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Old 02-06-2020, 06:23 PM   #11
Sam Cade
 
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Agemegos View Post
Why .357 magnum?
It has to do with legacy technology nomenclature.

https://en.wikipedia.org/wiki/Heeled_bullet
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Old 02-06-2020, 06:27 PM   #12
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

Well, in the case of .308 Winchester and all those other ".308" rounds, they had a barrel with a bore of .30", which happens to require a bullet diameter of .308" to seal it properly.

I'm not sure why .303 is that calibre, but the bullets are actually 0.311" for a 0.303" bore. Nor do I know why 5.56mm rounds are 5.56mm/0.218" or 0.219", with bullets of either 0.223" or 0.224", except that .22 Long Rifle and other rounds of similar vintage were in that calibre.

.270 Winchester (and other .270 rounds) use bullets of 0.277" (exactly 7mm) in a 0.270" bore. "7mm" rifles use 0.284" bullets in a 7mm/0.277" bore.

Oh, and to make matters even nuttier, the US tends to measure barrel diameter groove-to-groove, and Europe tends to use land-to-land.

Then there's rounding, and 'cool name' effects - .38 rounds have actual bullet diameters of 0.357"/9.07mm for a 9mm bore, and the name comes from the cartridge neck's external diameter.

Basically, there's no rhyme nor reason to cartridge names or dimensions, though there might be for a given individual round.
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Old 02-06-2020, 06:56 PM   #13
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Agemegos View Post
Ooh! I know that one! 7.92 mm is 0.3 Zolle, where one Zoll is a twelfth of a Fuß. The English weren't the only people to have a bewildering mess of customary units before adopting metric!
0.3 Zolle? Why didn't they use 1/3 of a Zolle? What's with all this mixing of fractional and decimal standards!? :) (Aside: I love base 60 and base 12 systems because they divide by whole numbers so easily)

Quote:
The same question has often puzzled me with respect to Imperial and US units. Why .357 magnum? Why .303 British? Why .276 Enfield? Why .455 Webley? Why .338 Lapua magnum? Why .351 Winchester? Why .454 Casuli?
Some of the 'three digit' caliber labeling is because it sounds cool. Examples: .454 sounds like a car engine. .444 Marlin is a bigger .44 Magnum. .357 sounds better than .38++ or .36 Long etc. although I think Sam's note that it has to do with groove vs. lands measurements apply in most of the cases.
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Old 02-06-2020, 08:10 PM   #14
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Kale View Post
0.3 Zolle? Why didn't they use 1/3 of a Zolle?
Well, possibly 8.8mm would have been Too Much Bullet.

Alternatively they were trying to copy the mighty .30-40 Krag and mis-translated "inches" as Zolle.
"A Fuß is a foot, right? And an inch is a twelfth of a foot, so an inch is a Zoll. 0.30 Zolle".

"And what is a 'grain', then?"

"Umm. 65 milligrams."

"I hate you."
They ended up firing their "7.92mm" cartridges through barrels that were 7.9mm between the lands and 8.2mm between the grooves, so the designation really was an overly precise metric conversion of an approximate calibre in obsolete units, while the thing was actually specced in tenths of a millimetre.
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Old 02-06-2020, 08:10 PM   #15
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

Quote:
Originally Posted by Kale;
think Sam's note that it has to do with groove vs. lands measurements apply in most of the cases.
Sometimes.

Nomenclature is mostly just whim and advertising.


In the US we actually have an organized body to try and get some standards in play and keep folks from blowing themselves up but realistically I suppose they have spent the last century mostly herding cats, gun-people being the way we are.

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Moar Powah. I'm going to make major changes to this cartridge case jeeeeest because I can. I shall name it .47 Thunderfist.
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Old 02-06-2020, 10:33 PM   #16
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

Also note that both the SAAMI and C.I.P call the 7.92x57mm Mauser "8x57". The original version was called the Patrone 88 by the German military, and the next version (with the modern dimensions) the S Patrone. The British called it "7.92mm" when issued to their tank units for the Besa machinegun, which may be where it became commonly known as 7.92mm.
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Old 02-07-2020, 12:56 PM   #17
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Ulzgoroth View Post
If you look at the numbers, they aren't actually that weird.

5mm and 7mm are obviously truncations of the most common modern rifle calibers. The reduction isn't negligible, but it's only around 10%. <snip>
I don't know what counts as a "weird" caliber, but I don't think these calibers are mere stand-ins for their slightly larger real-world cousins. They seem to do about 10% less damage rather than just using stats for those common modern rifles. I'd be interested to see canonical stats for those 6.8mm or 0.27 in or whatever modern rifles.

For black powder weapons I wasn't suggesting having 5mm or 10mm examples, more like 10mm and 15mm versions of say the Kentucky rifle whose official stats in HT are for 0.45 in. I think higher calibers for spherical bullets should have longer range holding muzzle velocity constant due to a higher ratio of mass to cross-sectional area but I'm not certain.
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Old 02-07-2020, 04:58 PM   #18
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Michael Thayne View Post
I don't know what counts as a "weird" caliber, but I don't think these calibers are mere stand-ins for their slightly larger real-world cousins. They seem to do about 10% less damage rather than just using stats for those common modern rifles. I'd be interested to see canonical stats for those 6.8mm or 0.27 in or whatever modern rifles.
From HT:

7x57mm Mauser: 6d+2 pi
6.5x50mmSR Arisaka: 6d pi

About what you'd expect from a full-power military cartridge of the late 19th/early 20th century.
Quote:
For black powder weapons I wasn't suggesting having 5mm or 10mm examples, more like 10mm and 15mm versions of say the Kentucky rifle whose official stats in HT are for 0.45 in. I think higher calibers for spherical bullets should have longer range holding muzzle velocity constant due to a higher ratio of mass to cross-sectional area but I'm not certain.
They do. Also, the bigger the bore the less fouling affects the ability to load the weapon without cleaning it constantly.
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Old 02-07-2020, 05:16 PM   #19
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Rupert View Post
From HT:

7x57mm Mauser: 6d+2 pi
6.5x50mmSR Arisaka: 6d pi

About what you'd expect from a full-power military cartridge of the late 19th/early 20th century.
Good catches. I also found a 6.8mm weapon in Tactical Shooting. The 6.8mm weapon is TL8 and its stats are pretty darn close to the TL9 7mm weapon. Also, after more research it seems like the weight of a modern cartridge is generally around 50% brass, at most? Given that I might go with cased versions of TL9 caseless weapons halving half as many shots and otherwise being identical.
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Old 02-07-2020, 05:26 PM   #20
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Default Re: TL 5-8 firearms in Ultra-Tech calibers

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Originally Posted by Michael Thayne View Post
Good catches. I also found a 6.8mm weapon in Tactical Shooting. The 6.8mm weapon is TL8 and its stats are pretty darn close to the TL9 7mm weapon. Also, after more research it seems like the weight of a modern cartridge is generally around 50% brass, at most? Given that I might go with cased versions of TL9 caseless weapons halving half as many shots and otherwise being identical.
Why half as many shots? A cased round will be heavier and might be longer, but it doesn't need to be much wider. Which is usually the limiting dimension for magazine capacity.
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