Nitpicking: The .600 Nitro versus the .700

[Tallor]

In GURPS: High Tech, page 120, the H&H Royal Double in .600 Nitro Express does 5dx2 pi++ damage... but on page 112, the book mentions that the .700 Nitro Express also does 5dx2 pi++. I was sorely disappointed!

Now technically you could use the extra bulk of the .700 for more powerful HE rounds and other diabolical bullets, but the question remains--should the .700 really be more powerful, or is it even more of a showboat gun than the regular .600?

[AlexanderHowl]

Well, the damage of a bullet is proportional to the velocity of the bullet and the cube root of the mass of the bullet. The .700 is only modestly heavier, but it possesses slightly less velocity than the .600, so the damage is not really that much of a concern. The lower range, however, is probably an error, since a heavier bullet would retain momentum longer than a lighter bullet, but I am not a ballistics expert.

[Tomsdad]

If you want to see a difference that's supported by the game system you can go with extending the "bigger is better" rules from Monster Hunters: Load outs.
This rule is designed to spilt the Injury mod for Pi+ rounds i.e 10-14.99mm calibre, into further sub bands of 1mm, rather than just all calibres 10-14.99mm = Pi+ (x1.5). The net result is it basically gives a boost to gun calibres 11mm - 14.99mm, and if you extend the progression a boost to calibres in the 16mm+ ranges


With this

the .600 (15.24mm) stays at 5dx2 with a multiplier of x2.0

the .700 (17.78mm) increases to 5dx2 with a multiplier of x2.2

This rule was brought in to monster hunters in order to encourage the large hand cannon troupe though so bear that in mind. (it also doesn't work if you extend the progression* in the other direction to sub 10mm, as the current sub 10mm bands, Pi & Pi- are not 4.99mm wide)



*it does however stop the .40 S&W being a goldilocks round, (but by boosting most smaller rounds though so be warned)!

[Tallor]

Originally Posted by Tomsdad

If you want to see a difference that's supported by the game system you can go with extending the "bigger is better" rules from Monster Hunters: Load outs.
This rule is designed to spilt the Injury mod for rounds 10-14.99mm into further sub bands of 1mm diameter, rather than just all calibres 10-14.99mm = Pi+ (x1.5) The net result is it basically gives a boost to gun calibres 11mm - 14.99mm, and if you extend the progression a boost to calibres in the 15mm+ ranges


With this

the .600 (15.24mm) stays at 5dx2 with a multiplier of x2.0

the .700 (17.78mm) increases to 5dx2 with a multiplier of x2.2

This rule was brought in to monster hunters in order to encourage the large hand cannon troupe though so bare that in mind. (it also doesn't work if you extend the progression* in the other direction to sub 10mm, as the current sub 10mm bands are not 4.99mm wide)



*it does however stop the .40 S&W being a goldilocks round, (but by boosting most smaller rounds though so be warned)!

Believe it or not I did the math on that a while ago, though I was a bit more reluctant to invent a new piercing modifier to accompany it. I'll call it Pi+++, or Wumbo Piercing.

More to the point though, all I wanted was to know if the .700's damage checked out with fellow gamers, since I'm not great with joules and inertia...

[Tomsdad]

Originally Posted by Tallor

...
More to the point though, all I wanted was to know if the .700's damage checked out with fellow gamers, since I'm not great with joules and inertia...

I think the usual answer to this one (it has come up before) is that while obviously both rounds don't have identical KE,


.600 Nitro express 900gr 11,146J

.700 Nitro express 1,000gr 12,100J

(and I'm sure there's variation in rounds as well of course)

they end up the same(ish) rating on various terminal ballistics calculations used for GURPS. Not sure if they have been put through all of the commonly used ones out there though. (someone might want to run the numbers again*)

But yes when it comes to as broad a question as "how much damage does this do to a thing" it's going to depend on how you calculate it and more importantly transfer it into GURPS terms.




*I'd not be surprised to see the that extra 1,000J and size means a few extra points on average against flesh, but I think the reality is for effect on human scale target's its really just going to be bleeding to death a bit more quickly out of a larger hole (which is what upping the injury mod does) or being even more dead on a vitals/skull hit.

A factor here is I think that damage is based on the ability to penetrate RHA which is in turn based on a energy/cross-section relationship. So the slightly slower, more massive and energetic .700 might not see an advantage in this over the slightly faster but smaller and less energetic .600 Because the decrease in penetrative ability due to increased cross-section compensates for the in creases in penetrative ability due to increased energy.

The link to the earlier thread goes into more detail on all this


EDIT and yep I just ran both through one of the calculators and got the .600 as 11.81 dice of damage and the .700 as 11.55 dice of damage, so yeah not a lot of difference (0.26 of dice is what less than 1pt) and within a rounding of each other (In HT terms that's 12d-1 and 11d+2)

[Purple Haze]

Real world killing power is ~ k * mv * mv^2

So if both bullets are of the same shape and construction, the .700 should be 1.19 times the .600.