Why Does Penetration matter?

This is a discussion on Why Does Penetration matter? within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; In all the research I've done so far online, it seems that most tests focus on the penetration depth and the expansion. Why does penetration ...

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Thread: Why Does Penetration matter?

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    Member Array CyanLite's Avatar
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    Why Does Penetration matter?

    In all the research I've done so far online, it seems that most tests focus on the penetration depth and the expansion. Why does penetration matter? It seems like 12 inches is the holy grail, however wouldn't that be TOO much for the average human tissue for a SD round? I'm a pretty big guy, but the width of my chest is no more than 10 inches, center of mass area.

    Wouldn't 12+ inches end up causing the round to exit and have the possibility of hitting someone behind the target?

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    You need to get the round in deep enough to hit something vital, but don't want it to go so deep that it overpenetrates, as you noted. Rounds do a lot of odd things during their terminal ballistics. You also need to keep in mind things like clothing the target is wearing, and the fact that most of the vital stuff you want to hit is protected by bone (either the rib cage, or the skull). It also seems that a lot of times bullets get deflected inside targets, and seldom take a straight path through, (in my observations at least). The 12 inch "holy grail", I believe refers to tests the FBI has done to find which caliber they want their agents to carry. And 12" of ballistics gel is what they determined they needed the bullets to penetrate in order to effectively incapacitate threats.
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    kpw
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    12 inches is the correlation to the human body in ballistic gelatin, not what it's supposed to do in a human body.
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    VIP Member Array Cuda66's Avatar
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    Quote Originally Posted by kpw View Post
    12 inches is the correlation to the human body in ballistic gelatin, not what it's supposed to do in a human body.
    ^^This.

    The reason that 12" is considered the minimum penetration depth is that rounds that penetrated at least to that depth in gel tests were shown to reliably penetrate vitals in actual shootings.

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    " I'm a pretty big guy, but the width of my chest is no more than 10 inches, center of mass area."

    I with you on this. Once a bullet has penetrated an inch or two of skin/fat, it's into the "vitals." They tend to make it sound like your vitals are protected by a 12" layer of human armor.

    Of course, more penetration equals more damage, and someone determined that 12 inches is the standard by which all calibers must be tested for effectiveness. I'm sure there are a lot of dead people that weren't penetrated 12 inches. I think the fear of a bullet penetrating a body and killing innocent bystanders is a bit mythical. It's probably happened, but is a rarity.

    It's kind of like comparing all motor vehicles by their miles per gallon ratings. But we know there's more to vehicles than just gas mileage.
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    Why is 70 a passing grade on most tests? Because someone decided it should be. The magic 12" originated in the "failure" of the 9mm Silvertip in the 1986 Miami FBI Shootout. The BG was hit in the bicep, bullet entered the chest cavity , went 10" and stopped 2" from the BG"s heart.

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    Take a look at the ICE-QT target (Immigration and Customs Enforcement - Qualification Target). It depicts a big ugly bad guy pointing a revolver at you, pretty much life-size. Notice how the vitals in the high chest cavity are shielded by the gun, hands, and arms. Your bullet needs to penetrate all that before even reaching the chest cavity...then it needs to go all the way through the chest, and hopefully sever the spine.

    That's why shot placement is king, and penetration is queen. If expansion happens at all, it is merely icing on the cake.

    Not all shots are full-frontal shots either. Shots from the side, or high or low angles, need to penetrate further that a full-frontal level ground shot.

    The FBI standard is minimum 12 inches in gel, with 15 preferred.

    Hope that helps!
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    Quote Originally Posted by OldVet View Post
    " I'm a pretty big guy, but the width of my chest is no more than 10 inches, center of mass area."

    I with you on this. Once a bullet has penetrated an inch or two of skin/fat, it's into the "vitals." They tend to make it sound like your vitals are protected by a 12" layer of human armor.

    Of course, more penetration equals more damage, and someone determined that 12 inches is the standard by which all calibers must be tested for effectiveness. I'm sure there are a lot of dead people that weren't penetrated 12 inches. I think the fear of a bullet penetrating a body and killing innocent bystanders is a bit mythical. It's probably happened, but is a rarity.

    It's kind of like comparing all motor vehicles by their miles per gallon ratings. But we know there's more to vehicles than just gas mileage.
    Again...12" of gel penetration is not necessarily 12" of human penetration. But even when it is--one cannot fail to consider oblique shots, shots that must first penetrate an arm (a common occurrence in SD shootings), or a shot that requires both--measure from the outside of your right bicep to your heart, and you may be surprised to find it's 12" or more (mine's just a hair over 15", but I'm a big guy). The odds of your target in a SD shoot looking like a paper silhouette--arms to the side, chest squarely presented--are pretty darn low.

    But let's hear what the experts say on the matter...

    Originally Posted by DocGKR
    I am not sure what a jello shooter is, but I can state that a variety of equally important methodologies are used for terminal performance assessments, including actual shooting incident reconstruction, forensic evidence analysis, and post-mortem data and/or surgical findings; properly conducted ethical animal test results; and laboratory testing--this includes the use of tissue simulants proven to have correlation with living tissue. Some individuals seem to be under the mistaken impression that one of these areas is more important than others--this is not the case, as each category provides important information. The last several years of OCONUS GWOT operations have given us a tremendous amount of combat derived terminal performance information. After analyzing all the available evidence from shots into living human tissue, the Joint Service Wound Ballistics IPT reported in the Summer of 2006 that then best measure of terminal performance and the only one concordant with battle field projectile injuries was properly interpreted, calibrated 10% ordnance gelatin. In LE, there is also great value in the use appropriately gathered and interpreted surgical and/or post-mortem data. The IWBA published some of Gene Wolberg’s material from his study of San Diego PD officer involved shootings that compared bullet performance in calibrated 10% ordnance gelatin with the autopsy results using the same ammunition. When I last spoke with Mr. Wolberg in May of 2000, he had collected data on nearly 150 OIS incidents which showed the majority of the 9mm 147 gr bullets fired by officers had penetrated 13 to 15 inches and expanded between 0.60 to 0.62 inches in both human tissue and 10% ordnance gelatin. Several other agencies with strong, scientifically based ammunition terminal performance testing programs have conducted similar reviews of their shooting incidents with much the same results--there is an extremely strong correlation between properly conducted and interpreted 10% ordnance gelatin laboratory studies and the physiological effects of projectiles in actual shooting incidents. There is a reason why LE agencies such as the FBI, California Highway Patrol, RCMP, etc… continue to rely on properly conducted gelatin studies when selecting ammunition.

    http://www.m4carbine.net/showpost.ph...6&postcount=46
    OldVet, with all due respect--I've read enough of your posts on this subject to see that you seem to think that as long as one gets a properly placed hit, it'll be good enough, and your assailant will just give up at that point. I am not nearly enough of an optimist to assume that.

    Shot placement is king, yes. But penetration is queen, and a wide wound channel is the ace in the hole.
    Last edited by MattInFla; August 1st, 2010 at 09:09 AM. Reason: Added a link to the source
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    Quote Originally Posted by Cuda66 View Post
    Again...12" of gel penetration is not necessarily 12" of human penetration. But even when it is--one cannot fail to consider oblique shots, shots that must first penetrate an arm (a common occurrence in SD shootings), or a shot that requires both--measure from the outside of your right bicep to your heart, and you may be surprised to find it's 12" or more (mine's just a hair over 15", but I'm a big guy). The odds of your target in a SD shoot looking like a paper silhouette--arms to the side, chest squarely presented--are pretty darn low.

    But let's hear what the experts say on the matter...



    OldVet, with all due respect--I've read enough of your posts on this subject to see that you seem to think that as long as one gets a properly placed hit, it'll be good enough, and your assailant will just give up at that point. I am not nearly enough of an optimist to assume that.

    Shot placement is king, yes. But penetration is queen, and a wide wound channel is the ace in the hole.
    ^^ THIS ^^

    Covers the topic pretty well.

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    Very well said, Cuda.
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    You have to understand that the 12" of penetration is established by shooting into a block of ballistic gelatin which is one single consistent density throughout the entire block of gelatin.

    The human body is not a single consistent density of mass throughout. For example, there are a lot of hollow cavities within the chest and abdominal area's of the body. The abdominal cavity is protected by the skin on the outside, followed by a varying level of fat, and then below that is not just a single layer of hard fibrous muscle tissue, but several layers of hard fibrous muscle tissue. Not only that, but the weave, or "grain" of the musculature layers run in different directions which leads to varying amounts resistance to penetration in much a similar way that soft body armor works and the way the cross grain lamination of a sheet of plywood gives it it's strength and resistance. Once inside the actual abdominal cavity, there are both hollow and solid organs, all of which has a different density. Within the chest cavity, you have hard bony structures such as ribs, scapula's, sternum, etc. which are a physical barriers and can literally stop a bullet in it's path or frequently deflect the path the bullet travels.

    So, you can see, the human body is hardly the single consistent density which you see in a solid block of ballistic gelatin. What the FBI determined in their study of acceptable penetration for ammunition carried by their agents is that a bullet which can consistently penetrate 12" - 14" of ballistic gelatin is likely of sufficient penetration value to overcome the various density of tissue, bone and other factors in the human body to allow it to reach the vital organs.

    While a bullet may only need to penetrate a depth of 3" or so to reach the heart from a frontal shot, it may have to be able to punch through a think and hard 1" layer of bone in order to reach the heart. Or it may have to penetrate a 1.5" rib bone and then an additional 6" or 7" of lung tissue before it hits the heart from a shot entering from the right side of the body.

    This is why we often see cases where someone shot in the forehead with a .25 acp bullet which only may consistently penetrate 6" or 7" in ballistic gelatin can sometimes fail to penetrate the skull and merely travel around the outside of the skull, below the skin and exit out toward the back of the head having merely traveled along the outside of the skull and only causing superficial bleeding and soft tissue damage. However that same bullet if shot into the extremely thin and fragile temporal bone portion of the skull from the side, may easily penetrate deep into the brain.
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    Why Does Penetration matter?
    Cuda and Bark'n covered it fairly well. It comes down to the fact that predators aren't static ballistic gel blocks.

    If all targets were walking, talking ballistic gel blocks and struck head-on, then it would be a simple exercise to say that penetration of X inches was sufficient and the end-all, be-all standard. Life's not that simple. Predators move, wear different clothing and otherwise make it very difficult to strike them head-on with reliability. And so, anything attempting to penetrate to vital organs must ensure that it can get through multiple layers of clothing, one or more bones, and very likely more depth than the "standard" suggests is minimally sufficient.

    As well, merely poking a hole at depth is fine, but it's not sufficient to quickly stop a predator with any great frequency. Rather, it's important to tear up the body's ability to continue functioning if a person's going to be assured of stopping the predator. Even then, there are no guarantees, given that many are coked-up, methed-up or amped in some other way.
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    ThIs is why I load my guns with magic bullets

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    I never said penetration wasn't important. I said, "Of course, more penetration equals more damage..." It's just not the knock-'em-off-their-feet answer so many tout.

    Rebel Rabbi:
    "The BG was hit in the bicep, bullet entered the chest cavity , went 10" and stopped 2" from the BG"s heart. "

    So in fact, taking the width of the bicep into consideration, that bullet did penetrate at least the magical 12 inches. Maybe the FBI needs to increase the standard to 15...20 to account for biceps, hands, clothing, and anything else that may get into the way.

    Many people have walked away from a thru-and-thru while many others have dropped dead in their tracks from a shot that penetrated 6-8 inches. If I'm shot in the chest and the bullet only penetrates 8 inches, No doubt I'm coughing up blood. A ragged bullet in the heart can cause as much or more damage than one passing thru.

    Given my preference, I'd use no less than a .44 Magnum for SD protection, but practicality precludes that. A .380 is a very accurate and controlable round with a capable firearm and shooter, but it's lighter powerwise than what I care to carry. Nor would I opt to use my light range loads for SD, but I would if that's what was in the firearm at the time I needed to.

    Seeing as most brand-name SD rounds penetrate roughly the same amount (to meet FBI standards) then wrapping one's butt around an axle over how much penetration they have is a mute point.
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    Quote Originally Posted by OldVet View Post
    I never said penetration wasn't important. I said, "Of course, more penetration equals more damage..." It's just not the knock-'em-off-their-feet answer so many tout.

    Rebel Rabbi:
    "The BG was hit in the bicep, bullet entered the chest cavity , went 10" and stopped 2" from the BG"s heart. "

    So in fact, taking the width of the bicep into consideration, that bullet did penetrate at least the magical 12 inches. Maybe the FBI needs to increase the standard to 15...20 to account for biceps, hands, clothing, and anything else that may get into the way.

    Many people have walked away from a thru-and-thru while many others have dropped dead in their tracks from a shot that penetrated 6-8 inches. If I'm shot in the chest and the bullet only penetrates 8 inches, No doubt I'm coughing up blood. A ragged bullet in the heart can cause as much or more damage than one passing thru.

    Given my preference, I'd use no less than a .44 Magnum for SD protection, but practicality precludes that. A .380 is a very accurate and controlable round with a capable firearm and shooter, but it's lighter powerwise than what I care to carry. Nor would I opt to use my light range loads for SD, but I would if that's what was in the firearm at the time I needed to.

    Seeing as most brand-name SD rounds penetrate roughly the same amount (to meet FBI standards) then wrapping one's butt around an axle over how much penetration they have is a mute point.
    Actually, the bullet RR was referencing went a total of about 10", hence the 12" minimum.

    As for the rest--the OP asked why it was important. We answered it. You seem to state, by your initial assertion that a bullet only penetrating 2-3" will be in vitals (doubtful, but possible), and that plenty of people had died taking rounds that only penetrated 6-8" (quite possible--but when did they die, and what were they capable of doing between the time of the hit and the time they expired? Lethality of a wound shouldn't be one's concern in a SD shoot--gettiing the bad guy to stop whatever they're doing to make you decide they need to be shot as rapidly as possible should), pretty much gives the argument that it's not that important...which is very similar to statements you've given in other discussions of this matter...and is just, well...wrong.
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