Why does penetration matter?

[toppermost]

I just had an epiphany, I guess.

Why are people so obsessed with penetration of hollow points?

"Power": To me the biggest attraction of a hollow point is the reduced chanced of over-penetration, i.e. shoot through. If your hollow points penetrate more and more wouldn't there be a higher chance of exiting your target and damaging whatever is behind it?

Don't get me wrong, I get the wound-size argument but... If wound diameter is your biggest concern I would think that higher penetration equals less time for expansion. So wouldn't rounds that penetrate less tend to expand more? I carry .40 S&W, it would seem to me that even if a JHP only enters 5 or 6 inches, it will cause a LOT of pain, damage, or worse -- and, of course, when a JHP "fails" it will essentially act like a heavy grain ball... while I have not read everything out there, I have never heard anyone complain about heavy ball ammo not "neutralizing" things.

[buck460XVR]

Why are people so obsessed with penetration of hollow points?

....because they spend too much time on gun forums.

Folks get concerned about penetration in SD/HD ammo because they want the bullet to get to the vitals. They are concerned that the bullet may have to go thru several layer of heavy clothing first or enter the torso from an angle where 5-6 inches of penetration will leave the bullet short of the boiler room. Then there are those that feel if one is accurate, bullet type will matter little. Good valid points...but so is the argument of over penetration.

This is why folks should use ammo for SD/HD that they are confident with because of personnel research and experience at the range with it. They need to consider the scenarios for which they may have to use the ammo and the type of threat that they may encounter.(i.e. weather dictating type of clothing, closeness of neighbors or others in the house and whether the BG is the average street punk or a drug hyped zombie)

[g.willikers]

Penetration must be enough to hit vitals.
Not enough and that grizzly or madman with the ax is still coming at you.
The risk of over penetration being a danger to anyone behind the intended target might be overblown.
If the statistics for self defense shootings are accurate, the vast majority of shots fired miss their intended anyway.

[Cheapshooter]

Because there is no such thing as "knock down power". The only absolute sure way to cause an attacker to be instantly incapacitated is destruction of the central nervous system. Brain, and spinal cord. A large bleeding hole may stop an attacker, but it may take long enough for them to still do harm to their intended victim.
Just being shot could stop an attack. Destroying the central nervous system will stop an attack.

[P71pilot]

It depends what the gun is for. I can only afford one quality handgun so I picked the gun that had the most all around uses and utility. I may some day need this handgun to bag deer for me, I may someday need this handgun to defend my from a person or dangerous animal. I need the pistol to be reliable, accurate and powerful. I made my choice and am happy with it. Penetration IS important to me. The more the better. Luckily I can choose different loads for different purposes. 200gr xtp HP for people, 230gr ball for targets and 255gr hardcasts for danger of the 4 legged kind

[spacemanspiff]

Living in a state where more than half the year most people wear thick layers of clothing to keep warm, I have always opted for hardball ammo. I've had an ample supply of jhp's though over the years, thanks to a friend who reloads, and before the ammo scarcity provided me with about 1500 rds of a variety of his favorite loads in 45acp. I still have about a hundred or so of those rounds left.

[tahunua001]

let's see the whole topic is a jumble in my brain so here we go. bullet points so I'm not a complete rambling idiot.
1. energy is calculated in foot pounds. a 9mm has a smaller cross section than 45 so theoretically a 9mm 147gr and an uber light 45ACP 147gr both traveling the same speed would both have the same FTLB but the 9mm would make better use of the energy because of it's smaller cross section as it's energy is more concentrated this factors into penetration.

2. you can have 1000FTLBs of energy but if your cross section happens to be mike tyson's fist, you're not going to have a lot of penetration but the sheer energy is spread over such a wide area that the tissue damage would still likely kill the person on the spot. in that case bigger is better because it's more spread out and likely to stop the opinion better.

3. since there are no bullets that are actually the size of mike tysons fist that can fit in your nightstand, we need penetration to make sure that concentrated energy actually reaches the internal organs in order to deliver the most shock to vital systems. I do not agree with the 16 inches necessary BS that the FBI recommends. unless you're shooting up from the floor vertically through the entire torso or you're taking on a body builder, you would never in a million years need 16 inches of penetration, the human heart lies meer inches from the rib cage in any direction, 6 inches would be lethal, and have little chance of overpenetrating but what do I know? I'm just some guy from the internet.

[45_auto]

Lots of confusion in the above post. Energy has no effect on tissue damage or stopping power. The AA batteries in your TV remote contain over 7,000 ft-lb of energy each. I hold all that energy in my hand pretty much every evening, no effects from it at all so far.

My 35,000,000 grain (5,000 pound) Chevy Suburban rolling down the driveway at 3 MPH has over 1,600 ft-lb of energy.

Stand in front of it and let those 1,600 ft-lb hit you, all that will happen is that you will get pushed along in front of it.

[Dragline45]

It's simple, you need sufficient penetration to hit vitals. If you don't hit those vitals all you are doing is poking holes in them. It's not like the movies where someone gets shot once or twice and falls to the ground dead.

To me the biggest attraction of a hollow point is the reduced chanced of over-penetration

Even if a handgun round did over penetrate, it likely has lost so much momentum once it comes out the other side that it is not nearly as lethal as when it left the barrel.

[TailGator]

I know I am just re-wording what has already been written, but maybe it will help:

A wound is three-dimensional, so the maximum damage is inflicted by a combination of expansion and penetration. A through-and-through wound with a narrow channel is what bullet designers are trying to avoid with handguns, simply because it has a lower chance of stopping a threat than a wider channel that stops inside the target. But you still want that three-dimensional wound to be deep enough to damage something that a bad guy needs to keep going.

[Mike Irwin]

"Why are people so obsessed with penetration of hollow points?"

Because it lets the evil cannibal bullet elves get deeper into the bad guy's body so they can eat him from the inside out.

[Derbel McDillet]

See pages 11-12 of "Handgun Wound Factors and Effectiveness" - http://www.firearmstactical.com/pdf/fbi-hwfe.pdf

[44 AMP]

The risk of over penetration being a danger to anyone behind the intended target might be overblown.

I don't think there is any "might be" about it. I think it is drastically overblown, when you are talking about civilian defensive shootings. I'm NOT saying it is of no concern, what I'm saying is that I think people are placing too much emphasis on avoiding complete penetration when considering defensive ammo.

If you are a large metro police dept, where you might have dozens (or more) shootings a year, in ALL parts of public places, then consideration of overpenetration is a serious matter. If you are the average fellow, who (hopefully) will only face such a situation once in their life (if that), I think you can put too much emphasis on worrying about "overpenetration".

Penetration matters, more than anything else, save proper aim. It matters MORE than any hollowpoint expansion. IF the bullet doesn't reach vital tissue, NOTHING else matters.

For one example, look at the 1986 Miami shootout. (and don't blow it off because it was ages ago and the ammo was "old tech", the principles involved are still valid)

The 9mm Silvertip that "failed" met all the penetration requirements of the day, in testing, and (I believe) that it also delivered that in the field that day, BUT, it wasn't quite enough. After going through the arm, the bullet stopped just an inch (or less) from delivering an incapacitating wound. It did deliver a FATAL wound, but not one that was immediately incapacitating.

In that precise situation, a FMJ bullet (or other non expanding type) might have gone enough further to sever vital tissue that silvertip failed to reach. (it might not have, also, but the odds are favorable that it would have).

Today, the "standards" have been revised, and the amount of "necessary" penetration required has been increased.

Expand or not, the bullet has to get there in order to work. And a load that will get there through layers of heavy winter clothes, and an arm and reach the vitals of a 260lb linebacker size guy at an angle will stand a real good chance of getting all the way through a 140lb guy in a t-shirt facing you directly.

Not being a police officer with the safety of the general public overall my primary concern, my standards are something that should reach the vitals of the attacker under the worst possible conditions I can envision. I want that, over something that is less likely to "overpenetrate", because my primary concern is stopping the attack, and the (remote) possibility of risk to others behind my attacker is of less concern to me than stopping the attack.

Non expanding bullets are statistically less effective than expanding bullets, but that does NOT mean they are not effective. ANY bullet that gets where it needs to go works, but to get there, you need penetration. And while many seem to worry about having too much, I'm more concerned about not having enough when I really, really need it.

[JD0x0]

People get way too hung up on the 'energy dump'
If energy killed, then you might as well work on your right hook, because most humans are capable of punching with more force than most common pistol cartridges.


-With pistol bullets you're making holes.

-Expanding bullets make bigger holes, at the cost of penetration.

-Solid bullets penetrate more, at the cost of having a smaller hole.

-If your hole isn't deep enough, it wont reach the intended vitals that must be damaged to cause a quick stop to a threat.


The case is completely different with rifle bullets which have considerably higher impact velocities and have much more potential to cause remote wounding effects. Some manufactures try to achieve these same effects with very light for caliber pistol bullets, but end up being so light that penetration is poor, especially if they expand/fragment, and the amount of impact energy tends to be anemic still, compared to a rifle cartridge.

IMO pistols are about placement and penetration. So, choosing an expanding bullet that reaches deep enough is important.

Personally, I would prefer exit wounds. IMO, the best potential results for a pistol cartridge would be full expansion, and full penetration, with enough energy expended in the target, that the exited bullet could be stopped by a piece of paper. Obviously, in the real world you can't guarantee those results in every situation, so I'd lean on the side of slightly more penetration over slightly more expansion/energy 'dump' for the highest potential of nice big, discouraging exit wounds.

[SSGN_Doc]

All pistol rounds suck for rapid incapacitation. (Except maybe in the magnum class).

If we want to talk "energy" and "shock", they are truly lacking when compared to true rifle cartridge chamberings or large bore shotguns.

The marginal performance of a handgun round depends on the bullet physically damaging tissue, opening blood vessels, or reaching vital parts of the central nervous system. Gun fights are dynamic, and chances of a shot being made straight on into an attackers chest with no obstruction from clothing, bone, cover, or other objects is not a high enough probability to bet on. Also, you don't get to pick how thick your attacker may be. So bullets must reach vital blood-filled organs, nerve centers, or major arteries to have the best chance of stopping an attacker in a relatively short time. Ask how long you want to continue receiving fire, taking standings, or getting beat with a bat.
If the bullet goes all the way through it is just fewer seconds for the blood to leave the body, and as others already pointed out most pistol bullets will have spent the majority of their energy before they exit.

[SIGSHR]

In years gone by people generally wore more clothes and plenty of men wore corsets. Also if you are a disciple of Jeff Cooper you will maintain that hollowpoints may fail but mass is constant. Also I think we're too hung up on the "one shot/zapped by lightning" notion, as well as watching too many movies and TV program where people absorb vast amounts of lead and we read all the similar "true life" stroies on the Web. I recall seeing a TV program showing surveillance tapes of an attempted robbery of a store, clearly recall seeing the perps shot by the store owner, running outside-and collapsing in the sidewalk, and ending up on a slab.

[Boogershooter]

It is cheap and easy to do yur own tests if u have a place to do it! It's also alot of fun! I've been using the same sand pile for over 20 years! Some real world tests I've done were on old coats/jackets! Vehicle glass! Milk jugs filled with water! Every type of material a wall n yur home can b made of! Phone books, lots of card board boxes! And many more just to satisfy my curiosity! All are easily attainable if u will ask around! Shoot yur favorite gun with two or three styles of bullets thru whatever u think would more closely represent your situation! If the bullets pass thru the sand will stop the bullet without much deformation! It will amaze you at what will and what won't stop a bullet!

[JohnKSa]

Energy has no effect on tissue damage...

Let's say we have two identical 100 grain bullets, one with a kinetic energy of 1ftlb and another with a kinetic energy of 1000ftlbs. For your statement to be true, we would have to believe that the tissue damage at impact would be the same since energy has no effect on tissue damage.

I don't think it's really even necessary to explain why the bullet that's going about 65fps will not do much damage while the one moving around 2125fps is going to wreck a good bit of tissue.

It's one thing to try to make a case for the idea that energy is over-rated as a measure of terminal performance. It's just plain ridiculous to try to claim that the two are absolutely independent of each other.

[Noreaster]

Optimal penetration depth use to be considered 6-8 inches but then incidents like the Miami FBI shootout occurred and the standard was raised to 12 inches. People are heavier then ever before, if someone is shooting at you they will probably have their arm(s) up in front of vitals and you have to penetrate through a forearm on the way to the chest, it may be an angled shot and require further penetration... In regards to over penetration, it's a concern but you're likely to have misses in stressful/dynamic shooting. A 100 pound opiate junky will get pass through by a .25 auto or you could be attacked by a buffed gym rat that just got out of prison. You will always have to be concerned with your target and what is beyond it.

[Mobuck]

I prefer a large, gaping wound to a small puncture wound, therefor, I use JHP ammo. My need is to "stop the attack by disabling/killing" and I feel HP bullets that expand readily are more likely to achieve that goal than FMJ/solid bullets which may "kill but not disable"(within the time constraints of the attack).
Much of the argument hinges on the idea that ALL hits will be in a critical area of the attacker's body. This is a BS idea-IT JUST DOESN'T HAPPEN THAT WAY. Peripheral hits to extremities(arms, legs) by expanding bullets are far more likely to disable or cause an aggressor to retreat than might bullets that punch neat little holes.
For those who think they're going to be able to hit exactly where they want during a confrontation, well keep that thought because you're one of very few who actually can.

[Snyper]

I would think that higher penetration equals less time for expansion

That makes no sense at all

Any expansion takes place in milliseconds, and the same applies to penetration

The higher the velocity, the more likely there will be expansion AND deep penetration, as long as the projectile doesn't come apart

You can't push a bellet so fast it won't "have time" to expand.

That's not how the physics works

[TimSr]

Personally, I don't penetration much matters at all in most defensive situations. You are not deer hunting, and the objective is not a carefully placed shot for a quick clean kill. You are trying to stop and attack by incapacitating him or causing him to flee. A bullet through a lung will certainly kill a man, and has a high likelyhood of being fatal, but may not necessary incapitate or stop an attack as fast as the shock you tranfer if you hit bone and/or double the projectile size and add blades around the edges. O guy with a small pass through hole through his lung can often pull a trigger many times before he dies.

[RickB]

Why are people so obsessed with penetration of hollow points?

Other than marksmanship, that's about my only concern. Expansion is nice; wound cavities, both temporary and permanent, are nice; but without marksmanship and penetration, the rest doesn't matter.
The concept of "overpenetration" puzzles me a bit, anyway.

[Madcap_Magician]

Originally Posted by tahunua001

I do not agree with the 16 inches necessary BS that the FBI recommends. unless you're shooting up from the floor vertically through the entire torso or you're taking on a body builder, you would never in a million years need 16 inches of penetration, the human heart lies meer inches from the rib cage in any direction, 6 inches would be lethal, and have little chance of overpenetrating but what do I know? I'm just some guy from the internet.

The reason the FBI protocol is for 12"-16" of penetration is because they are aiming for a worst-case scenario. It is actually not at all hard to come up with scenarios that are not even just possible, but likely, where you would need more than 6" of penetration.

First, a bullet may have to penetrate material in the way, such as heavy clothing. It may impact on more resistant body structures like bone. The person shot may be very large, whether muscle, fat, or both. And perhaps most commonly and importantly, a bullet that hits center mass may have to go through an arm on the way there, and it may be going through the long way on a transverse through the forearm.

[SHR970]

So many folks get way too hung up on the FBI 12"-16" number. They forget that the FBI protocalls also call for going through car windshields, car doors, heavy clothing, and other barriers and still achieving those numbers.

As a non LEO, there are precious few times where firing through a car windshield would be a justified shooting.

In an article in another thread the author referenced a 158 gr. 357 fired through a carbine only penetrating 10 or so inches and failing this depth standard. Personally, I doubt a 158 gr. XTP fired at around 2000 fps. at 50 yards or less is going to fail to do the job simply because it failed to make the FBI last two inches.

Even from a handgun, a full energy dump into the agressor is still a full energy dump. Hitting the CNS, causing shock, hitting major arteries / veins, psycological stops, etc. are some of the things that "Stop" and attack.

22's have stopped attacks...but don't count on it. 45's have stopped attacks...but don't count on that either.