Bullets: Overpenetration, Tumbling, Traveling

[Icelander]

Originally Posted by Tomsdad

.22LR really isn't good execution round through the skull.

In real life, it's plenty. The .22 LR is a pretty specific edge case where the DR 2 of the skull and the low damage of the round from a pistol can really produce anomalous rules artifacts in GURPS. This holds especially true for .22 LR designed for shooting people, as opposed to target or plinking rounds.

A .22 LR hollow-point from a pistol performs as a less-than-lethal munition when fired at a skull in GURPS rules. This is not true of reality, where .22 LR hollow-points may be stopped by the skull, but not so reliably that 66% of the time they simply force a HT check to avoid falling unconscious without any lasting trauma, ca 16.7% of the time they cause a wound that an average man will recover from in a week or so and on anything but a critical hit, the worst trauma possible is still not enough to kill even a tiny person with HP 5 (i.e. a child). Hell, it takes a critical hit that does triple maximum damage to have a chance to kill an average person. And that's something like on the order of one in every 5000 shots or so.

Under GURPS rules, shooting someone in the back of the head with a .22 LR hollow-point is a safer way to knock them out without lasting trauma than the beloved-of-movies knock-out punch.*

In my games, I refuse to allow the AD (0.5) of expanding rounds to affect the DR 2 from the human skull. A perfectly realistic treatment would recognise that expanding bullets do penetrate worse in flesh and are marginally more likely to fail to penetrate the human skull, but against that, the penetration of .22 LR and many other small bullets in flesh and other soft mediums is a lot better than its penetration of RHA plate.

*An average person punching with AoA (Strong) does 1d-1 cr. Aimed at the skull, this has only a 50% chance of knocking someone out without lasting trauma and the worst damage result that can occur without critical hits can actually put a normal person in a coma. On that HP 5 child that it's safe to shoot in the back of the head with the hollow-point, 16.7% of punches to the Skull will do enough damage to force a death check (and likely put the child in a coma even if it makes the death check).

[(E)]

For a real world example I use a .22LR to kill cattle, I haven't yet used more than one round to do it. Front on, hollow points, aiming for the fontanelle, using a rifle with iron sights, range from point blank to 20 or so meters. If the circumstances called for shooting the animal from any further away I would use a larger caliber probably a .22 magnum. I have shot maybe 20-30 cattle (cows and bulls).

[Tomsdad]

Originally Posted by Icelander

In real life, it's plenty.

You took half a sentence out of a much longer post that followed a post that pretty much showed how a .22LR to the head in GURPS can easily lead to death. It's just a surer thing with more powerful rounds, my point was in that context.

There's a reason why those chaps in the basement in Poland in 1940 were not using .22's

But I agree with your points about Skull DR and low powered hollow points interacting oddly.


I actually think really low DR probably shouldn't be doubled when it comes to hollow point as the such low DR probably won't meaningfully benefit from the less hard material, especially the min DR 1 bit! (human skin really shouldn't suddenly take on the DR effectiveness of hardened leather when resisting hollow points)

As you say it gets weird anyway with 1d+1 damage. 1d+1 pi- vs. an un-armoured target = on average a 2pt injury

Make it 1d+1 pi (AD0.5, min 1DR) and it's still = on average a 2pt injury

The closer you get to maximum damage the more it favours the hollow point though.

This leaves aside that some lower velocity round won't fully expand a hollow point anyway (this includes a lot of .22LRs fired from pistols)

But it is a round with a long history and a wide range of performance which is also something that doesn't help this conversation when trying to apply it to real world experience. Given a range of 575 to 1,750 ft/s (175 to 533 m/s). it very much matters what .22 you're firing and what you're firing it from!

And of course even if you don't penalise hollow points when going through the skull, you get no benefit in GURPS anyway as the location injury multiplier supersedes the adjusted round's multiplier.

[L.J.Steele]

Originally Posted by FF_Ninja

Well, I've got a decent grasp of the kind of damage rounds do when they penetrate. I've observed slow-mos of ballistic gel, read some articles, and even seen a few relevant examples in real life.

If you really want the nasty details of bullet damage, you want to read DiMaio's Gunshot Wounds. There's a new edition out. DiMaio was a leading medical examiner for Texas -- lots of information, including pictures, of exactly what happens when someone gets shot. Not for the squeamish or after a meal. Available from CRC Press, Amazon, possibly your local medical school's library which might let you in for research.

Bullets are random. I've had homicide cases where the victim got shot once with a .22 handgun round that just happened to hit the wrong spot and the victim bled out. I've had assault cases where the victim is the luckiest stiff on the planet -- hit mid-torso between 5-7 times with a medium caliber handgun round and was able to walk/run/drive away to medical help and survive.

[Icelander]

Originally Posted by (E)

For a real world example I use a .22LR to kill cattle, I haven't yet used more than one round to do it. Front on, hollow points, aiming for the fontanelle, using a rifle with iron sights, range from point blank to 20 or so meters. If the circumstances called for shooting the animal from any further away I would use a larger caliber probably a .22 magnum. I have shot maybe 20-30 cattle (cows and bulls).

Yeah, even with the ultra-rare critical hit result that does triple damage and a maximum damage roll, I don't think that can happen in GURPS. A bull with 25+ HP will never be killed with a .22 LR hollow-point under normal GURPS rules.

If you're using the harshest bleeding rules, a bovine might bleed out in an hour or two. But that will only really happen on a critical hit that does double or more damage or ignores DR.

I think that many bullets might have AD(2) on a lot of targets, pretty much anything that isn't hard enough to cause the bullets to fall to pieces. It's true that a .22 LR won't penetrate steel plate very well, but it will penetrate a lot more ballistic gelatin than GURPS rules suggest.

[Tomsdad]

On killing livestock with firearms, here's quite an interesting document regarding it,

now as its the Humane Slaughter Association it's setting the threshold at pretty much instant death of course!

in general this is what it says about .22 rim fire from rifles:

"The .22 inch rim-fire are usually used for vermin control (rats and rabbits) but can be used effectively, when loaded with the correct ammunition, to kill young cattle, horses, sheep, deer*, goats, and pigs up to 100kg, when shooting from a short distance (from 5-25cm away). However, they do have limitations in that there is no margin for error in respect of position and angle of incidence."


However earlier it does make the point that:


"For these reasons, the ideal ammunition is one which expands upon impact and dissipates its energy within the brain cavity. The ideal performance of an expanding bullet is achieved when the nose material peels back upon itself to form the classic ‘mushroom shape’ at the correct depth of penetration in the animal’s head. This expansion must be achieved without the bullet breaking up or suffering an unacceptable degree of weight loss. The expanded bullet should also utilise its potential for tissue destruction at the optimum point of penetration, to cause maximum destruction in the internal area containing the mid-brain and brain stem. "


Which does to me suggest that hollow point / bullets designed to expand do give a benefit here that you don't see in GURPS!

[Tomsdad]

Originally Posted by Polydamas

..
Executions are an excellent example of the kind of situation where its best not to roll damage, since the damage rules are designed for combat. A common house rule is to give executioners who can set up the situation correctly (and maybe make a skill roll) an automatic high-damage critical hit (see Low Tech, I think).

Just to say this is a good point!

[Tomsdad]

Originally Posted by Icelander

Yeah, even with the ultra-rare critical hit result that does triple damage and a maximum damage roll, I don't think that can happen in GURPS. A bull with 25+ HP will never be killed with a .22 LR hollow-point under normal GURPS rules.

If you're using the harshest bleeding rules, a bovine might bleed out in an hour or two. But that will only really happen on a critical hit that does double or more damage or ignores DR.

I think that many bullets might have AD(2) on a lot of targets, pretty much anything that isn't hard enough to cause the bullets to fall to pieces. It's true that a .22 LR won't penetrate steel plate very well, but it will penetrate a lot more ballistic gelatin than GURPS rules suggest.

Just quickly triple and maximum damage with .22LR from a rifle (1d+2) is 24 damage, even of you loose 4 to a skull with AD (0.5) that's 20 damage that a 80 injury which even on a 25 HP bull can kill instantly


However I take your point regarding the kind of extreme luck that result requires is not modelling expected reality!

[DouglasCole]

Originally Posted by L.J.Steele

If you really want the nasty details of bullet damage, you want to read DiMaio's Gunshot Wounds.

DiMaio, Fackler, MacPherson are the right places to start, definitely. They're not always consistent with each other, because disagreements exist even among experts, but these three are required reading.

[Eukie]

Originally Posted by DouglasCole

DiMaio, Fackler, MacPherson are the right places to start, definitely. They're not always consistent with each other, because disagreements exist even among experts, but these three are required reading.

I've gotten much use out of Kneubuehl's Wound Ballistics: Basics and Applications, which addresses Fackler, MacPherson, and other authors and also gives a thorough treatment of the underlying physics.