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Neon Knight
2007-07-11, 01:50 PM
This about D20 Modern, for the 4 of you forum goers out there that actually play it.

I was sitting back in my chair yesterday, preparing for a new game, when I realized I had never made a character that used a shotgun as his main weapon. Shrugging, I decided to make on. Why not?

I quickly found out why not. Shotguns are sub-par weapons under the current rules. They do no more damage than your average assault rifle, have poor range, and suffer attack and damage penalties for range. What's a boomstick fan to do?

I was wondering if the few frequent D20 modern players on these boards had any solutions to this quandary. I was considering upping the damage dice on shotguns, but that just didn't seem to be a good solution.

And while we are on the subject of dysfunctional weapons, what's up with machine guns? According to the Weapons Locker book, they overheat after 5 rounds of autofiring. And yet they don't get any bonuses for autofiring and don't use up more than 10 bullets. There is simplification, and then there is just plain dysfunction

So, anyone have any easy answers?

Matthew
2007-07-11, 01:56 PM
Sadly, D20 Modern Gun Rules are pretty sucktastic, in my opinion. I think I would end up changing a lot of the underlying ideas about Auto, Burst and Single Shot, not sure how helpful that would be to you, though.

Neon Knight
2007-07-11, 02:00 PM
I pretty much agree. I'd be open to massive revamping of the rules myself. Burst I had no problem with, but autofire always struck me the wrong way.

Joran
2007-07-11, 02:08 PM
Sawed-off shotguns can double tap without the feat; since they're based off of the standard side-by-side shotgun. Pull both triggers at once, tada, double shot.

Other than that, there's no real reason to use a shotgun, except for flavor. Also, if your GM allows it, you can use all sorts of special load ammo in one as well (bean bag, tear gas, door breaching).

P.S. Shotguns in the real world aren't particularly great weapons, lethality-wise.

....
2007-07-11, 02:11 PM
P.S. Shotguns in the real world aren't particularly great weapons, lethality-wise.

:haley: "Don't you EVER say that to me again!"

Attilargh
2007-07-11, 02:26 PM
P.S. Shotguns in the real world aren't particularly great weapons, lethality-wise.
They should be a bit easier to hit with, though. I'm not exceptional shot, and I can hit a flying clay disk now and then. With a pistol or a rifle, I probably couldn't.

Lemur
2007-07-11, 02:26 PM
If you have the Weapons Locker or take a look at some of the (non-FX) equipment in the Arcana section of the SRD, shotguns can accomodate a variety of special ammunition types that ordinary guns can't use. So a shotgun can be sort of a "utility kit" type of gun.

Neon Knight
2007-07-11, 02:28 PM
P.S. Shotguns in the real world aren't particularly great weapons, lethality-wise.

Everything I've read seems to speak the opposite. A shotgun in close range combat is a thing to be feared for its great potential in inflicting harm. Kevlar vests and range greatly decrease this, but against unarmed target in close quarters all my knowledge and experience, and the experience of several officers of the law who I have spoken with seem to state that the opposite of your statement is true.

To put things in perspective, take the 5.56mm NATO round. Its civilian counterpart, the .223 (the 5.56 and .223 are so close that a 5.56 weapon can shoot .223s without a problem. The opposite is not true due to gas pressure differences) is not rated high enough to take down deer reliably. It is illegal to hunt deer with it, as it would wound the animal and generally make its end cruel.

The most common shotgun round is 00 buckshot. Its purpose is clear. If you can kill a deer with a 12 gauge shotgun, you can kill a man with it.

SWAT teams use them to clear buildings. The military uses them for a similar purpose. shotguns have been developed that can be slung under the barrel of an M16. The military has funded the development of fully automatic shotguns.

All I see is a bunch of evidence pointing to a highly effective close combat weapon.

Joran
2007-07-11, 03:03 PM
All I see is a bunch of evidence pointing to a highly effective close combat weapon.

With a few caveats. Shotguns have great stopping power, but poor penetration; this leads to problems if the target is armored. They also have poor range. Automatic shotguns really haven't penetrated into the military in any large numbers. In general, front-line soldiers are given an assault rifle and a pistol side-arm.


shotguns have been developed that can be slung under the barrel of an M16

Correct, but not as a lethal weapon. The MasterKey is primarily used as a door breaching weapon.


The most common shotgun round is 00 buckshot. Its purpose is clear. If you can kill a deer with a 12 gauge shotgun, you can kill a man with it.

True, but with a high-powered hunting rifle and some good aim, you can take out the deer from much further away. As an aside, the thing that bothers me about the d20 Modern rules is that a hunting rifle at close range is the same as a shotgun. In d20 Modern, you could use a rifle for clearing a room with no penalties =P

Shotguns are great home defense weapons and police weapons. However, most of the time, a compact assault rifle will be more effective. They're not the superweapon that FPS make them out to be.

P.S. To be honest, I was thinking of bird-shot when I first said "not that great". Think the stuff that our esteemed Vice President shot a man with.

Swordguy
2007-07-11, 03:07 PM
Use the rules for Shotguns in Spycraft. Much, MUCH better.

Skjaldbakka
2007-07-11, 03:21 PM
Use the rules for Shotguns in Spycraft. Much, MUCH better.

Obviously you can't quote what those are, but could you give us an idea? I've palyed a Spycraft Demo, which was awesome, but never been in a long-running game.

Swordguy
2007-07-11, 03:38 PM
Obviously you can't quote what those are, but could you give us an idea? I've palyed a Spycraft Demo, which was awesome, but never been in a long-running game.

Better-than assault rifle-scale damage, plus knockdown, ability to hit multiple targets with a wide choke setting, burst-fire rules for combat shotguns (such as the Mk.III Pancor Jackhammer), and a little more.

More specifically, an assault rifle will do 4d4 damage (+1 or +3 depending on the type of burst, narrow or wide). A .50 BMG round does 2d12+2. A shotgun will do in the 5d4 to 2d12 region (depending on shell gauge) before any other modifiers are added, such as burst fire or ammo types. And, again, pretty much all shotguns have the Knockdown quality. You have to get into handgun calibers of bigger than .45 ACP for that.

In addition, the general firearms rules in Spycraft (they're also reprinted in the Stargate SG-1 RPG) are superior to d20 Modern by a LOT.

Skjaldbakka
2007-07-11, 03:53 PM
I know this will kill cat girls as I am typing this. DIE! DIE! DIE!

However, I don't think shotguns should have knockdown. Physics says no. The kick on the receiving end of a shotgun is going to be less than the recoil (the force is the same, and distance to target is farther). Knockdown via "and now you're dead not-withstanding".

Especially since with hitpoints, you aren't getting hit full-blast with the shotgun- that would kill you. If it doesn't kill you, you're just getting winged (ah, HPs).

EDIT- and I don't even like physics.

Neon Knight
2007-07-11, 05:15 PM
Joran: You are correct, and some of your points (I mentioned kevlar, and range is a no-duh) were even addressed in my own post. I was referring to the XM26 LSS, which is a lethal weapon. http://en.wikipedia.org/wiki/XM26_Lightweight_Shotgun_System

With the every increasing frequency of personal armor on the battlefield, shotguns will probably fall out of favor entirely, at least on the conventional battlefield. SWAT teams and police officers will continue to use them for building clearing until criminals get kevlar hides.

You mentioned one of my other beefs with D20 Modern rules. The only penalty related to weapon length is that longarms have a -4 attack penalty against adjacent targets. That's it.

Swordguy: What is this Spycraft, and where can I get it?

If anyone else has any other suggestions I would be happy to hear them.

EDIT: Apparently, with certain chokes, shotguns can get effective range of up to 75 yards. And they supposedly have a hit probability 45% higher than that of machine guns and twice that of assault rifles. Each piece of shot, of course, is about as effective as a pistol round, but it is something to consider.

The above information was drawn from the Joint Service Combat Shotgun .pdf document created by the U.S. army, Joint Service Combat Shotgun reports, and a study compiled by the British in action from Borneo in the 1960s.

No shotgun will ever match the accuracy and range of a rifle. Most FPSs, however, shortchange shotguns by limiting their effective range to a few feet. This is, apparently, not the case.

Mike_G
2007-07-11, 05:23 PM
To model shotgun damage well, it should be very high damage at close range, decreasing with each range increment.

Shot will rip you up at close range, but rapidly loses velocity.

It should have a big bonus to hit over a rifle at close range as well, and that should decrease with range.

Hmmmmmmmm....

Maybe give it a really short range increment, a circumstance bonus to hit and high damage, both of which will decrease with each range increment.

This will make if better than a rifle at close range, and worse at long range, which is exactly as it should be.

Swordguy
2007-07-11, 06:29 PM
I know this will kill cat girls as I am typing this. DIE! DIE! DIE!

However, I don't think shotguns should have knockdown. Physics says no. The kick on the receiving end of a shotgun is going to be less than the recoil (the force is the same, and distance to target is farther). Knockdown via "and now you're dead not-withstanding".

Especially since with hitpoints, you aren't getting hit full-blast with the shotgun- that would kill you. If it doesn't kill you, you're just getting winged (ah, HPs).

EDIT- and I don't even like physics.

The knockdown simulates the massive shock of being struck in many places with the shot, or the massive trauma of the slug, IIRC. It's not just "the shell bowls you over."

Spycraft is a "semi-" out-of-print variant on d20 3.5 produced by AEG. It's notable for good firearms rules in general and the first d20 variant to use wound/vitality in its core mechanic. It is meant to model...well...spies. The idea is that of a slightly more "gritty" James Bond (think the new Casino Royale edition).

http://www.alderac.com/

Burrito
2007-07-11, 06:34 PM
Actually, the most common type of deer hunting round is a slug. Many states no longer allow buckshot for deer because it isn't very lethal. A decent 12 guage with a slug barrel, top quality slugs and scope can reach out and touch someone (lethally) at up to 200 yards. 00 buckshot is pellets about the size of a pea, and each 12 guage shell has about a dozen of them. Even a heart or lung hit with these will not be immediatly lethal. Most level 3 body armor will stop either slugs or shot.

Eldmor
2007-07-11, 06:55 PM
For my d20M games, here's what I do with shotguns.


Increase Damage Die Type by One
-1 Damage Penalty per Range Increment
No Longarm Penalty


Pretty simple.

Swordguy
2007-07-11, 07:24 PM
Most level 3 body armor will stop either slugs or shot.

That is misrepresenting things significantly. While the soft slug won't often "penetrate" soft body armor of the type you evidently describe, the impact will shatter bones, collapse lungs, and stop the heart. It's still a massive hunk of lead, about the size of a 0.50 BMG (assuming 12 ga slugs) traveling at high velocity. That energy (if not the slug) will go straight through the armor.

As for shot - yes. Soft body armor will often stop individual shot. However, there's going to be enough spread at all but the narrowest chokes and shortest ranges that a pellet or two will end up somewhere that isn't protected.

Falkus
2007-07-11, 07:33 PM
Spycraft is a "semi-" out-of-print variant on d20 3.5 produced by AEG. It's notable for good firearms rules in general and the first d20 variant to use wound/vitality in its core mechanic. It is meant to model...well...spies. The idea is that of a slightly more "gritty" James Bond (think the new Casino Royale edition).

Spycraft 2.0 is the new version, released about a year and a half ago, I think. It's my favorite roleplaying system right now.

http://www.crafty-games.com/

Joran
2007-07-12, 01:07 AM
I was referring to the XM26 LSS, which is a lethal weapon. http://en.wikipedia.org/wiki/XM26_Li...Shotgun_System

hehe, that looks both silly and very badass. Sadly, it's not automatic.

Looks like I was mistaken about shotguns not being lethal, at least in certain situations with certain types of ammo. When I made that point, I was thinking bird shot.

Here's a concept that looks fairly interesting.
http://en.wikipedia.org/wiki/LeMat_revolver

It's basically a revolver with a second barrel containing a shotgun shell. Other than difficulties in reloading it, any reason why this never took off? Recoil perhaps?

Dervag
2007-07-12, 01:13 AM
As an aside, the thing that bothers me about the d20 Modern rules is that a hunting rifle at close range is the same as a shotgun. In d20 Modern, you could use a rifle for clearing a room with no penalties =PWell, in practice the shotgun doesn't have enough spread to hit multiple targets with one shot, so you need at least one shot per target.

If a rifle can bring down the people you're clearing out of the room with one shot, and a shotgun can do so too, and they have the same rate of fire, there's no reason why shotguns would be superior to rifles for clearing the room. High-powered hunting rifles are traditionally bolt-action, which makes them unsuitable for close combat in the modern era, of course. But unless d20 Modern makes a clear distinction between semi-automatic and bolt-action firearms, the rifle shouldn't be substantially inferior to the shotgun for close combat.


You mentioned one of my other beefs with D20 Modern rules. The only penalty related to weapon length is that longarms have a -4 attack penalty against adjacent targets. That's it.What other penalties should they have? The longarm close combat penalty makes it hard to shoot anything within about 5-7 feet already; what else do you need and why?

Swordguy
2007-07-12, 01:31 AM
The difference being that if you spray a room with automatic SMG fire, you'll probably have at least a few wounded OPFOR who can fight back. If you spray a room with automatic shotgun fire, you're going to be looking at a lot of red mist (and probably a lot of holes in the ceiling).

Seriously, bursts of shotgun slugs tear apart targets like nobody's business.

Fawsto
2007-07-12, 08:33 PM
Take some ideas from whitewolf storyteller games, like Mage, Vampire and Werewolf. Indeed they don't have much in common with d20 in any ways, but they get a nice overlook on gunfighting. Theyr ideas on burst, full auto and single shots are pretty good... The only problem I found there was the fact that you can't benefit from bonuses for firing at extremely short ranges with a shotgun.

horseboy
2007-07-12, 08:44 PM
The difference being that if you spray a room with automatic SMG fire, you'll probably have at least a few wounded OPFOR who can fight back. If you spray a room with automatic shotgun fire, you're going to be looking at a lot of red mist (and probably a lot of holes in the ceiling).

Seriously, bursts of shotgun slugs tear apart targets like nobody's business.

Especially if using Flechette rounds. :smallsmile:

But with an open choke you could hit multiple targets, you just wouldn't hit them as hard if you were using a modified choke. So to do that, it would be feasible to split the total damage between the two targets.

Golthur
2007-07-12, 10:14 PM
To model shotgun damage well, it should be very high damage at close range, decreasing with each range increment.

Shot will rip you up at close range, but rapidly loses velocity.

It should have a big bonus to hit over a rifle at close range as well, and that should decrease with range.

Call of Cthulhu BRP models shotguns similar to this:

A 12-gauge shotgun does 4d6/2d6/1d6 damage at 0-10/11-20/21-50 yards when using shot (rules for slugs are different). Keep in mind that in CoC BRP, your average character has about 11 or 12 HP.
Shotguns, unlike other firearms, do not suffer any range penalties for accuracy unless it's outside of the maximum range of the shotgun (with normal firearms, your chance to hit halves with each range increment - e.g. if you had 40% at 1 range increment, you'd have 20% at 2, and 10% at 3).
I usually add an unofficial ruling that the effectiveness of body armour is doubled against shotguns. Yeah, it's purely arbitrary :smile:


Similar rules could be adopted for d20 - e.g. decreasing damage dice with range, reduced range penalties to simulate the spreading effect of the shot - or possibly the ability to strike several adjacent targets with the same attack roll.

Dervag
2007-07-13, 12:47 AM
The difference being that if you spray a room with automatic SMG fire, you'll probably have at least a few wounded OPFOR who can fight back. If you spray a room with automatic shotgun fire, you're going to be looking at a lot of red mist (and probably a lot of holes in the ceiling).

Seriously, bursts of shotgun slugs tear apart targets like nobody's business.Yes, but that only works if you're carrying an automatic shotgun, which you likely aren't (yet).

Since normal shotguns of today are not automatic, why are they dramatically superior to other long arms of equal rate of fire for room-clearing?

blue chicken
2007-07-13, 01:10 AM
Um...hm. I'm not so into D20 modern, but I am into firearms, and that last question strikes me a bit oddly.

Consider the type of people who conduct "room-clearing" exercises. In most cases, you're talking trained professionals, possibly in a hostage situation. These are the types of folks who are trained to pick their shots, not spray the whole room with fire of any sort.

Edit: As for shotguns not being automatic. Even if they aren't...a combat shotgun is going to have a round capacity between 8-16 rounds, depending on what kind of extended clip you have...maybe not so much the police models, but even five shotguns shells in a weapon is enough to do a stupendous amount of damage. Of course, some combat shotguns have drum magazines or stick clips that let them hold far more than five rounds, so...either way. Just because something isn't automatic doesn't mean it's pump-action. Semi-auto works wonders.

A shotgun is superior in close combat because...well, think about it. You're adrenalated, confused, rushing...it's close combat. Even if you are a professional trained to pick your target, the fact remains that it's easier to hit someone with a small cloud of lethal pellets than it is with individual rounds from a rifle. And there's also the inherent fact that getting hit by even PART of a shotgun blast...will ruin your day. World War Two, for instance. Allied soldiers sometimes reported hitting enemy soldiers two, three, four times with small-caliber fire...and their attackers didn't stop. When you're fighting someone ELSE who's keyed-up and bent on killing you, what you want is single-trigger-pull knockdown power. And not many people are going to be getting up if they take a cloud of lead balls to the chest from ten yards away. You're practically guaranteed to hit at least one thing that's vital, even if you don't kill your target right away. They're down for the count.

horseboy
2007-07-13, 01:39 AM
Yes, but that only works if you're carrying an automatic shotgun, which you likely aren't (yet).

Since normal shotguns of today are not automatic, why are they dramatically superior to other long arms of equal rate of fire for room-clearing?

They do make automatic shotguns. They're hideously illegal. I remember back around '90 that a classmate came in with a copy of Guns&Ammo with an article about the Remington's (I believe it was) Street Sweeper. Then came the USAS 12.

Jops
2007-07-13, 02:01 AM
I home-ruled the shotguns in D20 Modern. I made their damage 3d6 / 2d6 / 1d6 depending on range. They deal 3d6 at point-blank (that'd be 3 meters / 10 feet / 2 squares away), 2d6 'till 9m / 30ft / 6 squares and only 1d6 after that, but with the possibility to hit targets adjacent to the line of fire (tho they have a +4 bonus to AC).
This going with the assumption that shotguns always fire a rose of pellets.

Can't say much about machineguns, never used them.

vrellum
2007-07-13, 08:01 AM
I know this will kill cat girls as I am typing this. DIE! DIE! DIE!

However, I don't think shotguns should have knockdown. Physics says no. The kick on the receiving end of a shotgun is going to be less than the recoil (the force is the same, and distance to target is farther). Knockdown via "and now you're dead not-withstanding".

Especially since with hitpoints, you aren't getting hit full-blast with the shotgun- that would kill you. If it doesn't kill you, you're just getting winged (ah, HPs).

EDIT- and I don't even like physics.

Actually the impact at the receiving end is going to be considerably greater than the recoil. Here's why:

The projectile is accelrated down the length of the barrel, which is probably around 26" long. That gives a lot of time and distance for the shot to reach their maximum velocity and results in a recoil that is somewhat of a push. When they strike their target, they stop after traveling a few inches. That results in more of a "hit".

Also, the shooter has the gun against his shoulder and is braced for the recoil. The same usually can't be said for whatever is getting shot.

Jops
2007-07-13, 08:03 AM
and two catgirls have just died...:smallfrown:

Irenaeus
2007-07-13, 09:57 AM
Actually the impact at the receiving end is going to be considerably greater than the recoil. Here's why:

The projectile is accelrated down the length of the barrel, which is probably around 26" long. That gives a lot of time and distance for the shot to reach their maximum velocity and results in a recoil that is somewhat of a push. When they strike their target, they stop after traveling a few inches. That results in more of a "hit".

Also, the shooter has the gun against his shoulder and is braced for the recoil. The same usually can't be said for whatever is getting shot.

I will admit that I really don't know much about what I'm talking about here, but this sounds very strange to me. Won't the pellets continue to add to the felt recoil all the way while it travels down the barrel? Also, from the moment the shot exits the barrel the pellets will start do deaccelerate at a much higher rate than a rifle bullet because of their abysmal ballistics, decreasing their force and felt impact.

The person being hit may not have braced for any impact, but I would assume he is not any more likely to be knocked over by the impact than anyone accidentaly pulling the trigger of a loaded shotgun. He might keel over from being dead after a quite short time, though.

Anybody know any physics here? If so, would you care to enlighten me.

blue chicken
2007-07-13, 10:07 AM
Law of Conservation of Energy. The impact of a shotgun blast, if anything, is less than that of its recoil. The full force the chemical and kinetic energy propelling the slug or pellets out of the rifle is transferred through the stock of the weapon and into the shooter's body. The ammunition, on the other hand, does indeed start to lose energy as soon as it's fired, and by the time it hits someone...the only reason they fall down is from crippling pain and/or severe deadness.

...don't yous folk watch Mythbusters...?

Attilargh
2007-07-13, 10:12 AM
According to Newton, the force which propels the shot out of the barrel (and is then transferred to the target upon impact) is equal to the force which propels the gun backwards.

Our good friends Jamie and Adam have provided us with empirical evidence (http://www.youtube.com/watch?v=QCzD5uhSViY) supporting mr. Newton. Twice.

Irenaeus
2007-07-13, 10:12 AM
Law of Conservation of Energy. The impact of a shotgun blast, if anything, is less than that of its recoil. The full force the chemical and kinetic energy propelling the slug or pellets out of the rifle is transferred through the stock of the weapon and into the shooter's body. The ammunition, on the other hand, does indeed start to lose energy as soon as it's fired, and by the time it hits someone...the only reason they fall down is from crippling pain and/or severe deadness.

...don't yous folk watch Mythbusters...?

Thank you, that's what I thought.

...and I do.

Edit: Thanks for the link, Attilargh. Great fun.

Truwar
2007-07-13, 10:20 AM
Yes, the pellets do slow down but the impact of each pellet in concentrated in an area the size of, well a pellet. The person firing the weapon has a nice heavy shotgun to absorb all of that impact, not to mention that nice padded stock snugged up against his shoulder.

Besides getting knocked down by a bullet is not purely a process of being lifted off your feet and slammed into the ground by the sheer velocity of the bullet. When your body is terribly perforated (say, for example by a 12 gauge shotgun blast of buckshot at close range) it goes into shock and will often collapse as a result. The idea of a person being flung through a window by a shotgun blast may be a bit far fetched but someone being knocked down by said blast is very reasonable.

Also, at close range, a shotgun slug has more than enough power to punch through most modern armor. Of course stopping the shell from penetrating your body might not protect you from being turned to jelly by the impact of said slug…

Attilargh
2007-07-13, 10:25 AM
When your body is terribly perforated (say, for example by a 12 gauge shotgun blast of buckshot at close range) it goes into shock and will often collapse as a result.
One is probably not going to get up from that in six seconds, which kinda implies this is an issue better represented by the hit point system than any knockdown rule.

vrellum
2007-07-13, 11:08 AM
Yes, the pellets begin to slow down as soon as they leave the muzzle of the gun. But most people are forgetting an important point.

The pellets are being pushed by the burning powder down the length of the barrel. They are accelerating over the full 20+ inches of the barrel and thus they have a relatively long time to reach their maximum velocity. That means that the force pushing on the gun (which is heavy) is drawn out over a long time.

Force (F) = mass (m)*acceleration(a)
velocity = acceleration * time
accelaration = velocity/time

Which takes longer, pellets to accelerate 20+ inches down a barrel or pellets to come to a stop while penetrating about 4" into a target?

I think we can agree that if the pellets are traveling at about the same velocity when they hit as when they were fired (and they will be if the target is close) it takes less time for the pellets to travel 4 inches than it does for them to travel 20 inches.

Therefore the accelaration is greater when the pellets strike their target than when they are fired. Thus the force hitting the target is greater than the force hitting the person who shot the gun.

edit: However, I don't really know what the knock down rules do in d20 modern. The impact will not lift someone's feet off the ground and throw them into a wall. So the knockdown rules of d20 modern may not be at all realistic (they probably are not). However, the force of the impact is greater than the force exerted on the person firing the weapon.

Skjaldbakka
2007-07-13, 11:20 AM
As for knock-down do to 'getting hit with a shotgun really sucks' factor- that isn't the case either.

HP system people! If I take 20 damage from a shotgun blast, and I have 80 hp, I wasn't hit in the gut by the shotgun blast. At best, the pellets scored my leg or shoulder. On the other hand, if I have 30 HP, taking 20 dmg from any source should qualify for 'knockdown due to the trauma caused by the injury'. It shouldn't be a shotgun specific trait, it should be a damage specific trait. Very much the clobbered variant (if you take more than 1/2 your current hp from one attack, you can only take a standard action this round- or in this case, you fall prone).

Irenaeus
2007-07-13, 11:34 AM
Snip
Aha, so you mean that the felt force on the target, while being an almost identical amount of force that hits the shooter, is absorbed by the target at much less time than by the shooter?

But won't the difference be miniscule? At 20 ft., the whole process from the trigger is being pulled and until the pellets are lodged in the target will take, and I'm guessing here, less than one-fifthieth of a second, won't it? I suppose you don't need a lot of distance between the shooter and the target before the force excerted on the target becomes lesser that the one excerted on the shooter.

Edit: I agree 100% to the post above, btw. This should be an effect of damage in general, not just of shotguns.

blue chicken
2007-07-13, 11:40 AM
Does anyone have the formula for momentum handy?

And also, so we're sure, we're talking about pellets, not slugs, right? Big difference.

And the force on the target, absolutely, quantitatively, can't be greater than the force of the shotgun. You'd be generating energy; it just won't happen. Perhaps you're talking about IMPULSE? I'm not as clear there, but it's the same scenario. And keep in mind...it's not an elastic collision when pellets strike flesh. They don't transfer their kinetic energy to the victim like a beanbag round would. Instead, they penetrate in, slowing, like you said, transferring some of their movement energy, but losing a lot of it in the penetration.

Attilargh
2007-07-13, 11:41 AM
Force (F) = mass (m)*acceleration(a)
velocity = acceleration * time
accelaration = velocity/time

Which takes longer, pellets to accelerate 20+ inches down a barrel or pellets to come to a stop while penetrating about 4" into a target?
You forget friction, which is another force directly opposite to the force accelerating an object. Thus, the force moving the pellets out of the barrel is F = (m[v/t] - F1), whereas the force stopping those same pellets is F = (m[v/t] - F2). It should balance out.

Swordguy
2007-07-13, 12:16 PM
As for knock-down do to 'getting hit with a shotgun really sucks' factor- that isn't the case either.

HP system people! If I take 20 damage from a shotgun blast, and I have 80 hp, I wasn't hit in the gut by the shotgun blast. At best, the pellets scored my leg or shoulder. On the other hand, if I have 30 HP, taking 20 dmg from any source should qualify for 'knockdown due to the trauma caused by the injury'. It shouldn't be a shotgun specific trait, it should be a damage specific trait. Very much the clobbered variant (if you take more than 1/2 your current hp from one attack, you can only take a standard action this round- or in this case, you fall prone).

Again, I point to Spycraft - a Wound/Vitality system. What's more...ONLY PC's and "named" characters have Vitality. Mook NPCs have ONLY wound points - which means that a 5d4 damage shotgun is DEATH to a Con 11-12 mook.

About the Takedown rule for shotguns: you're generally being struck by a large mass of fast-moving lead above your center of gravity. That is going to result in a fall much of the time - regardless of what the lead does to you. In addition, it's not a GUARANTEED fall, as per the Spycraft Takedown rules. There's a check you have to make OR you go prone.

Regarding automatic shotguns: They tend to be military or SWAT-team-level ordnance. However, you can't possibly tell me that PCs won't manage (or want) to get their hands on that kind of toy. Hell, look at all the stories about PCs with explosives. Also, except at very long ranges, you're not hitting multiple opponents with pellets. IIRC, a wide choke setting is about a 10" diameter cloud at 30'. What shot DOES allow you to do is be a little less precise in your shooting and still hit somebody (reflexive firing means you don't have time to line up a perfect shot, and rifle fire requires you to either hit the enemy perfectly - as the bullet is very small - or go rock and roll and hold the trigger down, "walking" your fire onto the enemy).

Oh, and @ Bluechicken. You're absolutely wrong regarding who does room-clearance. Room clearance is "nice-speak" for "open the door, kill everything/body inside". Typically, how it works is as follows:

Open door, throw flash-bang inside (you want to save destructive grenades most of the time), close door. Grenade goes off.
Stack of 4 guys by the left side of the door (as you look at it from the outside). 1st guy opens the door, moves in, goes the the far right corner, and starts moving up the far right wall. 2nd guy goes behind him to the far right corner, 3rd guy goes to the far left corner, 4th guy moves in to the center of the room.

Whenever possible, the 1st guy has an automatic shotgun, something like a USAS-12 or an Armsel Striker 12 (some of the Jarheads got their hands on the Striker, and we hated them for it - such a wonderful weapon) . He's firing the length and width of the room as he moves, and typically just as he's run out of ammo and has to change magazines and the surviving (and suppressed) OPFOR get a bead on him do the other guys get in the room and perform targeted fire with SMGs, M4s, pistols, and the like. The role of the 1st guy can also be performed by someone with an automatic rifle (preferably something like an M249 SAW), but in that case he's going more for suppression and less for kills - again, because people can (depressingly often) shake off the effects of a small-caliber rifle hit.

What YOU'RE thinking about is room suppression. Get in, make them put their heads down, and get in there and force them to surrender because they're still trying to hear and see again and can't fight back.

Skjaldbakka
2007-07-13, 12:26 PM
Ah, W/V. In that case, takedown makes perfect sense- assuming you take wound damage.

Swordguy
2007-07-13, 12:33 PM
Ah, W/V. In that case, takedown makes perfect sense- assuming you take wound damage.

That is indeed how it works.

blue chicken
2007-07-13, 12:36 PM
Indeed, Swordguy. I was talking about situations where you don't WANT to kill everyone inside...in the case of room clearing, fire away, maestro.:smallbiggrin:

vrellum
2007-07-13, 02:34 PM
Does anyone have the formula for momentum handy?

And also, so we're sure, we're talking about pellets, not slugs, right? Big difference.

And the force on the target, absolutely, quantitatively, can't be greater than the force of the shotgun. You'd be generating energy; it just won't happen. Perhaps you're talking about IMPULSE? I'm not as clear there, but it's the same scenario. And keep in mind...it's not an elastic collision when pellets strike flesh. They don't transfer their kinetic energy to the victim like a beanbag round would. Instead, they penetrate in, slowing, like you said, transferring some of their movement energy, but losing a lot of it in the penetration.

The equation for momentum is M= mass*velocity

And the force on the target absoultely positively can be greater than the force on the shotgun. It is not related to energy

kinetic energy = 1/2*mass*velocity^2

The pellets do have less kinetic energy when they strike the target because they have been slowing down from the moment they left the barrel due to drag. So energy is conserved.

You asked about impulse as well. The impulse on the two are also different.

impulse = change in momentum, the equation is

force * time = mass * (change in velocity)

In fact, this probably demonstrates my point even clearer. The mass of the pellets is constant so we can write, where x = mass of pellets

force(shooter) * time(start)= x * (change in velocity)
force(target) * time(stop) = x *(change in velocity)

If the target is close to the muzzle then the velocity at impact is close to the muzzle velocity, which I will call Vmax. When fired the projectile goes from 0 to Vmax and the change in velocity is Vmax. When the projectile hits the target the velocity goes from Vmax to 0 and the change in velocity is -Vmax, so we can say

force(shooter) * time(start) = x*Vmax
force(target) *time(stop) = x*(-Vmax)

Thus we can substitute and we get

force(shooter) * time(start) = -force(target)*time(stop)

time(start) = the time it takes the projectile to leave the muzzle of the gun, so they need to travel about 24".

time(stop) = time it takes the projectile to come to a halt inside the body, with shot gun pellets, that's probably 4" to 6".

Thus the force on the target is considerably higher than the force on the shooter.

blue chicken
2007-07-13, 02:50 PM
Arrrg. I suppose I mistook "force" for "energy." Impulse I'll give you for sure; it's the same reason that a boxer pulling his head away from a punch can cut the force in half or more by lengthening the time of the deceleration. And the same reason paintballs hurt so much more when they bounce then why they splatter.

I'd still be interested to see some real, practical data on this. I like me some physics, but all of those equations just make me dizzy.

Seriously, though. Has no one seen that episode of Mythbusters? I thought everyone loved that show...

Joran
2007-07-13, 03:08 PM
Since normal shotguns of today are not automatic, why are they dramatically superior to other long arms of equal rate of fire for room-clearing?

This would require more information on shooting that I know (I've only been out on the firing range once and have no law enforcement training).

My guesses:

1) Rifles are longer than shotguns: In confined spaces, they might be more cumbersome. Also, since they are longer, they might take a fraction of a second longer to maneuver into firing position.

2) Time to acquire target: Do you have to aim shotguns as precisely as a rifle? if not, you might be able to get a good enough shot off more quickly. Do shotguns even have iron sights?

3) This only applies to Single RoF weapons (pump-action shotgun vs. bolt-action rifle): Once a shot is fired, I assume a pump-action shotgun can cycle the action much faster than a bolt-action rifle. Also, pumping the shotgun doesn't require moving the head away from sights, allowing the user to reacquire a target while pumping. Unless the user wants to whack himself in the head with the bolt, s/he needs to move their head away from sight to work the bolt, which requires more time to reacquire a target.

P.S. Anyone see anything wrong with what I just wrote?

Swordguy
2007-07-13, 03:31 PM
This would require more information on shooting that I know (I've only been out on the firing range once and have no law enforcement training).

My guesses:

1) Rifles are longer than shotguns: In confined spaces, they might be more cumbersome. Also, since they are longer, they might take a fraction of a second longer to maneuver into firing position.

2) Time to acquire target: Do you have to aim shotguns as precisely as a rifle? if not, you might be able to get a good enough shot off more quickly. Do shotguns even have iron sights?

3) This only applies to Single RoF weapons (pump-action shotgun vs. bolt-action rifle): Once a shot is fired, I assume a pump-action shotgun can cycle the action much faster than a bolt-action rifle. Also, pumping the shotgun doesn't require moving the head away from sights, allowing the user to reacquire a target while pumping. Unless the user wants to whack himself in the head with the bolt, s/he needs to move their head away from sight to work the bolt, which requires more time to reacquire a target.

P.S. Anyone see anything wrong with what I just wrote?

You're comparing shotguns to bolt-action rifles. Nobody uses bolt-action rifles for room-clearing unless they're suicidal. It's a non-issue. EDIT: unless they're got the old rifle-launched grenades that only fire off a BA rifle. But that's about the only way I can think of where you'd use one in this scenario.

Combat shotguns are in fact shorter than rifles, though they are much longer and heavier than SMGs or carbines. Their ammo weighs more as well.

Shotguns using shot have a slightly greater "ease" (for lack of a better term) than rifles. You can be a little off and still hit your target. Automatic rifle fire has a similar effect, in that it puts several rounds in an area in an effort to hit a single target with just 1 or 2.

Why use shotguns? They cause more damage to the body than anything else short of explosives. Hit someone with rifle fire. They'll be bleeding from 1 or 2 wounds, and will often be able to continue fighting (this happened a LOT in Iraq), mainly because rifle fire tends to overpenetrate (wasted energy). Hit someone with buckshot and they'll be bleeding from a whole lot of wounds, their torso will be shredded, and the odds of hitting something vital go up a lot more. Hit someone with a slug round and a significant portion of their torso will be gone. Basically, if you hit someone square with a shotgun, they tend to stay down, which is not always true of rifle-caliber fire or SMGs (which use pistol rounds).

All of this ignores body armor, true. However, not a lot of people use body armor. Soft armor with no plates will stop shot (but MAN you'll be bruised up, and you'll have a few holes in you from where you didn't have armor). Soft armor with plates will most likely stop slugs, assuming it hits a plate (which is depressingly small) and there's no penetrator component to the slug. You have a much higher chance of being knocked over when your body armor stops a round...look above for the math. Basically, you're stopping something in an inch or less which would normally take several inches to stop, which increases the energy impulse dramatically. It's not normally an issue, as in RL, very few OPFOR use body armor to the extent that the US does.

Joran
2007-07-13, 04:07 PM
You're comparing shotguns to bolt-action rifles. Nobody uses bolt-action rifles for room-clearing unless they're suicidal. It's a non-issue. EDIT: unless they're got the old rifle-launched grenades that only fire off a BA rifle. But that's about the only way I can think of where you'd use one in this scenario.

Correct, but in terms of d20 game mechanics, a bolt-action rifle is far superior to a pump-action rifle in everything. They both have the same rate of fire, they are both the same size, do the same damage. The rifle has far superior range and they both share the same -4 penalty when firing at an adjacent enemy. There is no reason to pick the shotgun.

In the real world, obviously, they have different uses, but they aren't modeled in the d20 universe. I was trying to illustrate why a shotgun in the real world might be better at a specific task (close-in combat and room clearing) compared to a bolt-action rifle, where as in the d20 universe, the rifle would have no discernible disadvantage.

tainsouvra
2007-07-13, 04:21 PM
As a total aside, as long as physics are being brought up, it's not acceleration (force) that knocks you off your feet in the first place. It's jerk that'll do it. :smallsmile:

Swordguy
2007-07-13, 04:35 PM
Correct, but in terms of d20 game mechanics, a bolt-action rifle is far superior to a pump-action rifle in everything. They both have the same rate of fire, they are both the same size, do the same damage. The rifle has far superior range and they both share the same -4 penalty when firing at an adjacent enemy. There is no reason to pick the shotgun.

In the real world, obviously, they have different uses, but they aren't modeled in the d20 universe. I was trying to illustrate why a shotgun in the real world might be better at a specific task (close-in combat and room clearing) compared to a bolt-action rifle, where as in the d20 universe, the rifle would have no discernible disadvantage.

I don't recall d20 modern mechanics offhand, but don't BA rifles take a move action to work the bolt? Pump-action shotguns would have the same disadvantage, but semi-auto ones wouldn't. Is there no differentiation between break-action, pump-action, semi-auto, and full-auto shotguns?

In addition, there SHOULD be differing mechanics for shot and slug rounds - so you get versatility from a shotgun, as opposed to the rifle. That's not even bringing all the "exotic" shotgun rounds into the equation (Dragon's Breath, flechette, beanbag, stun rods, gas, liquid, etc.).

I would feel safe in houseruling the "adjacent enemy" penalty for a shotgun away if it wasn't a long barreled shotgun (hunting guns). That, plus the versatility, ought to give people a reason to use them.

vrellum
2007-07-13, 09:40 PM
Arrrg. I suppose I mistook "force" for "energy." Impulse I'll give you for sure; it's the same reason that a boxer pulling his head away from a punch can cut the force in half or more by lengthening the time of the deceleration. And the same reason paintballs hurt so much more when they bounce then why they splatter.

I'd still be interested to see some real, practical data on this. I like me some physics, but all of those equations just make me dizzy.

Seriously, though. Has no one seen that episode of Mythbusters? I thought everyone loved that show...

Hey, you (or maybe it was someone else) said they wanted to see some physics :smallsmile:

I don't have any real data on the subject, but I have shot a few deer and I know several other people who have as well. From that I know that a rifle bullet (or a shotgun slug) will not lift a deer (person) off the ground, but it might knock them down.

Mythbusters is a cool show and it can be pretty entertaining, even informative. But I don't think their test is exactly measuring what we are talking about, unless we're talking about the impact knocking someone up into the air and back into a wall. In that case I think their test was fine and showed bullet impacts don't do that sort of thing.

Fawsto
2007-07-13, 11:09 PM
About illegality, in Brazil what would be called "SWAT" possess and uses full-auto shotguns... I've seen one in action, against a non-living target of course, but it was quite devastating, in a moment there was a target, after the rain of death, there wasn't.

That is in fact a problematic question, wouldn't a full auto SMG do far more damage in close combat than a non auto shotgun? Specialy with Hollow Point Ammo? Ok, the boomstick has a cloud of small deathdarts, but a single burst from a HK-MP5 SD can take a boar out without it even noticing. I guess it is hard to tell, the current analysis sounds far more correct than this one, but burst weapons in close quarters seem to do a abusive damage.

But there is in fact an important thing to remember: One round of a heavy shotgun, I guess the SPAS is a good example of one, can cut a limb off... That would be mostly anoying.

Hmmm... I guess that the Garand was the best non-shotgun weapon from WW2 armories. However it sucked in close ranges, where the Thompson and the Browning AR would excel, the last one for it Huge bullets.

blue chicken
2007-07-13, 11:21 PM
vrellum:

Oy. Never bite off more than you can chew. I was hoping for something pre-blended and digested for my tiny, infant brain.

As for Mythbusters...um...weren't we arguing that even a shotgun really doesn't throw the target much? I don't disagree with that, and I liked that episode because it proved that the actual bullet itself usually doesn't move the target too much.

I've never argued that someone wouldn't go down from taking a shotgun blast. I sure would.:smallwink:

Dhavaer
2007-07-13, 11:48 PM
I don't recall d20 modern mechanics offhand, but don't BA rifles take a move action to work the bolt?

No, the slowest fire rate barring crossbows is Single, which just means you can't double tap with it.

Fawsto
2007-07-14, 12:05 AM
Crossbows? Aren't we dealing with Bolt-Action rifles... Sorry if I am being ignorant... Pehaps I am not translating this well.

Dhavaer
2007-07-14, 12:28 AM
Crossbows? Aren't we dealing with Bolt-Action rifles... Sorry if I am being ignorant... Pehaps I am not translating this well.

I'm saying that the only things that fire as slowly as Swordguy describes are crossbows.

Fawsto
2007-07-14, 12:33 AM
Ohh yeah, now I see it, you are accurate on that. Bolt action rifles take no more than 2 seconds to place the new projectile, saying that you need a entire move action to place it is too much... It is mostly a simple action, almost as simple as pumping a shotgun.

Sorry for my ignorance. :smalltongue:

Irenaeus
2007-07-14, 01:08 AM
I don't have any real data on the subject, but I have shot a few deer and I know several other people who have as well. From that I know that a rifle bullet (or a shotgun slug) will not lift a deer (person) off the ground, but it might knock them down.

Like Blue Chicken, I'm a bit confused here. Do we agree that the deer falling down is an effect of the damage, not of the any knock from the weapon? Because if we do then this should be modelled as an effect from any kind of damage and should scale to the amount of damage.

If you suggest that the actual 'knock' of the projectile is the cause of the fall, then I don't quite understand how it would be able to do so.

A 12-gauge slug weighing one ounce, hitting a target at a speed of 1700 f/s, even if being fully and instantly stopped by a 150 lbs target, would only transfer about 0.71 f/s on to the target.

This calculation would be a quite powerful load being stopped impossibly fast, and it would still not knock a relatively small target down. A strong punch from a another 150 lbs person (say he is able to put half his weight behind his punch at 15 f/s) would transfer 7.5 f/s on to the target. That is more than ten times as much as the slug! If I am making a mistake here somewhere, please tell me. If not I have to conclude that any knockdown effect caused by the transfer of force alone is negligible.

Swordguy
2007-07-14, 02:33 AM
Like Blue Chicken, I'm a bit confused here. Do we agree that the deer falling down is an effect of the damage, not of the any knock from the weapon? Because if we do then this should be modelled as an effect from any kind of damage and should scale to the amount of damage.

If you suggest that the actual 'knock' of the projectile is the cause of the fall, then I don't quite understand how it would be able to do so.

A 12-gauge slug weighing one ounce, hitting a target at a speed of 1700 f/s, even if being fully and instantly stopped by a 150 lbs target, would only transfer about 0.71 f/s on to the target.

This calculation would be a quite powerful load being stopped impossibly fast, and it would still not knock a relatively small target down. A strong punch from a another 150 lbs person (say he is able to put half his weight behind his punch at 15 f/s) would transfer 7.5 f/s on to the target. That is more than ten times as much as the slug! If I am making a mistake here somewhere, please tell me. If not I have to conclude that any knockdown effect caused by the transfer of force alone is negligible.

Real-life aside - the Takedown quality of a weapon in Spycraft (which is the game Ive been pushing for this whole thread) is dependent on the Wound Damage dealt. Ergot, it's probably modeling the effects of nervous shock and reflexive action on the part of the target rather than transfer of inertia.

And I've NEVER seen an Iraqi not drop instantly when hit by a shotgun. They ran around after being hit with 5.56 fire all the time. Anecdotal? Sure. Make of it what you will.

Kioran
2007-07-14, 02:53 AM
Hmmm... I guess that the Garand was the best non-shotgun weapon from WW2 armories. However it sucked in close ranges, where the Thompson and the Browning AR would excel, the last one for it Huge bullets.

Incorrect. These honours go to the Sturmgewehr 44(the first assault rifles and the origin of the term) and the Fallschirmgewehr 42(a very good light Machine gun, never produced in significant numbers), with the russian Ppsh being the king of submachine guns(though a case can be made for the pre-war Thompson, which were made to a significantly higher standard than the mass produced weapons of the war).
The G43 also was quite good, as a semi-automatic 7.92mm Rifle, and thus much more powerful than a Garand. No surprise, since the Garand was developed as a self-defense weapon for vehicle crews initially, and served quite well in that capacity since it was shorter and more compact than most rifles.

Machine guns are, as hard as some may find that to believe, actually precision weapons. They have long barrels and tripods or other mounts mostly, so in short bursts, they can actually fired with a lot of precision, comparable to rifles. A Machinegunner spraying an area usually doesnīt do it for any other purpose than keeping their heads down, not necessesarily for hitting anything(and for that, the mechanics with the Reflex save do okay).
Shotguns? I agree they should do more damage, and that it should decrease with range. But they are actually useful weapons. That they donīt get any love in D20 modern is a bit sad.

Dervag
2007-07-14, 03:31 AM
with the russian Ppsh being the king of submachine guns(though a case can be made for the pre-war Thompson, which were made to a significantly higher standard than the mass produced weapons of the war).What traits would make the PPsh 'king' except for its great numbers?


The G43 also was quite good, as a semi-automatic 7.92mm Rifle, and thus much more powerful than a Garand. No surprise, since the Garand was developed as a self-defense weapon for vehicle crews initially, and served quite well in that capacity since it was shorter and more compact than most rifles.That was the M1 carbine, not the M1 rifle. The M1 carbine was a variant on the Garand design so different as to be an essentially different weapon; it had a folding stock like the Sten or Uzi and a magazine twice the size of the M1 rifle.

The Garand rifle was intended as an infantry weapon from day one.


Machine guns are, as hard as some may find that to believe, actually precision weapons. They have long barrels and tripods or other mounts mostly, so in short bursts, they can actually fired with a lot of precision, comparable to rifles. A Machinegunner spraying an area usually doesnīt do it for any other purpose than keeping their heads down, not necessesarily for hitting anything(and for that, the mechanics with the Reflex save do okay).I think that references to 'machine guns' on this thread are using 'machine gun' as a colloquial name for 'automatic weapon', and not referring specifically to heavier, bipod or tripod mounted automatic weapons.

Cyborg Pirate
2007-07-14, 05:34 AM
A question: I've no real personal experience with firearms (what with living in a place where they're illegal and all that), but I have been doing a lot of research on them for my projects and such.

A long while ago, I didn't much realise the difference in power between a rifle round and a pistol round. When it was made clear to me, I was surprised at the massive difference in power, in how a rifle round's ability to blast through protection and cause massive hydrostatic shock seemed to go up exponentially with caliber rather then linearly.

But now I'm a little confused. How do shotgun slug compare to the larger rifle rounds? I don't mean the tiny 'lets-hurt-the-enemy-rather-then-kill-em' 5.56, but say the 7.76 nato and up, how do they compare to a slug at say a 100 yards?

Kioran
2007-07-14, 07:16 AM
Shot is mostly subsonic, and even if there were some supersonic slugs or even shot, they are most likely around 1-1,2 Mach, while a 7.62mm NATO or 7.92 Infanteriepatrone spitz are around the 2,5 Mach range. Twice as fast means four times the energy.
But then, 12 gauge means throwing aroung a 12th of a pound of lead, which is a lot mor than 180 grains (most 7.62er, tranlsates to about 11 grams) or 220 grains (7.92er, evil and very powerful caliber. But then, so is 06-03 Springfield). That means your slug or shot is thrice as heavy. So on short ranges, you have a similiar impact energy, but "use" more of it. On long ranges - meh. You lose kinetic energy much faster. For anything beyond a 100 meters Iīll gladly take a rifle.

vrellum
2007-07-14, 08:26 AM
Like Blue Chicken, I'm a bit confused here. Do we agree that the deer falling down is an effect of the damage, not of the any knock from the weapon? Because if we do then this should be modelled as an effect from any kind of damage and should scale to the amount of damage.

If you suggest that the actual 'knock' of the projectile is the cause of the fall, then I don't quite understand how it would be able to do so.

A 12-gauge slug weighing one ounce, hitting a target at a speed of 1700 f/s, even if being fully and instantly stopped by a 150 lbs target, would only transfer about 0.71 f/s on to the target.

This calculation would be a quite powerful load being stopped impossibly fast, and it would still not knock a relatively small target down. A strong punch from a another 150 lbs person (say he is able to put half his weight behind his punch at 15 f/s) would transfer 7.5 f/s on to the target. That is more than ten times as much as the slug! If I am making a mistake here somewhere, please tell me. If not I have to conclude that any knockdown effect caused by the transfer of force alone is negligible.

I think a rifle or shotgun could knock someone down, though it won't necessarily do so and it won't knock them backwards a few feet.

I don't quite follow your math. I think a slug with a weight of 1 ounce (mass = .028 kg) traveling at 1700 f/s (515 m/s) has a momentum of 3.3 slug*feet/seconds (14 kg*m/s). That seems sufficient to knock you down at least some of the time, granted it is a powerful round.

I think the impact from getting hit with a bullet/slug/etc. would slightly greater than placing the gun against the body part that is hit and firing the gun. If you place a shotgun in the middle of your chest and fire it, the impact is atleast going to hurt (I'm not sure how bad, because I've never done it and I don't plan on trying it.). I think it could be enough to knock someone down, if they weren't expecting it through a combination of pain and force.

However, I do think the main reason things fall down when they are shot is because of the damage done by the bullet breaking bones/tearing up tissue and organs.

I don't know the knockdown mechanic in d20 modern, but it is probably not realistic in the least.

One last opinion, I think people often put too much emphasis on the kinetic energy of the round and not enough on the momentum. KE is important because the transfer of KE does most of the damage. However, the ability to penetrate deep enough that the damage matters is also important and that is more closely related to momentum.

Kioran
2007-07-14, 08:56 AM
I think a rifle or shotgun could knock someone down, though it won't necessarily do so and it won't knock them backwards a few feet.

I don't quite follow your math. I think a slug with a weight of 1 ounce (mass = .028 kg) traveling at 1700 f/s (515 m/s) has a momentum of 3.3 slug*feet/seconds (14 kg*m/s). That seems sufficient to knock you down at least some of the time, granted it is a powerful round.

I think the impact from getting hit with a bullet/slug/etc. would slightly greater than placing the gun against the body part that is hit and firing the gun. If you place a shotgun in the middle of your chest and fire it, the impact is atleast going to hurt (I'm not sure how bad, because I've never done it and I don't plan on trying it.). I think it could be enough to knock someone down, if they weren't expecting it through a combination of pain and force.

However, I do think the main reason things fall down when they are shot is because of the damage done by the bullet breaking bones/tearing up tissue and organs.

I don't know the knockdown mechanic in d20 modern, but it is probably not realistic in the least.

One last opinion, I think people often put too much emphasis on the kinetic energy of the round and not enough on the momentum. KE is important because the transfer of KE does most of the damage. However, the ability to penetrate deep enough that the damage matters is also important and that is more closely related to momentum.

Penetration is mostly a matter of energy per square centimeter and bullet cohesion(hence Tungsten Carbide for Europenas, who are a little more hesistant than the U.S. to sling around depleted Uranium - itīs heavy and relatively solid, making for good armor piercing rounds). But rest assured - a normal rifle(Full metal jacket) round, even a 5.56mm, will simply punch through most unarmed targets, dealing significantly less damage than shot.

vrellum
2007-07-14, 05:46 PM
Well, that is true.
I oversimplified my statement quite a lot and I was somewhat wrong because when I think "bullet" I rarely think "FMJ". My first thought is "copper jacketed lead", or the type of bullets used for hunting.

Kioran, you probably know all the stuff I'm about to say, but I'll say it anyway.

With a FMJ round, the bullet tends to retain its shape pretty well after impact and they penetrate very well, but they don't do a good job at killing their target, because, as you said they over-penetrate.

Hunting bullets on the other hand are designed to stay inside the target. They are designed to expand upon impact, create a large wound channel and usually do a lot more damage to the target than a FMJ round.

A lot of research has gone into designing these bullets, some are designed to penetrate deeply (big game, like those designed for large animals) and some are designed to practically explode on impact (varmit rounds).

Given the constraints that the bullet is made of lead, with a copper jacket, that it needs to penetrate deeply (for a large animal) and that it needs to expend all of its energy in the target (for maximum effect), bullet mass becomes more important than some give it credit for. Light lead, nonFMJ bullets will tend to fragment when penetrating a tough target, like a bear, losing kinetic energy and mass. They're also more likely to be deflected by a bone (though that can be a problem regardless of bullet mass). So under these conditions, heavy bullets (that will therefore have more momentum), of the same design as the lighter bullet, are better penetrators than lighter bullets.

Kioran
2007-07-14, 06:55 PM
Well, that is true.
I oversimplified my statement quite a lot and I was somewhat wrong because when I think "bullet" I rarely think "FMJ". My first thought is "copper jacketed lead", or the type of bullets used for hunting.

Kioran, you probably know all the stuff I'm about to say, but I'll say it anyway.

With a FMJ round, the bullet tends to retain its shape pretty well after impact and they penetrate very well, but they don't do a good job at killing their target, because, as you said they over-penetrate.

Hunting bullets on the other hand are designed to stay inside the target. They are designed to expand upon impact, create a large wound channel and usually do a lot more damage to the target than a FMJ round.

A lot of research has gone into designing these bullets, some are designed to penetrate deeply (big game, like those designed for large animals) and some are designed to practically explode on impact (varmit rounds).

Given the constraints that the bullet is made of lead, with a copper jacket, that it needs to penetrate deeply (for a large animal) and that it needs to expend all of its energy in the target (for maximum effect), bullet mass becomes more important than some give it credit for. Light lead, nonFMJ bullets will tend to fragment when penetrating a tough target, like a bear, losing kinetic energy and mass. They're also more likely to be deflected by a bone (though that can be a problem regardless of bullet mass). So under these conditions, heavy bullets (that will therefore have more momentum), of the same design as the lighter bullet, are better penetrators than lighter bullets.

Yeah okay - two different perspectives. My experiences with weapons were limited to 9 months of mandatory military service and some Firearms training, and military usually fires FMJs because they work better against armored targets or at long distances.
I do admit that you would be right in saying that most U.S. citizens would probably have soft- or half-jacket ammunition which either fragment (the M16 5.56mm was designed to do it, but only does so with sufficient velocity i.e. at less than 50m, one reason why some soldiers want more powerful calibers) or "mushroom" (deformation which increases the affected area and mass of the target, mostly to use more of the energy and to avoid overpenetration) inside the target.
So Yeah, that oneīs probably right. But the performance of different weapons varies largely in military/paramilitary vs. armed Civilian(i.e. Hunter or Self-defense weapons) comparison. Civilian Weapons are often more precise(no bull!), but more expensive and a lot less reliable and fire different ammunition.