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Old 11-21-2016, 07:39 AM   #1
Donny Brook
 
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Default Large Caliber Auto Rifles?

Has anyone statted any of this ammo into automatic rifles for GURPS?

https://en.wikipedia.org/wiki/.458_Winchester_Magnum

https://en.wikipedia.org/wiki/.416_Rigby

https://en.wikipedia.org/wiki/45_Raptor

https://en.wikipedia.org/wiki/.450_Bushmaster

If so, I'd love to see what you've come up with. As a second choice, I'd take a tutorial on Mr. Cole's spreadsheet. I've not been able to make it go.
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Old 11-21-2016, 08:12 AM   #2
Fred Brackin
 
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Default Re: Large Caliber Auto Rifles?

Quote:
Originally Posted by Donny Brook View Post
Has anyone statted any of this ammo into automatic rifles for GURPS?

https://en.wikipedia.org/wiki/.458_Winchester_Magnum

https://en.wikipedia.org/wiki/.416_Rigby

https://en.wikipedia.org/wiki/45_Raptor

https://en.wikipedia.org/wiki/.450_Bushmaster

If so, I'd love to see what you've come up with. As a second choice, I'd take a tutorial on Mr. Cole's spreadsheet. I've not been able to make it go.
<shrug> Take a .50 BMG and add a stock and some hand-grips. None of those rounds are all that much less powerful than the .50. You're going to end up with weights over 30 or 40 lbs and Min ST of at least 20. Not really a "rifle" for humans.

If you enant "self-loading" or "semi-automatic" rather than _full_ automatic you've just got an adaptation of the .50 Barrett which already is semi-automatic.
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Old 11-21-2016, 08:41 AM   #3
Anaraxes
 
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Default Re: Large Caliber Auto Rifles?

As for the Cole spreadsheet, you fill out all of the numbers in the "INPUT" section (column D, rows 13:22 in the version I have) and it gives you results in the "OUTPUT" section below that. Coming up with all the numbers the input section wants might take some research, though. Some of them are more obscure than others.

(Sometimes when I fool around, I just change numbers like burn length or chamber pressure to get the right output velocity, rather than hunting them down. That might break something somewhere else, of course.)
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Old 11-21-2016, 09:57 AM   #4
RyanW
 
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Default Re: Large Caliber Auto Rifles?

Quote:
Originally Posted by Fred Brackin View Post
<shrug> Take a .50 BMG and add a stock and some hand-grips. None of those rounds are all that much less powerful than the .50. You're going to end up with weights over 30 or 40 lbs and Min ST of at least 20. Not really a "rifle" for humans.
All of them have substantially less than half the energy of a .50 BMG, and the Bushmaster is less than a quarter. The Raptor and Bushmaster are both specifically designed to be fired from modified autoloading rifles (the AR-10 and AR-15/M-16, respectively).

For damage, you could get in the right range for a round close to .45 caliber by giving it 2d*sqrt(energy in ft-lbs/352).
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Old 11-21-2016, 10:11 AM   #5
Donny Brook
 
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Default Re: Large Caliber Auto Rifles?

Quote:
Originally Posted by Anaraxes View Post
As for the Cole spreadsheet, you fill out all of the numbers in the "INPUT" section (column D, rows 13:22 in the version I have) and it gives you results in the "OUTPUT" section below that. Coming up with all the numbers the input section wants might take some research, though. Some of them are more obscure than others.

(Sometimes when I fool around, I just change numbers like burn length or chamber pressure to get the right output velocity, rather than hunting them down. That might break something somewhere else, of course.)
Thank you, I'll take a look again and see if I can decipher it now.


Regarding the ammo's comparative power, I chose types that had no more than +50% of the energy of a .30-06 (the WinMag). The Bushmaster is comparable to the .30-06 and the Raptor is about +20%.
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Old 11-21-2016, 11:35 AM   #6
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Default Re: Large Caliber Auto Rifles?

All of these rounds fire fairly heavy bullets with low muzzle velocity. This is not a generally desirable property for an automatic rifle, as it means recoil is high unless the gun is extremely heavy.
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