12-07-2009, 08:47 AM | #1 |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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'Shotguns have dkb/dbt' - where did that myth (?) come from?
Greetings, all!
Several times in my life I've encountered the opinion that shotgun attacks have so much 'push' that despite not penetrating the armour (vest or whatever), the blast is enough to break ribs, cause internal bleeding etc. I've even heard of an 'advanced' bulletproof vest which was made not only hard but heavy specifically to resist this 'shock'. I think this is wrong, judging by many posts of the local guns experts, but of course I could've misinterpreted them. So it's a myth, right? Where did it come from, especially the 'shot-proof vest'? Thanks in advance! |
12-07-2009, 09:07 AM | #2 |
Join Date: Dec 2006
Location: Eindhoven, the Netherlands
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Movies.
You can really see this, for example, in Hard Boiled.
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12-07-2009, 09:51 AM | #3 |
Join Date: Mar 2009
Location: Detroit
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Any firearm has the potential for that sort of thing. Shotguns just tend to pack more energy into the whole, personally I think a lot of it is wasted with pellet dispersal, or something.
Anything that completely stops the projectile(s) will absorb that energy. Pistol rounds into a bullet proof vest will do it as well, there's just a lot less energy to start with. (All you guys with the slide rules, calm down. All I'm saying is there's a lot more propellant in a 12g shell than a 9mm cartridge.) I guess there are two factors: 1) How flexible the armor is. I've worn Vietnam-era flak jackets, and trust me, nothing that you will survive is likely to do blunt trauma through it. 2) How powerful the round is. A .50 Browning round is gonna hurt through even semi-flexible armor. In fact, that one might actually hurt through a half inch of solid steel, because if you aren't using the armor piercing (which will go through that like a hot knife through butter) it *will* bend the steel, making it semi-flexible, at least for that round. A 9mm barely hurts through clothes (my opinion- it definitely makes a hole, I'm just saying the contusions from non-penetrating wounds is way low compared to the bloody part). I've had .38's, almost the same as 9mm but a bit more powerful, actually bounce off of plywood. From the same range, a shotgun will rip a hole the size of a baseball or softball (depending on other factors). Bottom line is, with enough energy, any round will do what you're saying. Shotguns are just the most likely culprit, because handguns are wimpy compared to long guns, and people tend to use shotguns much more than high (super?) powered rifles. (Note I'm talking something above normal military calibers, perhaps sniper size for long ranges. Normal hunting rounds would likely be a little less energy than shotguns, but that energy would be delivered at about the same amount at a much greater range.) Range is also a factor, if you've ever looked at the way bullet resistant vests are rated, they mention it was tested and able to stop X caliber at Y distance. So while they say 'able to stop a shotgun', it's more a measure of overall performance, with shotgun being at the top of the list of likely threats. I have never seen one say 'able to stop high-powered rifles', because when you start getting into the high end of the performance there, you can get into some hugely powerful stuff that you can't stop without boiler plate. (Like the .50 armor piercing where even 1" of solid steel just won't work.) |
12-07-2009, 09:51 AM | #4 | |
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Quote:
The 7 kg arm of a karate master punching at 7 m/s will have 170 J of kinetic energy and 49 N-s of momentum. Top karate experts can go a bit faster, up to 10 to 15 m/s, for a maximum of perhaps 100 N-s and 700 J of kinetic energy. A boxing champion (Rocky Marciano) once has the energy of his punch measured at 1250 J using a ballistic pendulum. Very roughly, momentum is what pushes things around, and energy is what stretches, tears, and breaks things. A punch will push someone around more than a shotgun slug, but even if stopped by a ballistic vest, the energy of the impact will still be able to break things much better than a punch - by about an order of magnitude. It is estimated that a leg bone takes about 350 J to break, an arm bone about 90 J, and a rib bone perhaps 30 J. So a strike by a shotgun slug stopped by a ballistic vest can still smash plenty of ribs. That is assuming that the energy is efficiently transferred from the slug to the ribs. Trauma plates can distribute the energy over a wider area, and padding and stretchy Kevlar fibers can use up some of that energy before it gets to the torso. I suspect you are still looking at bruising and cracked ribs, though, even if your chest isn't caved in. However, the paucity of momentum compared to a punch means that a shotgun slug will not be particularly good at knocking people over. They might, however, drop to the ground from pain after getting their ribs smashed up. Luke |
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12-07-2009, 10:34 AM | #5 | |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Quote:
Of course, knocking someone back with a punch also pretty much doesn't happen, unless they fall over from the shock. About the only impacts which realistically cause any level of knockback are collisions or other similar attacks which involve the full body weight behind the blow. |
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12-07-2009, 10:37 AM | #6 | |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Quote:
I'm also surprised that a punch of a respectable combatant is less than 10m×s^-1. |
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12-07-2009, 10:40 AM | #7 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Depends on what you count as being the arms, but in any case, that would give 7 kilograms for both arms put together, and at that weight probably includes upper arms and shoulder, which aren't really part of the impact mass of a punch.
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12-07-2009, 10:46 AM | #8 |
Join Date: May 2008
Location: CA
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
A well-delivered punch shouldn't just use the mass of the arm, should it? I'd think a power punch would involve putting the torso behind the blow rather than just the arm - or at the very least, the shoulder.
Then again, I haven't practiced any martial arts in over thirteen years and the only time I punched anything since then I broke one of my fingers, so I'm not exactly an expert. |
12-07-2009, 10:50 AM | #9 |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
Yes and no. An arm by itself is (for simplicity, if not anything else) considered as the part which moves when the torso is fixed, i.e. everything from the shoulderjoint. But the thing is, a punch doesn't involve just the arm moving. It involves the torso turning, a large aid from the hips, and (assuming something like [url=http://www.youtube.com/watch?v=WcsqA4ncnzYoi-zuki[/url] [watch near the very end]) a long step forward.
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12-07-2009, 10:53 AM | #10 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: 'Shotguns have dkb/dbt' - where did that myth (?) come from?
A well-delivered punch involves torso muscles, but the actual impact mass is much smaller. Essentially, a punch uses a mechanism very similar to a whip crack to transfer rotational energy generated in the hips and torso into hand velocity, but the mass which is actually relevant for knockback purposes is only the hand and for some types of strike the forearm.
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Tags |
blunt trauma, knockback, myth, shotgun |
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