Firearm Muzzle Energy

[Tweedle]

Thanks gang for your intelligent analyses and suggestions.

[Rapier]

Absolutely, though if you brace too well and have a very powerful weapon that is meant to recoil you will shatter your shoulder. OUCH!

I went to Uni with a bloke that when he was younger stood with his back to a tree when firing a shotgun. Broke his collar bone and dislocated his shoulder. Still gives him problems to this day any time the weather changes.

<cheers for fellow physicists>

[Cpt.Storm]

I went to Uni with a bloke that when he was younger stood with his back to a tree when firing a shotgun. Broke his collar bone and dislocated his shoulder. Still gives him problems to this day any time the weather changes.

<cheers for fellow physicists>

As I said, OUCH!! But at least he has a good, built-in barometer.

[RDU Neil]

Much apparently also has to do with the targets reaction to being hit, you can throw a punch at a 150lb person and knock them to the ground but if you threw that same punch at a 150lb slab of beef it would barely move. The same goes for bullets, most of the "knockback" seen is the result of the body reacting to being hit, not the bullet knocking the target down (A bullet that weighs 1/2 ounce is pretty heavy, but it is still only 1/2880 the weight of a 90lb weakling).

True... it's all an issue of balance. If the body is shaken/stunned by the blow, the muscle control goes and can fall, topple, go over backwards, whatever. A slab of beef well balanced isn't going to move, but if it was somehow "balanced on edge" the blow could be enough to knock it over. Center of gravity and all that.

As for blow through I've been reading GURPS 4e and I rather like their new blow through rule, a person only stops 10 pts of damage, the rest continues on able to possibly hit something else. The target still takes full damage it just doesn't soak up all of the bullets energy, of course body armor needs to be considered as well and they point out the bullet must penetrate the armor on the backside while exiting just like it did entering.

I don't see why this wouldn't work just fine for HERO although you may need to adjust for the lower damage of HERO, maybe only 5 or 6 Body not 10, so most pistols would have some danger of over penetration while powerful pistols (.44 Mag etc) and rifles have a pretty fair chance.

To provide an example say we have Ned Notsobright, he is in the midst of robbing the Bigger is not good enough gun shop, when the owner gets the drop on him with his .800 Cthulhu Express (TM) letting loose with all 4 barrels (we will just deal with one bullet though for simplicity), Ned has 10 body and Class 2 body armor (worth say 5 pts of armor), the .800 CE does 4d6 rolling a 19, Ned takes 14 body (19 minus the 5 pts of armor), but the .800 CE is only slowed by 15 (5 for the front of the vest, 5 for Ned and 5 for the back of the vest) 4 pts continue on to damage an unfortunately placed 3rd dynasty Ming Vase.

Shouldn't be to complicated and adds some variety to the game (know whats behind your target).

I think DC also had some mention of this option but that might be my imagination.

This is basic "Hero system physics" modified. Any body of an attack left over after defenses and Body are applied to attack, that continues on. You seem to just be arbitrarily lowering the amount of target body.

It makes sense in a "just wing it" way. I certainly do that plenty in my games.

This discussion just indicates one of the areas where the Hero System breaks down. Damaging inanimate objects (as the blow through idea really is looking at the human body as simply an object, not a living, hurting, vital organ kind of being.) just really doesn't make sense in Hero.

Example: A brick wall might have 4 rDef and 8 Body.

So... how big is this brick wall? Let's say one hex... two meters wide, two meters tall.

Now... how thick is the wall? 4 inches say? Lets go with that.

Ok... so "8 body" does that mean, in the entire four square meters of 4 inch thick brick there is only "8 Body" worth of mass? Seems very low if Body is an abstract measure of mass (brick mass, tissue mass, earth mass, whatever).

Now... a .45 will strike only .45 inches worth of this four square meter, four inch thick object. In that small piece, less than half and inch, is there ALL 8 BODY in that small piece? If so, then divide four meters into all the .5 inch pieces multiple x8 body... that is a HUGE amount of body. Doesn't make sense.

So... what do we do with this?

How much "Body" represents the "total mass" of an object? Wall, human body, tree stump, etc. Is there any game measurement for this? Should the stat of Body even be related to the concept of "mass" or is it a totally abstract number that has only vague representation in real world terms?

So... in your example, while it makes sense the bullet needs to penetrate 5 armor twice (going in, going out) but... exactly how much of the targets "mass" ... it's Body... does the bullet actually strike? If I have 10 Body... how much of that is in my head... my neck... my forearm... my big toe?

These kind of questions just aren't easily addressed by the simple Body/Stun damage system... and this is evident with the Blow Through concept. The bullet shouldn't have to penetrate all 10 of my body to Blow through... but just how much SHOULD it penetrate?

Interesting questions... I'm definitely interested in any ideas how to make this work in the game.

[Captain Obvious]

I would say, using the Object BODY Table on FREd p. 304, that the point at which damage blows through a human should be 7. The table is constructed under the assumption that complex machinery is easier to break than typical lumps of unliving material, and that living creatures have a will to survive that allows them to persevere better than said typical lump. Therefore, for a typical (for HERO) 100kg human, there is 7 BODY associated with size, and the other 3 is "will to live".

As for blowing through walls, I would say that the bullet would have to overcome the DEF and BODY of the wall, and whatever was left would blow through. Since this is a Beam weapon and not a blast type RKA, the hole would be about the same size as the bullet on the entry side, and somewhat bigger on the exit side, depending on the material used in the wall.

Of course, this only applies to bullets. A grenade, for example, would be unlikely to blow through a human, even if it riddles his body with shrapnel. On the other hand, if a grenade blows through a wall, it will open a decent sized hole in most cases.

[gewing]

for those who are gun geeks, I read something interesting last weekend.

The penetration in Gelatin of a 12 gauge OO buckshot load is in the area of 15 inches, and OOO is about 18.

Much more than I would have expected.

[Toadmaster]

Back to blow through...

IIRC (and if I were not feeling particularly lazy I'd just get up and look it up) an inanimate objects body for something like a wall is to blow a 1m hole in it. Seems reasonable to me that a weapon with the "beam" lim could just apply the walls DEF and ignore the body, just assume it doesn't really do any body to the wall so it isn't slowed by the walls body either (or say 1 Body so you can eventually shoot a hole in the wall).


As far as living objects the change for GURPS was using a fixed number instead of maxing at 1x HT, the idea I guess is that all people stop about the same amount of damage and the rest is mental (so a 10HT and a 15HT stop a bullet the same but the 15HT has more "will to live"). Seems reasonable for HERO as well, of course it should probably be based off the "average" or base body since a human and an elephant will not provide the same amount of cover. I really should go back and check DC since we may be trying to reinvent the wheel, I recall something about this being in there.

[Toadmaster]

for those who are gun geeks, I read something interesting last weekend.

The penetration in Gelatin of a 12 gauge OO buckshot load is in the area of 15 inches, and OOO is about 18.

Much more than I would have expected.

I remember reading something similar several years ago, because of this some recommend using #4 buck or smaller shot, and some even suggest large bird shot for use in the home for defense.

If you compare ballistics 00 buck is similar to getting shot with a whole magazine from a .32ACP and 000 a .380 ACP.

[Cpt.Storm]

I remember reading something similar several years ago, because of this some recommend using #4 buck or smaller shot, and some even suggest large bird shot for use in the home for defense.

If you compare ballistics 00 buck is similar to getting shot with a whole magazine from a .32ACP and 000 a .380 ACP.

Any way you slice it, it's gonna be messy at short range.

[gewing]

I bought # 1 buckshot. it was cheap, and I figured at less than 30 feet...

more pellets to hit more vital organs.

There are slugs right next to them if more penetration is needed.

I remember reading something similar several years ago, because of this some recommend using #4 buck or smaller shot, and some even suggest large bird shot for use in the home for defense.

If you compare ballistics 00 buck is similar to getting shot with a whole magazine from a .32ACP and 000 a .380 ACP.

[Kevin Rose]

Because it is a readily available measuring method to compare differant bullets and it is not convieniant for most people to go out and conduct live fire trials on living subjects. Since there is no real reliable way to measure bullet effectiveness its as good as any other. I think you know the bowling ball, 2x4 analogies are bogus anyway, like most things its how you use it.

If you want to stick to useless but easily measured values that it certainly your option. I'd suggest that gun weight is even easier to find and measure, and has about the same correlation to effectiveness.

Killing the opponent is not the typical objective of bullet buyers, it’s stopping the opponent from doing whatever made you shoot at him. The opponent dying from a bullet wound two weeks after he beat you to death with his bare hands isn’t the ideal outcome. So what I’m saying is based on the idea that you want to stop this guy right now from doing something bad.

Muzzle energy is predominantly determined by velocity. The most significant velocity effect on a human is a larger temporary wound cavity. Temporary wound cavities are not correlated with any combat significant effect unless the cavity:

1) is huge compared to the target size (for example, very high velocity varmint bullets blowing up small critters),
2) strikes a confined area like the head.

If they disrupt the kidneys, liver, spleen, pancreas - the few organs that are susceptible to this - it may well kill the target, but it's likely to take hours or days. And this isn’t too useful when he's shooting at you now.

In particular, pistol class bullets do not produce significant effects from temporary cavities. Rifles can, but you need impact velocities at over several thousand FPS with a good sized bullet to get the tearing and shredding effect that do useful things.

Until you reach cannon round size and velocities, a through and through peripheral hit on a determined opponent won't do anything useful. If a bullet hits "the good stuff" the caliber is pretty unimportant. A CNS hit with a .22 or a .458 will both drop the guy right now. The likelihood of striking major blood vessels is really pretty much the same between a 9mm bullet and a 17mm bullet per MacPherson. Arteries are can be blown out by a small bullet or a large bullet, they are not that tough. If you strike a major blood vessel the guy should drop in short order. (Except when he doesn't, like Michael Platt didn’t that day in Miami.) These effects are determined by bullet placement, not caliber.

If you assume that the bullet doesn't hit anything particularly exciting it appears that the predominate incapacitation mechanism is the permanent wound cavity. Essentially, how big a hole does the bullet drill into the target and hence how much tissue is destroyed by the bullet. Velocity doesn't really matter except that the bullet has to be able to penetrate any barriers and still penetrate deep into the target. Wide, shallow wounds are not very effective in forcing someone to stop attacking. Bullets that sail right thought the target don't add anything.

What you are doing, as a shooting instructor once said, is “depressurizing their circulatory system�. You put enough bullets in them the blood loss and shock, broken bones and other bad things that this causes will eventually cause them to go down.

So, fundamentally, it's the actual bullet diameter inside the target and how much tissue it crushes that determines how effective the bullet is. Not the velocity or the energy. But bullet placement is even more important.

[Toadmaster]

Well first of all, since you disapprove of muzzle energy so much can you suggest another readily available measurement applicable to use in a game. So far you have dismissed an industry standard measurement and one of the most well known studies of actual shootings. Whats left?

You mention the relationship of velocity to penetration, damage in HERO most closely relates to penetration followed by effect on living tissue. This is one reason I relate muzzle energy to damage. I find Stun mod relates to putting the target down or "knock down" better, for stun mod I place far more importance on caliber and bullet weight, velocity plays a much smaller role primarily becoming important in weapons with lighter bullets at high speed (rifles mostly).

So my method uses muzzle energy for damage, bullet weight, caliber and a minor part for velocity for StunX. This works well to get low penetration high stun weapons like the .455 Webley (1d6 +2 StunX) and moderate penetration low stun weapons like the 9mm (1d6+1 +0 Stun).

Again as I've mentioned a few times I'm using this for a game, if I were picking a weapon for actual defensive use I consider much more than energy.


I don't mean to be argumentive but I'd be interested in an alternative vs ME is worthless.

I think we had a similar debate over on the old boards which I actually found quite interesting even if we didn't see eye to eye. Although I've pretty well set for my system of determinig HERO gun effectiveness it never hurts to hear other ideas.

I've copied my system from another post to give you some idea of what I'm using, comments are welcome.


Damage = ME (joules) base 100J> = 1DC, each doubling adds a DC (200 J = DC2, 400J = DC 3 etc) this works out very close to the original Hero stats.

StunMod = bullet weight (grams) x caliber (mm) + (Vel(m)/20)

99> = +0 stnmod
100-199 = +1 stnmod
200-399 = 2 stnmod

etc

From my reading it seems two things determine a bullets stopping power, high velocity and a big heavy bullet, in pistols most of the "man-stoppers" are big bores but the velocity portion allows medium bore high velocity cartridges like the .357 Magnum to get that +1. Similarly lighter bullets at high velocity in rifles (such as the 7.62mm NATO) also get that +1.


I also add piercing and rmod based on the cartridge in addition to rmod based on the gun. Velocity is important to armor penetration (I based this fact on formulas for figuring cannon armor penetration). Since the damage combines tissue damage and penetration piercing gives a little bonus to high velocity rounds without adding to the lethality of it. This is handy for rounds like the 5.7mm FN which have good penetration but questionable effect on tissue (small hole in and out).

Piercing
velocity
0-299 m/s = +0
300-599 m/s = +1
600-1199 m/s = +2
1200-2499 m/s = +3

etc

Rmod
velocity
0-249 m/s = -1 Rmod
250-499 m/s = +0 Rmod
500-1000 m/s = +1 Rmod
1000-2000 m/s = +2 Rmod

Again velocity is important, the faster a bullet the flatter the trajectory, so a fast bullet is easier to aim.


The overall formulas tend to favor velocity over bullet weight but because the stun mod is so heavily weighted towards big bullets I think it balances out. The .45 is still one of the best "man stoppers" in the service handgun catagory but it does not totally overshadow the 9mm Parabellum (the .45 is better but you can get more 9mm cartridges into a magazine which tends to be the real argument as well). The problem I found with many formulas I tried is they tended to seriously either favor heavy bullets or fast bullets, I think this one is balanced. I generally look at 9mm vs .45 and 5.56mm vs 7.62mm when playing around with damage formulas, there are valid arguments on each side and all have seen extensive real world use, if they all still have a reason to exist but also still have advantages over each other then I feel like I have a workable system.

[mudpyr8]

I've found that assessing "accurate" damage correlation between DC and any amount of gun statistics is difficult at best. GURPS does a pretty good job of representing this on many levels, but also presents a fairly lethal system for handling it.

This is what I've found works for me. Most weapons can be classified in this manner such that for a cinematic game it provides enough realism yet is easy to manage.

Pistol Rounds
tiny (5-6mm, .22) 1/2d6
v small (7-8mm,) 1d6-1
small (9mm, .38) 1d6
medium (.41, 10mm) 1d6+1
large (.45, 11mm) 1 1/2d6, +1 STUN
v large (.44 mag, .50, 12mm) 2d6, +1 STUN

high velocity (e.g. 9mm para, 357 mag) +1 DC

Rifle Rounds
All rounds are AP due to velocity
v small (3.5-5mm) 1 1/2d6
small (4.5-6.5mm, .223) 2d6
medium (6.5-8.5mm, .308, 30-06) 2d6+1, +1 STUN
large (8.5mm-10.5mm, .44, .45) 2 1/2d6, +1 STUN
v large (10.5-12.5mm, .50) 3d6, +1 STUN
huge (14.5mm) 3d6+1, +1 STUN

All "bullet proof" armor (Threat III & IV) provide one level of hardening. This means that a second chance vest (rPD 6 or 7) vs. a Rifle is still going to allow someone to die. However, a level II vest (DEF 8) is still going to offer good protection, since it's hardened, and if it has the inserts (+3 DEF) be effectively bullet proof vs. most rifle rounds.

This has worked really well for me. If you are using DC, just add AP to all rifles and hardened to level III/IV armor. Done.

[Kevin Rose]

I'll believe Dr. Martin L. Fackler, Colonel, U.S.A, one of the foremost experts in wound ballistics research, over a couple of guys who collect squirrelly data to write books touting the bullets that their friends’ companies sell. See the Letterman Army Institute of Research's Institute Report No. 239 from 1987 "WHAT'S WRONG WITH THE WOUND BALLISTICS LITERATURE, AND WHY" http://www.rkba.org/research/fackler/wrong.html.

Essentially all pistol bullets suck. They just do not do enough damage to reliably drop someone unless you get a central nervous system hit. Even when they do incapacitate someone, they are not nearly as fast as typically shown in the media. Hero has issues with how it does damage because of the superhoro basis. My personal approach is that bullets that tend to kill people reliably should do enough damage to do so, so .50 BMG at 4D6 or more seems reasonable. You could probably model all pistols as D3 (or worse) for everything from .32s to .45s and be roughly accurate. Single hits don't typically stop attacks in any caliber unless you get a central nervous system hit or convince the guy that he doesn't want to fight to to the death.

For example, I was reading through the most recent FBI Law Enforcement Officers Killed report on the FBI site. One guy got shot 12 times and recovered to stand trial. Last night a judge nearby got in shootout in his yard with a nutcase. Shot the guy 3 times in the stomach and twice in the chest with his 6 shot revolver, then ran into the house. The nut emptied his revolver at the judge and then reloaded before collapsing and dying. An ex-nypd detective talked about shooting a thug 11 times with a 9mm (during which the thug shot the detectives partner) before he collapsed, then getting indicted for it by the DA who'd watched too much TV. These are all people not wearing armor.


Hit location is probably the most important element. If can get a bullet into the "brain-housing group" the fight is over. You sever the guys spine, the fight is over. You bruise the spinal cord and the fights over (he might be fine a few hours later, or not, but the fight is over.) This is the drop like a puppet with the strings cut effect. Typically anyhow, as I have been told of a guy who got half his brain removed by a police sniper with a .308 and still shot two cops before he went down.

Motivation, aggressiveness and willingness to drive on is next. People have been killed by totally survivable wounds because they decided they were going to die, others have continued on after getting horrible wounds. I've heard of VC sappers continuing to fight after taking a burst of M-60 that blew an arm off. Lots of bad guys decide when the fight goes to guns that they are not going there. An ICE inspector mentioned that every time he has made an aggressive presentation on a bad guy that the bad guy decided that he didn't want to play that game. Even more decide that when they get hit that they really don't want to get killed and surrender. Some fight to the bitter end and keep operating effectively with fatal wounds. Platt took a fatal wound in the first few seconds of his shootout and still went on for 4 minutes shooting 5 FBI agents, collecting 11 wounds before he got shot in the spine and died. In Hero, EGO should be far more important that it is typically shown.

After that, it's more hit location. Hitting major blood vessels or the heart will take someone down fast. But it's not instant; it takes several seconds to knock you unconscious if you don't choose to drop out of the fight. More than one cop has drawn and shot a dirtbag dead after being fatally shot through the heart by surprise. As Michael Platt demonstrated in the 4 minutes after getting a hit from Dove that severed his brachial arteries and veins and damaged the main blood vessels of and collapsed his left lung, some people are hard to stop. Again, it’s EGO.

Past this the effects seems to be cumulative damage. Large holes in a person do more damage than little holes. Whether you drill them with a pistol or an electric drill, 7/8th inch holes placed essentially at random through someone’s torso have a better chance of hitting something important than 1/4 inch holes. Enough holes will stop anyone. Eventually. (People have killed attacking grizzlies with .40s and 9s, though it takes a lot of holes and isn't typically recommended.) I have seen autopsy pictures of a guy who took over thirty FMJ 9mm rounds, it looks in the poor B&W picture like he had a case of big measles.

This is where bullet type becomes critical. Good modern 9mms expand well, like .40s and .45s, but not as effectively. Federal LE Wounds Ballistic Workshop notes at http://le.atk.com/Interior.asp?secti.../downloads.asp show that top quality .45 and .40 get about the same expansion (.9 inch), with the heavy 9mm round penetrating significantly better than the light, fast 9mm while both expanding to .6 inch.

Stable FMJ bullets do far less damage than the same round that expands. Real body armor is really hard to model in hero without either hacking up the system a lot or going to complex disads like points of piercing, reduced penetration, etc.

Anyway, it’s getting really late. If you haven’t looked at a bunch of bullet tracks, you should do so. It’s pretty obvious what is more effective and why. Look at the Emergency War Surgery Manual’s selection http://www.vnh.org/EWSurg/ch02/02Projectiles.html

To see just how much bullet type matters when you get serious velocity see
7.62mm FMJ http://www.vnh.org/EWSurg/Figures/Fig07.html
7.62mm soft point http://www.vnh.org/EWSurg/Figures/Fig11.html
5.56mm FMJ http://www.vnh.org/EWSurg/Figures/Fig12.html
Compare these to the pistol profiles.

There are a few extra cross-sections here, at the bottom of the page: http://www.firearmstactical.com/wound.htm I’ve seen some more, like the 5.7mm one, but it doesn’t seem to be easy to find on the web.

[mudpyr8]

I agree with most of your points. What I'm saying is that HERO is not necessarily the game for this type of realistic model. HERO is about cinematic action, including where people take knockback from pistol rounds.

Having played Time Lords (BTRC - Guns, Guns, Guns), Phoenix Command, GURPS, and others, I can honestly say that GURPS does the best job of balancing realistic gunplay with playability. It accurately models the fact that 9mm have slightly better penetration than .45 but that a .45 does more damage, without introducing an Armor Piercing effect (i.e. so you can have AP rounds for both calibers).

It's fun, it's neat... but it's not cinematic.

Now, I generally don't go for things like KB for guns, but I think HERO does a pretty good job of providing an impression of reality while balancing heroic action and playability. Using the damage mod I suggested above (basically use DC with rifles doing AP and heavy armor having Hardened) you end up with something that approximates reality, provides granularity, and still feels like gunplay.

HERO provides a smooth exponential progression of effective power that is a pretty good mirror of nature (at times). When it doesn't match up perfectly, I feel it still matches up symbolically, and does what it was meant to do.