least according to wikipedia)

stalkervision #32 Posted Apr 23 2016 - 21:43

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View PostWalter_Sobchak, on Apr 23 2016 - 15:25, said:

 

Actually, Thomas Jefferson was the first president to recommend switching to a decimal based measurement system (at least according to wikipedia)

 

I didn't even know the metric system existed at the time !  I thought it was all the classic English system !  :amazed:

 

I am pretty sure that it wouldn't have gone over any better then then when Jimmy Carter proposed it along with girls being conscripted into the armed forces :)



Tjtod #33 Posted Apr 23 2016 - 21:46

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View Poststalkervision, on Apr 23 2016 - 16:43, said:

 

I didn't even know the metric system existed at the time !  I thought it was all the classic English system !  :amazed:

 

IIRC the metric system began soon after the French Revolution, when they wanted to change every form of measurement into base 10.

Edited by Tjtod, Apr 23 2016 - 21:47.


stalkervision #34 Posted Apr 23 2016 - 21:52

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Pretty interesting. If France won the French and Indian war we would all be using the metric system I bet.

 

Quarter pounder with cheese in Europe..

 

 https://www.youtube....h?v=uYSt8K8VP6k

 



Walter_Sobchak #35 Posted Apr 23 2016 - 22:05

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The one forgotten part of the French metric conversion was their failed attempt to switch over to a decimal based system of tracking time.  Anyone that has ever had to calculate payrolls based on time clocks will understand the desirability of a decimal based hour instead of the standard 60 minute hour.

Tjtod #36 Posted Apr 23 2016 - 22:09

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View PostWalter_Sobchak, on Apr 23 2016 - 17:05, said:

The one forgotten part of the French metric conversion was their failed attempt to switch over to a decimal based system of tracking time.  Anyone that has ever had to calculate payrolls based on time clocks will understand the desirability of a decimal based hour instead of the standard 60 minute hour.

 

Also a metric/base 10 calendar, is forgotten.

Crucis #37 Posted Apr 25 2016 - 01:42

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View PostWailwulf, on Apr 23 2016 - 12:26, said:

View PostCrucis, on Apr 23 2016 - 08:01, said:

 

 

It's not "illogical".  It's just a different logic.  As for being stubborn, too bad.   I'm not going to cave in to a bunch of people whose only argument is that "the rest of the world does it".  That's nothing but a lemmings argument.  You can jump off a cliff like the rest of the proverbial lemmings.  I choose not to do so.

 

 

 

Metric is in base 10, meaning the differences of measurement units is either a division or multiplyer of 10. 1,000 => 100 => 10 => 0.1 => 0.01 => 0.001

 

Standard is more of a random  number 1 Mile = 1760 yards = 5280 Feet = 63360 inches

 

Schools in the USA royally screwed up when trying to teach Metric in the Seventies, as all instruction was based on converting Metric to Imperial and back again.  What the program should have focused on was just Metric, measuring things in metric only, dont care about the Standard equivalent, just move the decimal point when changing units.

 

 

Like I said, pedantic.

 

I know full well that the metric system is based on multiples of 10.



Blackhorse_Six_ #38 Posted Apr 25 2016 - 02:07

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View PostWalter_Sobchak, on Apr 23 2016 - 16:05, said:

The one forgotten part of the French metric conversion was their failed attempt to switch over to a decimal based system of tracking time.  Anyone that has ever had to calculate payrolls based on time clocks will understand the desirability of a decimal based hour instead of the standard 60 minute hour.

 

Yep - I'm familiar with that ... :sceptic:

 

(+1) each this page ...



Tjtod #39 Posted Apr 25 2016 - 02:17

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In sciences in the US, we do use metric because they are SI units. That being said in physics the units being used have fairly simple conversion. Maybe because I'm a runner and physics students I find some of the conversions to be easy.

Edited by Tjtod, Apr 25 2016 - 02:18.


Doomslinger #40 Posted Apr 25 2016 - 03:03

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Well, the German 88 mm and American 90 mm are close in performance but the caliber is 2 mm different.  The English call the 57 mm guns, 6lber guns.  They use lbs for various calibers such as the 17 lber, 20 lber (close to 90 mm guns) etc...Caliber is not the only factor in a guns performance.  The shell length can determine shell velocity and penetration. The German short 88 mm gun uses the same caliber shell as the long 88 mm gun but the penetration is more on the long 88 because the shell casing is longer and contains more propellant.  The diameter or thickness of the actual shell is the same.

 

The Sherman tanks of ww2 had a 75 mm gun that was better at killing infantry in comparison to the higher velocity 76 mm guns that were better at penetrating enemy tank's armor.  The lower velocity 75 mm shell had more explosive impact than the 76 mm.  Some m4 tank crews that were fighting mostly against enemy infantry preferred the 75 mm gun over the newer 76 mm.

Wikipedia:

While the 76 mm had less High Explosive (HE) and smoke performance than the 75 mm, the higher-velocity 76 mm gave better anti-tank performance, with firepower similar to many of the armored fighting vehicles it encountered, particularly the Panzer IV and StuG vehicles. Using the M62 APC round, the 76mm gun penetrated 109 mm (4.3 in) of armor at 0° obliquity and 1,000 m (3,300 ft), with a muzzle velocity of 792 m/s (2,600 ft/s). The HVAP round was able to penetrate 178 mm (7.0 in) at 1,000 m (3,300 ft), with a muzzle velocity of 1,036 m/s (3,400 ft/s).[2]

 






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