05-09-2017, 02:43 PM | #41 | |
Join Date: Jun 2013
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
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Sw/cut weapons are a lot easier to leverage out, so they'd be roughly as likely to get stuck as thr/imp. My experience with axes getting stuck in logs has it being problematic simply because the logs are so light you can pick them up with the axe - once they're stabilized in some way (putting a foot on it works well) they're typically perfectly easy to remove. This is getting quite a good distance afield from the topic of this thread - blunt trauma from firearms - so if you wish to continue this part of the discussion you'll probably want to start a new thread.
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05-10-2017, 03:24 AM | #42 | ||
Join Date: Jan 2010
Location: Brighton
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
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I think my point is I'm not sure such a bullet can by itself push a target back a yard (so don't need to worry about pushing it's firer back a yard and so doesn't need to be tied to MinST) A 7.62nato is going to have about 8.3 kg m/s momentum? That will push a 100kg target (say are reasonable sized man wearing enough torso DR to stop the bullet penetrating and other kit) back at 0.083 m/s. And that's an inelastic collision no friction etc. However as said knock back is likely other things as well than just physics, but bullets don't have that much momentum There was a thread that touched on this just recently (and my later rules suggestions were wrong because of this!) Cool Quote:
Last edited by Tomsdad; 05-10-2017 at 10:25 AM. |
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05-10-2017, 10:45 AM | #43 | ||
Join Date: Jun 2013
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
You can find them on Tbone's Diner, or linked in my previously-linked thread, but they're a bit annoying to work out. I basically assumed the bullet was completely stopped by the collision (otherwise not all of the damage would have applied), and ignored the speed change suffered by the target (damage is actually based on the change in speed resulting from the collision), assuming the target was sufficiently large that this would be functionally 0. The end result is that the crushing component of a bullet is, in dice, W*V/1500, where W is weight in lb and V is velocity in mph. The annoying part, and why I didn't do it for more than three bullets, is that you need to use a weapon that's already statted in GURPS, look up muzzle velocity and weight, convert from ft/s (or m/s) and grains (or g) to mph and lb, and then run it through the calculation (and IIRC I didn't actually condense the equation as above, which made things even worse).
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Having the damage roll (not counting adds from the weapon) be at or near maximum for thrust result in an impaling weapon getting stuck is something I've considered. Thrust attacks only get stuck on particularly strong attacks, while swing attacks won't get stuck on weaker attacks. I opted against it, due to the fact that I interpret damage rolls as often being more about attack placement than the actual force behind the attack (which I think will typically be much less variable than the dice indicate).
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05-11-2017, 12:14 AM | #44 | ||
Join Date: Jan 2010
Location: Brighton
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
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What doesn't help is that it's likely different placement factors will effect damage to the overall target (itself a pretty abstract thing) and the chances of getting stuck! However if you wanted to remove placement as a variable, and worked on the assumption that placement is the overriding variable what gives the variation on damage rolls. Maybe instead of taking the damage actually rolled, take the average damage of the attack. That would be maybe a more consistent measure of how initially powerful the attack is abstract. But I can see problem where glancing blows that barely connect would be boosted by this. Last edited by Tomsdad; 05-11-2017 at 01:09 PM. |
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05-11-2017, 10:00 AM | #45 | ||
Join Date: Jun 2013
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
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*Characters with low skill still have a damage roll, but with normal damage as the best result - they are basically rolling to not screw up. I assume, absent attack options dictating otherwise (Defensive Attack, Committed Attack, or the range allowed by my Combat Posture Overhaul - which can be found on the blog in my signature), skilled combatants strike with consistent force. This isn't strictly realistic, but is close enough to justify not adding in another roll.
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05-11-2017, 10:20 AM | #46 |
Join Date: Aug 2007
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
You should be ignoring kinetic energy or force or KJ or anything besides momentum.
The Mythbusters tried this. They hung a pig in a tactical vest on a hook so it could be knocked off by a very small transfer of momentum. Tori did it with a thrown baseball. No gun they tried could duplicate that feat until maybe the shotgun slug and more clearly the .50 BMG. They had to replace the standard trauma plate with 3/4 of an inch of mild steel which the .50 BMG penetrated anyway. Note that the .50 BMG did not cause the vested pig to fly backwards energetically. It probably only went back a quarter of an inch. Of course the thrown baseball didn't cause anything but the barest amount of backward movement either. You sometimes see what is clearly Gurps Knockback on the football field but no reasonable bullet meets armor scenario will create any. 100 kg men at over 6 or 7 meters per second sometimes but no bullets. So I wouldn't introduce massive house rules to "fix" this "problem". I certainly wouldn't think I could ever make it square with raw damage.
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05-11-2017, 10:33 AM | #47 |
Join Date: Jun 2013
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
Apologies if I was unclear - my post was meant to defend the amount of crushing damage I suggested for bullets, and simply note that the high amount of knockback this results in is an oddity of the GURPS Knockback rules, which are already at least mildly cinematic. I was further indicating that the Knockback, while unrealistic, is probably within the realm of standard GURPS cinematics. Essentially, strong characters using weapons at or near the maximum of what they can carry around and fire will cause a yard or two of Knockback on a weaker character, provided the bullet is stopped by the target's armor. It's unrealistic, but not something that would seem out of place or comical in even a low-cinematic action movie, for example (it would be unrealistic in a movie that tries to be realistic, but the bulk of the audience probably wouldn't even notice).
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05-12-2017, 12:18 AM | #48 | ||
Join Date: Jan 2010
Location: Brighton
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
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Against a limb a rifle bullet won't do full HP in injury (it's capped at half HP*). When it comes to rifle bullets even if they don't hit bone they can take a reasonably large chunk of flesh out (thanks in part to key holing**). However I do agree the practically automatic nature of them doing so is a problem. And shorter and less powerful pistol rounds are on average too capable of doing so as well. One tweak here might be to apply doubling the threshold for dismembering / severing rule from HT "limb hits" (HT pg162) to the crippling threshold as well. That will not really effect a lot of rifle wounds, but will limit pistol rounds ability to do so a bit *well OK half rounded up or half +1 **TBF This gets complicated as not all rifle rounds in all limbs will have the space/time to turn 90 degrees to get the largest wound track, lots of variables here! But equally crippling at it's most basic just means you disrupted the limb's ability to function enough for it not to be used. There are several ways you can do this in a limb without breaking a bone or ripping out entire muscles. But then that said limb's can keep working through a lot of damage as well (including broken bones)! Basically as ever with the effect of damage on people, lots of variables! Either way If we're really looking at this I'd would adjust the crippling threshold for legs vs. arms, (legs and arms are rarely the same size/mass) Last edited by Tomsdad; 05-12-2017 at 12:31 AM. |
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05-12-2017, 11:19 AM | #49 | |
Join Date: Jun 2013
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Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers
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I was originally going to respond point by point with how I intend my system to handle this, but I think I'm starting to derail the thread a bit with discussion of a bare-bones system that still needs a lot of work, so I think I'll stop where I am on that, and only really discuss the blunt trauma bullet issue.
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armor, ballistic, non-penetrating, punched by a baby, trauma |
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