Total wound channel comparisons

[BuckskinJoe]

Permanent cavity appears to be the primary factor in handgun and shotgun projectile effectiveness; so, I did a few calculations on total wound channel for a few of handgun calibers, along with 00 buck and #1 buck.

I believe Dr. Roberts has stated that good 9mm ammunition expands, on average, to about 0.60" while .40 cal. expands to an average of 0.65" and .45 ACP to 0.70". Full expansion occurs in the first one-to-two inches of penetration; so, assuming full expansion for all penetration will not make a material difference.

With 12 inches of penetration in all cases, I get the following results:

17 rounds of 9mm give total wound channel of 57.7 cubic inches.
15 rounds of .40 cal. give total wound channel of 59.7 cubic inches, and
13 rounds of .45 ACP give total wound channel of 60.0 cubic inches.

One round of 3" mag. #1 buck (24 pellets) gives total wound channel of 20.4 cubic inches.
One round of 3" mag. 00 buck (15 pellets) gives total wound channel of 15.4 cubic inches.

Now, with the enormously heroic assumption that in a deadly force encounter a shooter can make all good hits, we get the approximate equalities:

18 rounds of 9mm, 15 rounds of .40 cal., 13 rounds of .45 ACP, 4 rounds of 3" 00 buck, and 3 rounds of 3" #1 buck all yield approximately the same total wound channel.

Another way of looking at it is: 6 solid hits with 9mm, 5 solid hits with .40 cal., 4 solid hits with .45 ACP, and one solid hit with 3" mag. #1 buck all have approximately equivalent total wound channel.

[Zhukov]

Interesting play with the numbers, but the big thing is the statistical probability of getting that subsequent hits goes down exponentially with each shot.

[BuckskinJoe]

Interesting play with the numbers, but the big thing is the statistical probability of getting that subsequent hits goes down exponentially with each shot.

Very intentionally, I did not make or imply any conclusions from the rather simple calculations, but I am inclined to agree that, generally, achieving "good hits" from subsequent shots tends to decrease in probability as shot count increases. However, some might proffer the controllability of a 9mm allows both faster and more accurate follow-up shots.

Personally, I lean toward the side of "bigger holes with fewer shots" mindset, and nothing compares with 12 gauge buckshot in that arena. Consequently, our primary home defense firearms are shotguns--my side of the bed has an 870, and my wife's side has an 11-87, both loaded with 3-inch #1 buck. Shotguns, however, are particularly lousy concealed carry firearms; so, she has a Glock 30 in .45, and I carry a Glock 27 in .40 (a bit easier to conceal.) I do have to put up with her teasing me about my .40 S&W (Short & Wimpy) handgun! :D

Regardless, the 6-5-4-1 wound-channel equivalency for 9mm, .40, .45, and 3-inch #1 buck seems to me to be a reasonable ballparker.

[DBR]

How did you determine the crush cavity diameter?

It's not as large as the bullet diameter in most cases and there are many variables. I don't think you can assume it is even proportional to the expanded diameter of the bullet and it changes with velocity.

[BuckskinJoe]

How did you determine the crush cavity diameter?

I believe the numbers are in my original post, but, if you missed them: 9mm--0.60" .40 cal.--0.65" .45--0.70"

For buckshot, I used the pellet diameters: 0.30" for #1 buck, and 0.33" for 00 buck.

Cross sectional area is calculated by pi-r-squared, and wound channel volume by multiplying by 12 inches. However, the depth of penetration has no effect on the relationship among the projectiles--it will remain 6-5-4-1 for 9mm. /40 cal./.45 ACP/3" #1 buck (24 pellets) regardless of the depth used.


It's not as large as the bullet diameter in most cases and there are many variables. I don't think you can assume it is even proportional to the expanded diameter of the bullet and it changes with velocity.

If your claim is correct, how much of a projectile's cross section does not produce wounding and does the proportion change for 9mm., .40 cal., .45 ACP and buckshot? What are the many variables that would change the relationships?

Also, your claim that permanent cavity cross section changes with velocity in handgun and shotgun projectiles is an interesting conjecture that I haven't encountered in reputable research I've seen. Furthermore, the velocities of all the projectiles I mentioned are all in the trans-sonic range with little difference among them.

I would be delighted to hear back with reputable data that invalidates the general permanent cavity comparisons I have calculated. It does seem to me that larger diameter projectiles will produce proportionally larger wounds than smaller projectiles and "x" many projectiles will produce "x" times the total wound channel with the same penetration.

[crossgun]

I don’t believe that the human body works in this manner to actually cause a "true" permanent wound cavity or carve out 100% channel. While I am sure the math is correct guess I don’t see the relevance.

It would be great if tissue reacted this way to bullets.

[NinjaMedic]

Could this be better calculated by measuring the volume of water you can pour into the ballistic gelatin after shooting it? With a large enough sampling you could probably get a fairly accurate approximation of the average total wound channel for each round. Has this been done before?

[BuckskinJoe]

Could this be better calculated by measuring the volume of water you can pour into the ballistic gelatin after shooting it? With a large enough sampling you could probably get a fairly accurate approximation of the average total wound channel for each round. Has this been done before?

That is an intriguing idea! My initial question is whether or not ballistic gelatin "retains" temporary cavity, which would skew the results.

Perhaps, Doctor Roberts will weigh in. Again, my whole purpose was to calculate "ballpark" estimates of the relative permanent cavity (crush) wounding capacities of some handgun and shotgun rounds--ceretis paribus. Large sample sizes of controlled experimental results, of course, would give a more accurate picture.

[crenca]

I had always assumed that expanding ammo (even in the case of the latest generation) was not consistent enough for anything but rough/general calculations like this. Still, you are not claiming anything more.

Also, what is the velocity of say #1 buck at 20 yards as opposed to 3? I would think the penetration of buck is very sensitive to distance (more so than pistol ammo).

[BuckskinJoe]

I had always assumed that expanding ammo (even in the case of the latest generation) was not consistent enough for anything but rough/general calculations like this. Still, you are not claiming anything more.

Also, what is the velocity of say #1 buck at 20 yards as opposed to 3? I would think the penetration of buck is very sensitive to distance (more so than pistol ammo).

I used the numbers, I believe, that Dr. Roberts published as average recovered diameters of the best performing current handgun ammunition along with the actual pellet diameters of 00 and #1 buck to get the best central tendency esitmates. #4 buck, because of the greater number of pellets, gives even greater total wound channel, but #4 buck, in gelatin tests, does not exhibit consistent penetration of 12 inches or more; so, I did not include #4 buck.

Agree with your premise that buckshot sheds velocity much faster than handgun bullets, but, for my purposes, in the home, I would never have a shot in excess of 5 yards. Also, I simplified the comparisons by not considering the first portion of handgun bullet penetration before complete expansion, and I did not consider the additional wound channel produced by the wad cup at short ranges in shotgun rounds

[tpd223]

Regardless of how much tissue a particular round crushes, it must still hit something vital to be effective.

In a recent street shooting we had a young lady was shot with a full power Foster style slug at very close range, although she lost about half of her left hamstring muscle from the hit, leaving an entrance wound over 2" and an exit that was about 8"X6" across, she didn't even know she was shot until after she ran away from the shooter and then started to notice she was bleeding.

Anyway, carry on.

[DBR]

BuckskinJoe:

What I posted is based on my reading Duncan MacPherson's 2005 book "Bullet Penetration".

There is a lot of math involved and nothing simple enough I can quote except the "shape factor". Bullets of differing shapes crush tissue more or less efficiently.

With respect to velocity: as the velocity increases above a threshold a bullet with a particular "shape factor" crushes more (or less) tissue per unit penetration for a given actual size and shape.

[NinjaMedic]

I need to educate myself more on BG and exactly how it responds to projectiles as a substance and maybe DocGKR has some thoughts however it would seem to me that a scientific volumetric analysis of the permanent cavity created would be a valuable indicator of a projectiles performance. It would seem that a internal displaced volume measurement or even 3D rendering of the BG post impact could yield valuable information much more precisely than (from my understanding) purely external measurements that are being performed. Especially now with "virtual autopsies" via CT/MRI becoming increasingly popular you could make similar measurements and images of actual GSW's and compare the data more precisely. Compare the actual 3d wound track with the predicted ones could allow us to more precisely understand how a projectile will perform inside of the body at various velocities, angles of attack, etc., along with how the internal structures influence the terminal ballistics. Maybe this is already being performed I dont know but I bet DocGKR or someone else would know and have a more informed opinion.

[panzerr]

Regardless of how much tissue a particular round crushes, it must still hit something vital to be effective.

In a recent street shooting we had a young lady was shot with a full power Foster style slug at very close range, although she lost about half of her left hamstring muscle from the hit, leaving an entrance wound over 2" and an exit that was about 8"X6" across, she didn't even know she was shot until after she ran away from the shooter and then started to notice she was bleeding.

Anyway, carry on.

She lost half her hamstring and managed to run away?

She may not have known she was shot due to shock, but I doubt she did much running with that much leg muscle gone.

[MK108]

...I guess that apart the larger mass of tissue crushed by the pellets of a single buckshot round compared to pistol ammunition....these pellets on penetrating the living target have much better chances to damage important structures and organs inside the body than a single projectile...

All the best
Andrea

[DrJSW]

I need to educate myself more on BG and exactly how it responds to projectiles as a substance and maybe DocGKR has some thoughts however it would seem to me that a scientific volumetric analysis of the permanent cavity created would be a valuable indicator of a projectiles performance. It would seem that a internal displaced volume measurement or even 3D rendering of the BG post impact could yield valuable information much more precisely than (from my understanding) purely external measurements that are being performed. Especially now with "virtual autopsies" via CT/MRI becoming increasingly popular you could make similar measurements and images of actual GSW's and compare the data more precisely. Compare the actual 3d wound track with the predicted ones could allow us to more precisely understand how a projectile will perform inside of the body at various velocities, angles of attack, etc., along with how the internal structures influence the terminal ballistics. Maybe this is already being performed I dont know but I bet DocGKR or someone else would know and have a more informed opinion.

I don't wish to stifle meaningful discourse, but this sort of discussion is akin to the medieval scholars' debates about how many angels can dance on the head of a pin.

A wound channel in the human body is not a simple cylinder, but rather a complex shape that, as others have pointed out and as Duncan Macpherson mathematically elucidated, is shaped by the meplat of the bullet (which, in expanding bullets, changes as it courses through tissue) and its velocity. Even if you were able to use an MRI to precisely measure the dimensions of a specific GSW tract in, say, a medical cadaver--and frankly, most MRI's aren't that precise for this sort of thing--you would get an entirely different wound profile if you varied the angle of incidence by 5 or 10 degrees, or changed the point of impact 2 centimeters to the left. The volume of the permanent cavity is also going to vary depending on what tissues it passes through, as some tissues are more elastic than others, and due to this elasticity, the actual vascular surface area exposed by the GSW will not bear a reliable relationship to the volume of the cavity.

Ballistic gelatin testing utilizes a homogeneous medium to determine how well ammunition performs when compared to all other types of ammunition. Ballistic gelatin wound channels do NOT approximate or predict the conformation of wound channels in heterogeneous tissue. As such, attempting to quantify the "wounding effectiveness" of one round vs another by arithmetical gymnastics or by pouring water into a gelatin wound cavity is unlikely to yield any meaningful information.

Incapacitation by pistol/shotgun GSW is, at bottom, a function of what specific anatomic structures are penetrated or perforated by the projectile(s), and the degree of tissue destruction caused thereby. As such the serious student of GSW's and incapacitation is better served by the study of human anatomy and physiology, learning the anatomic relationships of the vital structures in three dimensions, and simultaneously putting in some serious training time to master the application of his/her service handgun.

There are only two reliable and consistent means of incapacitation by gunshot wound: central nervous system destruction, and exsanguination (blood loss leading to catastrophic drop in blood pressure, which shuts down the CNS). In order to take out the CNS, you have to have accurate shot placement. In order to shut down the central portions of the circulatory system, you have to have accurate shot placement. If you have accurate shot placement and you are using good expanding ammunition, you will incapacitate your adversary whether your firearm is a 38 Special or a 45 ACP. The volume of the wound channel your bullet makes is of no consequence provided you put your bullets where the vital structures necessary to sustain life reside. DocGKR's sticky on service handgun calibers at the top of this forum addresses this from a ballistician's viewpoint. Perhaps you can consider this an answer from a trauma physician's and research physiologist's viewpoint.

There are other means of incapacitation by GSW such as psychological incapacitation, neural stunning, and musculoskeletal system destruction, but these are not reliable or consistent.

For a much more cogent and comprehensive discussion of these issues, you should re-read DocGKR's sticky, here:

https://www.m4carbine.net/showthread.php?t=34714

[DocGKR]

Dr. Williams is right on target, so to speak. Don't get bogged down in minutia. For example, please do not pour water or other material into the gel blocks--it does not offer any meaningful data and only serves to obfuscate the important parameters. Post mortem imaging is a useful overall adjunct, but not for exact calculations of wound volume--it does let us know that properly interpreted current lab testing offers a very good correlation with actual shooting incident results. From an end-user stand point, it is far more important to ensure you have a good mindset, choose a reliable weapon system, pick a quality load, get extensive training, then practice...a lot.

[tpd223]

"She lost half her hamstring and managed to run away?

She may not have known she was shot due to shock, but I doubt she did much running with that much leg muscle gone."

You can doubt all you want to, that's exactly what happened. She lost so little ability to walk/run that she had no idea anything was wrong until she noticed that she was bleeding all over the place.

She did have, being nice here, alot of thigh. She is rather a thick girl.



Docs,

Thanks for the reality check posts.

[DrJSW]

[QUOTE=tpd223;437415] She did have, being nice here, alot of thigh. She is rather a thick girl. QUOTE]

Nicely put.

An anatomical note: the "hamstrings" are actually two separate muscles, the semimembranosus and the semitendinosus. They function separately, with separate innervation and circulation. It would indeed be possible for an adrenalized person to run with one of the two muscles shot up.

[BuckskinJoe]

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In order to shut down the central portions of the circulatory system, you have to have accurate shot placement. If you have accurate shot placement and you are using good expanding ammunition, you will incapacitate your adversary whether your firearm is a 38 Special or a 45 ACP.
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.
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Questions for DrJSW:

1) Is good expanding ammunition required for incapacitation, or is such possible with non-expanding round nose or FMJ bullets?

2) With accurate shot placement, is it possible with a typical, round nose .22 long rifle round to achieve incapacitation?

3) If incapacitation is NOT possible with a typical .22 long rifle bullet, regardless of shot placement, what, then, is the minimum required handgun cartridge and bullet to achieve incapacitation?

4) Since accurate shot placement is required for incapacitation, is there any reason to use a caliber/cartridge larger than the .22 long rifle (or the minimum required caliber/bullet that can cause incapacitation with accurate shot placement.)

5) Again, since accurate shot placement is required for incapacitation, is there any reason to fire more than one shot with the minimum required caliber/cartridge capable of incapacitation?

[Glock17JHP]

Personally, I lean toward the side of "bigger holes with fewer shots" mindset, and nothing compares with 12 gauge buckshot in that arena. Consequently, our primary home defense firearms are shotguns--my side of the bed has an 870, and my wife's side has an 11-87, both loaded with 3-inch #1 buck.

Ummm... how well do you both shoot those loads??? OUCH!!! :confused:

[tpd223]

Questions for DrJSW:

1) Is good expanding ammunition required for incapacitation, or is such possible with non-expanding round nose or FMJ bullets?

2) With accurate shot placement, is it possible with a typical, round nose .22 long rifle round to achieve incapacitation?

3) If incapacitation is NOT possible with a typical .22 long rifle bullet, regardless of shot placement, what, then, is the minimum required handgun cartridge and bullet to achieve incapacitation?

4) Since accurate shot placement is required for incapacitation, is there any reason to use a caliber/cartridge larger than the .22 long rifle (or the minimum required caliber/bullet that can cause incapacitation with accurate shot placement.)

5) Again, since accurate shot placement is required for incapacitation, is there any reason to fire more than one shot with the minimum required caliber/cartridge capable of incapacitation?



Why do you want to ask questions that are just short of stupid as hell, especially from a guy as busy as the good Doc?

Of course one can use a .22 for defense, or RN nonexpanding ammo, but that would be a poor decision if one had other choices, hence why we pre-plan our responses.

Good quality service caliber handgun ammunition helps insure that a reliable wound to the vital structures we need to hit to stop a bad guy actually get damaged.
Due to the nature of how small caliber bullets penetrate (unreliably), and how RN ammo functions, terminally speaking, they do not give us these advantages.

Since no one on the planet is good enough to ensure a solid hit the first try, and even then it is best to shoot until we know the threat is stopped, obviously firing more than one round will likely be called for.

[BuckskinJoe]

I asked...

Questions for DrJSW:

1) Is good expanding ammunition required for incapacitation, or is such possible with non-expanding round nose or FMJ bullets?

2) With accurate shot placement, is it possible with a typical, round nose .22 long rifle round to achieve incapacitation?

3) If incapacitation is NOT possible with a typical .22 long rifle bullet, regardless of shot placement, what, then, is the minimum required handgun cartridge and bullet to achieve incapacitation?

4) Since accurate shot placement is required for incapacitation, is there any reason to use a caliber/cartridge larger than the .22 long rifle (or the minimum required caliber/bullet that can cause incapacitation with accurate shot placement.)

5) Again, since accurate shot placement is required for incapacitation, is there any reason to fire more than one shot with the minimum required caliber/cartridge capable of incapacitation?






Why do you want to ask questions that are just short of stupid as hell, especially from a guy as busy as the good Doc?

Of course one can use a .22 for defense, or RN nonexpanding ammo, but that would be a poor decision if one had other choices, hence why we pre-plan our responses.

Good quality service caliber handgun ammunition helps insure that a reliable wound to the vital structures we need to hit to stop a bad guy actually get damaged.
Due to the nature of how small caliber bullets penetrate (unreliably), and how RN ammo functions, terminally speaking, they do not give us these advantages.

Since no one on the planet is good enough to ensure a solid hit the first try, and even then it is best to shoot until we know the threat is stopped, obviously firing more than one round will likely be called for.

Thank you for your response and kind words, sir, but the questions were not addressed to you. Unless DrJSW has designated you as his spokesperson, please allow him to respond if he so chooses.

[BuckskinJoe]

Originally Posted by BuckskinJoe
Personally, I lean toward the side of "bigger holes with fewer shots" mindset, and nothing compares with 12 gauge buckshot in that arena. Consequently, our primary home defense firearms are shotguns--my side of the bed has an 870, and my wife's side has an 11-87, both loaded with 3-inch #1 buck.



Ummm... how well do you both shoot those loads??? OUCH!!! :confused:

Hey, thanks for asking. Actually, we do quite well. My wife is very unusual in that she likes heavy loads and recoil. The last time we shot, she had five well-placed shots (three to COM and two to the head) in very rapid fire with the 11-87. The 870 kicks harder than the semi-auto, but I don't mind it too much, unless I am firing 30 to 40 rounds at a shotgun match. At that point, my cheek and shoulder cross the OUCH threshold! If we ever have to use them in defense, the last thing we will notice is recoil.

[DrJSW]

Questions for DrJSW:

1) Is good expanding ammunition required for incapacitation, or is such possible with non-expanding round nose or FMJ bullets?

2) With accurate shot placement, is it possible with a typical, round nose .22 long rifle round to achieve incapacitation?

3) If incapacitation is NOT possible with a typical .22 long rifle bullet, regardless of shot placement, what, then, is the minimum required handgun cartridge and bullet to achieve incapacitation?

4) Since accurate shot placement is required for incapacitation, is there any reason to use a caliber/cartridge larger than the .22 long rifle (or the minimum required caliber/bullet that can cause incapacitation with accurate shot placement.)

5) Again, since accurate shot placement is required for incapacitation, is there any reason to fire more than one shot with the minimum required caliber/cartridge capable of incapacitation?


Given your choice of bedside home defense weapons, I have to wonder why you are asking these questions.

First, I recommend you re-read Dr. Roberts' sticky post on service caliber handgun ammunition:

https://www.m4carbine.net/showthread.php?t=19887


Unless one lives in New Jersey or a jurisdiction outside the USA that prohibits use of JHP ammunition, one should always use the best quality JHP ammunition available. I believe it's wise to select a caliber and cartridge that is commonly used by law enforcement in duty handguns, which means 38 Special or 9mm at minimum.

The defensive-minded private citizen should select the handgun caliber they can shoot best, select good quality JHP ammunition, and get the best training in use of the firearm and in the use of deadly force they can afford. There are several outstanding trainers who truly know and understand use of deadly force by private citizens and can communicate it effectively, including John Farnam, Clint Smith, and Massad Ayoob. Anyone who keeps a firearm for home/personal defense needs such training. Thereafter, the wise defensive-minded person needs to train regularly with their chosen firearm(s) and ammunition.

Finally, as to the number of rounds that need to be expended: shoot to stop the threat, and don't stop shooting until the threat has been stopped.

"Don't shoot your enemy until you think he's dead; keep shooting him until he thinks he's dead."

- quote from a friend who has been on the sharp end of the spear for several decades.