Modern and old west firearms in GURPS.

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Has anyone ever looked at ballistics information for modern firearms and old
west firearms? The .45 acp fires approximately the same size slug as the
..45 long colt. It also delivers more energy, but it is listed as 2d damage,
while the long colt is 2d+1.

Has anyone come up with any formulas for determining damage based on
ballistics?

 

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On Fri, 2 Sep 2005 21:09:31 -0500, "B.J. McNail"
<bjmcnail@centurytel.net> carved upon a tablet of ether:

> Has anyone ever looked at ballistics information for modern firearms and old
> west firearms? The .45 acp fires approximately the same size slug as the
> .45 long colt. It also delivers more energy, but it is listed as 2d damage,
> while the long colt is 2d+1.

What are your sources? Some fo the older books had "it looks about
right" damage ratings (some of which made it all the way through to
the end of 3e's life, unfortunately). Also, some modern loads for .45
Colt take advantage of its larger case to get more energy than the .45
ACP can manage. Mostly it's likely to have been somebody deciding
"Peacemakers are cool" - compare the M1 Garand's damage to that of the
Mosin-Nagant or any 7.92mm Mauser for another example (fixed in 4e).

> Has anyone come up with any formulas for determining damage based on
> ballistics?

Damage is fairly close to being proportional to the square root of
muzzle energy, though many .45 calibre pistol rounds have their damage
reduced because otherwise the x1.5 multiplier for bore size would be
unreasonable (and because they penetrate poorly compared to their
wounding potential).

A reasonable approximation is:

[muzzle energy 9ft=lbs)]^0.5 / 7 = No. Dice

--
Rupert Boleyn <rboleyn@paradise.net.nz>
"Just because the truth will set you free doesn't mean the truth itself
should be free."

 

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Rupert Boleyn wrote:
> On Fri, 2 Sep 2005 21:09:31 -0500, "B.J. McNail"
> <bjmcnail@centurytel.net> carved upon a tablet of ether:
>
> ACP can manage. Mostly it's likely to have been somebody deciding
> "Peacemakers are cool" - compare the M1 Garand's damage to that of the
> Mosin-Nagant or any 7.92mm Mauser for another example (fixed in 4e).

M-1 Garand: 150 grain bullet, 2805 fps, energy 2344 ft/lbs
M1891/30 Mosin-Nagant: 148 grain bullet, 2660 fps, energy 2326 ft/lbs
Carbine 98k: 198 grain bullet, 2476 fps, energy 2696 ft/lbs

(bullet weight and muzzle velocityfrom _Small Arms of the World_, Smith
& Smith, 1973; energy calculated with formula from _The Firearms
Dictionary, Steindler, 1970)

Brandon

 

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Rupert Boleyn wrote:
> On 3 Sep 2005 19:43:37 -0700, "copeab@yahoo.com" <copeab@yahoo.com>
> carved upon a tablet of ether:
>
> > Rupert Boleyn wrote:
> > > On Fri, 2 Sep 2005 21:09:31 -0500, "B.J. McNail"
> > > <bjmcnail@centurytel.net> carved upon a tablet of ether:
> > >
> > > ACP can manage. Mostly it's likely to have been somebody deciding
> > > "Peacemakers are cool" - compare the M1 Garand's damage to that of the
> > > Mosin-Nagant or any 7.92mm Mauser for another example (fixed in 4e).
> >
> > M-1 Garand: 150 grain bullet, 2805 fps, energy 2344 ft/lbs
> > M1891/30 Mosin-Nagant: 148 grain bullet, 2660 fps, energy 2326 ft/lbs
> > Carbine 98k: 198 grain bullet, 2476 fps, energy 2696 ft/lbs
> >
> > (bullet weight and muzzle velocityfrom _Small Arms of the World_, Smith
> > & Smith, 1973; energy calculated with formula from _The Firearms
> > Dictionary, Steindler, 1970)
>
> What's the formula you used? The standard one is [bullet weight in
> grains]/7000 x 0.5 / 32.2 x [muzzle velocity]^2. This gives you stats:

E = (W * V^2)/450,240

This is mathematically the same as the formula you list.

> .30-06: 2618 ft-lb

I did some dyslexic typing when I was figuring the square of velocity
-- 2805 x 2508

> 7.62x54mmR: 2323 ft-lb

Rounding.

> 7.9x57mm: 2693 ft-lb

Rounding.

<snip>

My only other source (The Encyclopedia of Weapons of WWII, Bishop,
Barnes & Noble, 1998) lists the same muzzle velocities as my other
source (with the 98K being 1 fps higher).

> Either way, the M1 does not rate 7d+1 when the other rounds are only
> granted 7d.

My numbers indicate a 6d+2 or 7d-1 for the M-1 and M1891/30 and 7d+1
for the 98K.

(Avg Dam = Sqrt(Energy)/2)

Brandon

 

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Rupert Boleyn wrote:
> On 3 Sep 2005 23:02:06 -0700, "copeab@yahoo.com" <copeab@yahoo.com>
> carved upon a tablet of ether:
>
> > My numbers indicate a 6d+2 or 7d-1 for the M-1 and M1891/30 and 7d+1
> > for the 98K.
> >
> > (Avg Dam = Sqrt(Energy)/2)
>
> I use Dice = (energy^0.5)/7, which happens to be effectively the same.

I like your formula better since you don't have the extra step of
dividing average damage by 3.5

Brandon

 

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On 3 Sep 2005 19:43:37 -0700, "copeab@yahoo.com" <copeab@yahoo.com>
carved upon a tablet of ether:

> Rupert Boleyn wrote:
> > On Fri, 2 Sep 2005 21:09:31 -0500, "B.J. McNail"
> > <bjmcnail@centurytel.net> carved upon a tablet of ether:
> >
> > ACP can manage. Mostly it's likely to have been somebody deciding
> > "Peacemakers are cool" - compare the M1 Garand's damage to that of the
> > Mosin-Nagant or any 7.92mm Mauser for another example (fixed in 4e).
>
> M-1 Garand: 150 grain bullet, 2805 fps, energy 2344 ft/lbs
> M1891/30 Mosin-Nagant: 148 grain bullet, 2660 fps, energy 2326 ft/lbs
> Carbine 98k: 198 grain bullet, 2476 fps, energy 2696 ft/lbs
>
> (bullet weight and muzzle velocityfrom _Small Arms of the World_, Smith
> & Smith, 1973; energy calculated with formula from _The Firearms
> Dictionary, Steindler, 1970)

What's the formula you used? The standard one is [bullet weight in
grains]/7000 x 0.5 / 32.2 x [muzzle velocity]^2. This gives you stats:

..30-06: 2618 ft-lb
7.62x54mmR: 2323 ft-lb
7.9x57mm: 2693 ft-lb

The M1 Garand actually used M2 Ball, which was loaded to 2700 ft/s
with a 150 grain projectile (the same stats the 7.62x51mm NATO ball
round has).

Barnes gives the 7.62x54mmR a 147 grain bullet at 2886 ft-s, and I've
never seen anyone list it as less powerful than the .30-06 (in the
standard ball loadings).

Barnes also gives the 7.9x57mm as having a 154 gain bullet at 2880
ft/s.

These give:
..30-06: 2426 ft-lb
7.62x54mmR: 2716 ft-lb
7.9x57mm: 2833 ft-lb

Either way, the M1 does not rate 7d+1 when the other rounds are only
granted 7d.

--
Rupert Boleyn <rboleyn@paradise.net.nz>
"Just because the truth will set you free doesn't mean the truth itself
should be free."

 

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On 3 Sep 2005 23:02:06 -0700, "copeab@yahoo.com" <copeab@yahoo.com>
carved upon a tablet of ether:

> My numbers indicate a 6d+2 or 7d-1 for the M-1 and M1891/30 and 7d+1
> for the 98K.
>
> (Avg Dam = Sqrt(Energy)/2)

I use Dice = (energy^0.5)/7, which happens to be effectively the same.

--
Rupert Boleyn <rboleyn@paradise.net.nz>
"Just because the truth will set you free doesn't mean the truth itself
should be free."