Knockback and Bullets

[mudpyr8]

Another Mythbuster test.

They tested handguns (inlcuding .44mag), rifles, and a 12g shotgun (slug) against a 180lb dead pig hanging by a hair on a metal hook (tap with a finger was enough to knock it off).

None of them except the shotgun were able to dislodge the pig. Even the shotgun only knocked it off... the high-speed camera showed no appreciable knockback.

They even used fully automatic weapons - no effect.

I know gun experts have been saying such things for a long time, and knockback is a lot of fun, but it is also nice to have some demonstrable experimentation to witness in support of scientific fact.

Not suggesting to eliminate knockback in any fashion, just that for realists and cinematic realists engaging in simulated gunplay it's nice to witness the reality.

Just sharing -- FYI.

[gojira]

You'd have to change ALL the points costs of all guns to add the Does No Knockback Lim. Not a pretty picture. But maybe it can be added to.... REVISION 6!!!!

[Edsel]

I have read some interesting stuff on this subject. Several studies have shown that no handgun is physically capable of generating enough force to actually knock someone off their feet, much less back. Yet, there are many recorded accounts of guns knocking people down. One theory is that most civilized people are very aware of how deadly guns are that they instinctively flinch back from the gunshot as they are hit thus generating the illusion that the bullet has knocked them back. This might account for many of the early accounts of native warriors who seemed invincible and would charge whether or not they were shot. They did not have this learned fear of guns and so did not flinch away from the gun when they were hit. This may also explained why those on a high (drugs, etc.) often don't fall down immediately when shot.

[Frenchman]

Tell me the results of the study when they have Grond punch the pig.

[Black Lotus]

Knockback isn't caused by the force of bullets in real life.

When it DOES happen, it's the body trying to escape from the attack, even though it's already been hit by the bullets. A muscle spasm, if you will. Thus, dead pigs won't get "knocked back".

It's really hard to "knock someone back" without explosive force, 'cause people are pretty heavy, even in comparison to how much force even a strong person could muster with a baseball bat or a mace. A Major League slugger that hits someone with a bat might cause some serious damage, but the person wouldn't move an inch unless he falls or jumps on his own.

[Roy_The_Ruthles]

isn't that why bullets have the "beam" limitation (-1/4)?

[Black Lotus]

isn't that why bullets have the "beam" limitation (-1/4)?


No, that just means you can't "Spread" the attack, you can't blow doors off their hinges or do large patches of damage, and you cannot reduce the amount of damage you do with the attack (by declaring you want to do less damage).

Shotguns can Spread.

[Roy_The_Ruthles]

yep, i just read beam, it doesnt' mean no-knockback

[Dr Divago]

You'd have to change ALL the points costs of all guns to add the Does No Knockback Lim. Not a pretty picture. But maybe it can be added to.... REVISION 6!!!!I think this is no necessary...
IMHO in all more "realistic" Dark Champions (or DC-like) campaign Knockback is'nt used, and sometimes ever Knockdown is'nt used too

In more "cinematic" campaign like Champions or Champions-like, firearms are way muuuch more rarely seen, and aven in this case: is a superheroic genre, does not necessary be "realistic", it must be "cinematic" :cool:

[Black Lotus]

I think this is no necessary...
IMHO in all more "realistic" Dark Champions (or DC-like) campaign Knockback is'nt used, and sometimes ever Knockdown is'nt used too

In more "cinematic" campaign like Champions or Champions-like, firearms are way muuuch more rarely seen, and aven in this case: is a superheroic genre, does not necessary be "realistic", it must be "cinematic" :cool:

I believe knockback is still pretty realistic, since people do sometimes jerk around/ have spasms/ fall backwards/ etcetera when hit.

Of course, realistically, you WOULDN'T need the No Knockback Limitation in a realist campaign, because in reality -- it's more-or-less impossible to knock someone back, unless you Throw them, so Knockback wouldn't even exist. Of course, Move Throughs would have to be altered to fit a realistic campaign.

Actually, if I'm not mistaken, FREd says that Knockback is normally only used in Superheroic games... just something I remember from the Knockback rules section.

[Dr Divago]

Actually, if I'm not mistaken, FREd says that Knockback is normally only used in Superheroic games... just something I remember from the Knockback rules section.AFAIK i confirm it...

[Zed-F]

Heroic rules use Knockdown, not Knockback, by default. Knockdown rules don't cause people to fly huge distances, but does simulate the 'take a couple steps back and fall down' flinching away from the attack kind of thing.

[Black Lotus]

Heroic rules use Knockdown, not Knockback, by default. Knockdown rules don't cause people to fly huge distances, but does simulate the 'take a couple steps back and fall down' flinching away from the attack kind of thing.

Oh right, Knockdown. That's right, that must be what's required for taking only 1/2 damage with Move Through.

[Tech]

Tell me the results of the study when they have Grond punch the pig.

:lol: Well, last I heard, the French newspaper was wondering where the flying carcas of a dead pig crashing on top of a street cafe' came from.

[bigdamnhero]

I don't think knockback was ever intended to be realistic - it's a genre thang. :)

If you think about it from a conservation-of-momentum perspective, the force of the recoil of the gun is basically equivilent to the force of the bullet impacting on the other end. (Excepting high-tec recoil reduction mechanisms.) It's the fact that the impact is focused on such a small spot that gets you. I know people who've been shot and didn't even notice it until someone pointed out the blood. I know other people who've fallen down after taking a shot to the vest that didn't even leave a bruise. So it would seem fair to call it a psychological reaction rather than a physical reaction. (Hmm.. resist using EGO instead of STR...?)

[Fox1]

If you think about it from a conservation-of-momentum perspective, the force of the recoil of the gun is basically equivilent to the force of the bullet impacting on the other end.

Not true by the way. Recoil is a complex matter.

In addition to the momentum of the bullet you also have the jet of gasses escaping from the barrel, for a *very* brief period this can add hundreds of pounds of force. Using the traditional recoil formulas, it basically doubles the felt recoil. This by the way is the energy muzzle breaks are intended to use and counter by means of redirection.

On the other side of the coin, the weapon absorbs a significant amount before it reaches the firer.

And just to add a side note, most of the energy actually created in touching off a round is lost- only about 30% of it is transferred into bullet velocity.

[prestidigitator]

How's this?

Knockback/Knockdown is Psychological (-1/4 Limitation)
Anyone who has a Weapon Familiarity with the Broad Group this weapon belongs to, and/or an applicable Knowledge or Professional Skill, may make an Ego roll to avoid all Knockback or Knockdown effects from the limited Power. Such a roll may also be allowed in circumstances the GM deems appropriate, such as when the target is on certain psychedelic drugs.
:)

[Black Lotus]

How's this?

Knockback/Knockdown is Psychological (-1/4 Limitation)
Anyone who has a Weapon Familiarity with the Broad Group this weapon belongs to, and/or an applicable Knowledge or Professional Skill, may make an Ego roll to avoid all Knockback or Knockdown effects from the limited Power. Such a roll may also be allowed in circumstances the GM deems appropriate, such as when the target is on certain psychedelic drugs.
:)

ROFL... that's great.

[bigdamnhero]

Not true by the way. Recoil is a complex matter.

Well, if you want to get technical about it... :winkgrin: I was just trying to paint a very rough analogy, ie - KE of recoil small, KE of bullet can't be orders of magnitude larger. But I probably should've been more precise in my language. Or at least started out with the disclaimer that I was a history major, not a physics major. :D

[prestidigitator]

Well, if you want to get technical about it... :winkgrin: I was just trying to paint a very rough analogy, ie - KE of recoil small, KE of bullet can't be orders of magnitude larger. But I probably should've been more precise in my language. Or at least started out with the disclaimer that I was a history major, not a physics major. :D
Actually his arguments do nothing but affirm your statement. All the effects he mentions contribute to a higher momentum transfer (a.k.a. impulse) to the shooter ("recoil") than to the target. This difference must exist in any case by the second law of thermodynamics; the interesting thing is that it sounds like it is pretty significant in magnitude.

[Fox1]

Actually his arguments do nothing but affirm your statement. All the effects he mentions contribute to a higher momentum transfer (a.k.a. impulse) to the shooter ("recoil") than to the target. This difference must exist in any case by the second law of thermodynamics; the interesting thing is that it sounds like it is pretty significant in magnitude.

Exactly. In pure energy terms, guns are worse on the shooter than the target.

But energy doesn't tell the whole story. Something that won't budge a person (say a .30-06) is still capable of blowing a hole in over 3/4" of steel.

[prestidigitator]

Exactly. In pure energy terms, guns are worse on the shooter than the target.

But energy doesn't tell the whole story. Something that won't budge a person (say a .30-06) is still capable of blowing a hole in over 3/4" of steel.
Oh, certainly. But the point is that Knockback moves a whole target, and must therefore really be a significant transfer of momentum (unless there is some psychological and/or physiological help from the target, or some dramatic or metaphysical principle of the game setting involved). We aren't talking about the ability to penetrate the target (although if we really did want to include that in our discussion, more penetration will also tend to decrease the transfer of momentum; that is probably handled adequately already by the extra die used to resolve Killing Attack Knockback).

[Fox1]

Oh, certainly. But the point is that Knockback moves a whole target, and must therefore really be a significant transfer of momentum (unless there is some psychological and/or physiological help from the target, or some dramatic or metaphysical principle of the game setting involved).

Very true. As the momentum required to move a person doesn't even exist to transfer, there can be no knockback as it's commonly thought of. That's a given for anyone who understands the basics of physics.

[bigdamnhero]

Very true. As the momentum required to move a person doesn't even exist to transfer, there can be no knockback as it's commonly thought of. That's a given for anyone who understands the basics of physics.

Right, which was what I was trying to say, but much better put. :)

[SuperKlaus]

Well, isn't the reduced KB for Killing Attacks enough to (usually) stop a gun from knocking someone back anyway? A typical handgun does 2d6 BODY, which is up against 3d6 to figure KB...

The way I see it, the rules do a fine job of keeping down unrealistic small-arms KB while still allowing superhero-style lasers and such with half a dozen Killing d6s to blast people across the room.