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Old 12-05-2017, 05:28 PM   #1
Shayd3000
 
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Location: Franklin County, PA
Default GUN Need to stat out a Weatherby .270 Winchester

Need to stat out a Weatherby chambered for .270 Winchester. Did not see any examples in High Tech or Tactical Shooting. Looking for some inspiration.

Plus, and I'm sure it's been asked a million times, but the search engine keeps deleting my search on "custom guns" as too short a word. Any chance that the formulas for fps to GURPS damage might ever be shared so we can do our own conversions? I got a very long guns list that I would like to tackle.

Thanks for help on the .270!

George
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Old 12-05-2017, 05:35 PM   #2
Say, it isn't that bad!
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

Quote:
Originally Posted by Shayd3000 View Post
Need to stat out a Weatherby chambered for .270 Winchester. Did not see any examples in High Tech or Tactical Shooting. Looking for some inspiration.

Plus, and I'm sure it's been asked a million times, but the search engine keeps deleting my search on "custom guns" as too short a word. Any chance that the formulas for fps to GURPS damage might ever be shared so we can do our own conversions? I got a very long guns list that I would like to tackle.

Thanks for help on the .270!

George
If you mean "Google" is deleting your search, then I'd suspect your country's filters. If you mean SJG's, you can search forums on Google like so:

Custom Guns

But, from a practical perspective, grab the closest Winchester/other rifle and fudge the stats a bit, if you just want something for a single session/encounter.

Otherwise, just wait a few minutes for someone else to reply. :)
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Old 12-05-2017, 06:38 PM   #3
johndallman
 
Join Date: Oct 2010
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

Pulp Guns 2, one of the supplements to High-Tech, has a rifle in .270 Winchester. All rifles for the same cartridge have pretty much the same damage, range and so on.

The alternative way to do it is to look in High-Tech for a rile that fires a similar cartridge, then look up the cartridge stats in Wikipedia and adjust. For this kind of non-military cartridge, the Remington 700 is a good start, and the closest calibre cartridge it has stats for is the 7mm Remington Magnum. So you look up .270 Winchester and 7mm Remington Magnum, and you'll find they have pretty similar velocities and energies, with the .270 Winchester just a little bit less powerful. Say, take a point of damage off.

These two methods give me damage figures that differ by one point, with the Wikipedia method -- based on modern cartridge loadings -- being higher. Since the Pulp Guns 2 numbers are for the 1920s loading of the cartridge, this seems entirely plausible.
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Old 12-05-2017, 08:27 PM   #4
Fred Brackin
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

Quote:
Originally Posted by Shayd3000 View Post
. Any chance that the formulas for fps to GURPS damage might ever be shared
http://www.sjgames.com/pyramid/sample.html?id=2794

You might need to contact the author for more detail but the "formula" is rather more complicated than just fps.

I've never found great need for it. Real word guns vary over only a small range of damage and distance. You're not going to find anything greatly different than what's already published.
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Old 12-05-2017, 08:38 PM   #5
hal
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

Search on Ballistics in the forums, or on Ultratech ballistics. There will be some information there on ballistics. Also, I sent you a private message. Email me and I'll send you my derived spreadsheet (based on Doug Cole's spreadsheet) that only requires Muzzle velocity (Feet per second), bullet weight (in grains), bullet diameter (in mm) and an aspect ratio if you can find it, or estimate it at around 2:1 if you can't find it. The spreadsheet will give you bullet damage and 1/2 damage (per Doug's formulas). While the damage rating will be close to published material if you compare them against published GURPS stats, the Half Damage ratings might be a touch off, but they'll be in the ball park at least. ;)
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Old 12-05-2017, 08:38 PM   #6
Colarmel
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

FPS isn't how gun damage works. It's FPS and projectile weight. FPS is only half the equation.
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Old 12-05-2017, 10:36 PM   #7
hal
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

Quote:
Originally Posted by Colarmel View Post
FPS isn't how gun damage works. It's FPS and projectile weight. FPS is only half the equation.
As pointed out in my post: muzzle velocity plus bullet diameter plus bullet weight plus aspect ratio are the required variables. The aspect ratio is used (iirc), to help determine 1/2 damage range. The other three are necessary for damage values as well as calculating 1/2 damage range.

I could have set it up for strict units such as meters per second, grans, and diameter in mm, but the reference books Iím using generally list velocity in feet per second, weight in grains, etc. It is easier to convert from caliber to mm, so I went with that.

I suppose I could add a section that lets one use any given statistics in any given measurenent system. Hmmm, food for thought.
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Old 12-06-2017, 08:55 AM   #8
hal
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

OK, after doing some digging into the issue, this is one webpage that I was able to find on ballistics for the .270 Winchester. Click on the word ballistics to go to that web page. It will give you the bullet weights in grains by manufacturer as well as muzzle energy and muzzle velocity.

If you select which round you want me to work with, let me know. In the meantime, I'll see if I can get a reasonable "accuracy" value for the weapon in question, along with rifle weight etc...
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Old 12-06-2017, 08:59 AM   #9
hal
 
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Location: Buffalo, New York
Default Re: GUN Need to stat out a Weatherby .270 Winchester

Is THIS webpage sufficiently close to what you had in mind Shayd3000?

Addenda: I found a list of some bullet lengths versus diameters along with bullet weights HERE. If anyone knows a web page that contains more rounds for various bullets than showing at this site, please feel free to list it here...

:)

Last edited by hal; 12-06-2017 at 10:30 AM. Reason: Added another link
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Old 12-06-2017, 04:32 PM   #10
Shayd3000
 
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Default Re: GUN Need to stat out a Weatherby .270 Winchester

Thanks all!

The one linked is a magnum. Not doing a magnum.

I've done all my other conversions using what's listed in the books, but since I don't have Pulp Guns, I never found an entry for the .270. Guess it'll be a good reason to get it.

I do plan to play with Hal's spreadsheet a bit, it looks promising though I have some concerns - but I need to play to see if those are born out. This is a game, so really, I just want to get close. That said, my game has gun people in it, that is folks that carry and use guns. They can sometimes be put off a bit if the game and their perceived differences in varying guns are not reflected. So far, most issues we've had we've dismissed with "granularity" or, "does it really matter"? and so far that's worked out rather well. Still for me, I want to get close.

Still would like to see the formulas - so many guns out there - and so many new guns released since High Tech came out. Would like to account for some of them.

All - thanks again! You've been very helpful.

George
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