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Discussion in 'Caliber Corner' started by glock20c10mm, Jan 15, 2010.
I decided to go to Bullet Test Tube's web site. Here's what I found:
That's the point I'm making.
The point I am making is that there is no way a bullet physically displaces anything beyond the .8" or whatever that it expands to. How could it? If it doesn't touch it, how is it "physically displacing" it?
Ergo, this medium is giving you a false sense of "damage" by measuring part of the temporary cavity. You can see temporary cavity in dyed gel. It's very VERY near the same for .45 and for 357SIG.
If it's very near, I'll take 14 rounds over 9 anytime. I can now buy practice ammo for the .357 sig cheaper than .45.
Wow. If you don't mind, where are you finding 357SIG cheaper than $15/50? That is the going rate for Federal .45 230 FMJ here.
It's been a long time. Good to see folks like Fastbolt are still around.
Regarding Dr. Roberts ... yes, he is a dentist. IIRC, he performs reconstructive surgery as a specialty. He's also respected by many as a ballistics expert who has been contracted to test for some of the nations largest LE agencies as well as various military operations (to include MEU's), etc. In addition, Dr. Roberts has attended/observed shooting related autopsies and was also a Naval officer as well as a LE officer.
As far as the IWBA/FBI testing protocol ... it has quite simply, had a profound impact on ammunition as we know it today. Every major ammunition manufacturer has bent over backwards to meet the specifications of the IWBA/FBI when it comes to their top of the line duty ammunition. And in doing so, there has been some excellent loads developed as a result. Loads like: Speer Gold Dot ... Federal HST ... Winchester Ranger ... etc.
Testing conducted through various inanimate barriers such as clothing, plywood/drywall, windshields, car panels, etc... is certainly relevant, given the fact that bullets in the real world must most often first pass through one or more of these inanimate barriers prior to striking the primary target.
and here I thought Glock Talk was populated only by the Courtney fanatics.
I'm not necessarily a fanatic of anyone. However, I do respect Dr. Roberts work. One thing I like ... is that he doesn't necessarily favor light & fast or slow and heavy (ah, the debates of old, lol). While he may prefer larger rounds overall for their potential ability to crush more tissue ... he seems to primarily go by how a given round performs in testing. He recommends everything from the lightweight 9mm Corbon DPX ... to the heavyweight 230gr. Wincher Ranger T.
Additionally, it's simply hard for me to ignore the fact that all of the major ammunition makers strived to meet the IWBA/FBI testing protocol when designing their top of the line duty ammunition; and the results have produced some outstanding loads. Irrespective of service caliber chosen ... when talking about loads like Winchester Ranger T-Series and Federal HST, they all perform well at various weights and velocities. So do loads using the DPX bullet, etc.
The .40 S&W, and in particular the 357 sig ... came along at a time when bullet technology really started making strides. That may have something to do with their 'street' success. Lackluster ammunition from days gone by are plentiful in 9mm and .45 ACP. Current bullet technology has allowed all of the service calibers to perform better.
I fully agree. There really were no junk .40 or 357SIG rounds like there have been in other calibers due to technology.
Right, as long as a given bullets end result meets IWBA/FBI testing protocol he'll tell you it's a good bullet in whatever load it was launched from. Nothing wrong with that in my mind.
My problem is that Dr. Roberts claims all of Dr. Courtney's work reguarding enough peak BPW and it's effects toward incapactation some percentage of the time is complete BS, yet will never gives reasoning why. Not ever. He simply states he and a number of collegues looked over Dr. Courtney's studies and found it to be full of holes. Yet he won't point to a single supposed hole, and he has been asked directly a number of times when he choose to get involved in threads reguarding Dr. Courtney's theory of BPW. He has also made mention in threads on GT when asked direct questions that he ignored that he isn't interested in wasting time with anyone he didn't ask a direct question to.
And of course it was Dr. Martin Fackler who was the deciding factor behind much of the IWBA's work in terms of what ended up being termed FBI protocol. Dr. Roberts simply rode on Dr. Facklers coat tails. Not to mention Dr. Fackler has had some pretty negative comments toward Dr. Roberts which may or may not be beside the point.
So again, no doubt Dr. Roberts is an intelligent man, but it doesn't mean he isn't closed minded toward new theories like Dr. Courtney's with plenty of research behind it to back it up. Therefore, IMO, Dr. Roberts leaves some to be desired. Duncan McPhearson, it seems to me, actually did more different supporting work to Dr. Facklers than Dr. Roberts could have ever dreamed of doing.
And yeah, Dr. Roberts may have been contracted to test for some of the nations largest LE agencies as well as various military operations, but so what? Anyone could have done it that had the resources. All he had to do was test it going by the FBI protocol that already existed.
Now a days you can simply call up the likes of ATK among others who have the resources to do the testing (now mobile) and they'll bring it to wherever you want to test your ammo including any ammo you want to test against their Speer and Federal brands.
At the end of the day I don't see Dr. Roberts being as helpful as many are lead to believe. He wouldn't have had to exist for us to know the vast majority we do, and he chooses to be closed minded to Dr. Courtney's work which has zero supporting evidence against it. Therefore I don't hold him in the high reguard so many others do, then again, most others don't know what I know.
That has little to do with Dr. Roberts directly.
PS - This was simply my opinion based on a certain amount of fact. Please don't take it negatively toward yourself as I have nothing against you. Just throwing my thoughts out there.
You have told us in other posts about the years you have spent in a science degree studying experimental design. I have to wonder what kind of degree this was and what kind of university ran it.
If I were to punch you in the face when you were standing with the back of your head 6 inches from a wall and the back of your head then bounced off the wall, would the back of your head not have been physically displaced by my punch? Yet I have not touched the back of your head and I would no longer be in contact with your face by the time your head hit the wall. I am at a loss to understand what you might mean by "physical displacement" and why you think that the tissue pushed outwards from the bullet track is not physically displaced by the bullet.
You say, "You can see temporary cavity in dyed gel." If you think about it you might realise that the temporary cavity is what it says on the tin. It is not just temporary, it is very temoprary. So if dye has been put into the cavity it has been done after the temporary cavity has collapsed and what you see is not the temporary cavity but the permanent cavity and the infiltration of dye into the tears created by the temporary cavity. You can get an idea of the size of the temporay cavity by high speed photography or high speed moving photography of the bulge in the outside of the gel block as the temporary cavity briefly expands and collapses.
You seem to think that ballistic gelatin is representative of human flesh. This is a remarkably naive concept for a scientist. It has been developed and adjusted to model just one aspect of human flesh. That is, it has been developed to provide approximately the same average resistance as flesh so that the depth of penetration of bullets can be measured in a repeatable way in a consistent test medium to give an approximatley one to one relationship to their penetration in real people. As it does this, it also produces a similar degree of bullet expansion.
If you try to extend the gel model beyond this, it fails. Its tensile strength is not the same and so its resistance to the expansion of the temporary cavity is not the same. The tears is the gelatin block cannot be the same as the tears in real flesh. Even the permanent cavity cannot be the same since part of the size of the permanent cavity in flesh is a result of the bursting of cells and gelatin has no cells to burst so the mode of disruption has to be different.
The size of the temporary cavity is a function of both the rate of displacement needed by the bullet for it to move through the medium at its instantaneous speed and the resistance of the medium to that displacement. That displacement depends on the tensile strength and power of the medium and the mass being displaced. Its tensile strength allows it to tear or resist tearing and its tensile power allows it to act like a spring resisting deformation by storing and then releasing deformational energy.
The greater the mass surrounding the displacement the greater the inertial resistance to deformation. This mass can come from the density of the material of from the size of the block. A bigger block will have greater resistance to the formation of a temporary cavity. Since such resistance will increase the hydrodynamic pressure in front of the bullet, it will slow it faster, expand it further and reduce its penetration. The rate of expansion of the temporary cavity can be such with a high energy bullet that it bursts the gelltin block and so reduces the hydrodynamic pressure and increases the penetration.
It is obvious that ballistic gelatin must have a standardized formulation and consistency. This is made clear by the fact that it has to be used at a very closely controlled temperature. It should also be clear from the above that any testing via ballistic gelatin can be standardized only with a standard size of block but that such a block will work only within a limited window of rates of energy release. That is, a block size and consistency which has been validated on normal service pistol rounds will become progressively less valid for rounds outside that window. In order to validate the Ballistic gelatin block size and composition it had to be tested agains lots of real world results. That was almost certainly 9mm bullet wounds since they were the most readily available from battlefield autopsies. This has significant implications. If ballistic gelatin is approximately valid for 9mm is will become less valid as we move down to .380 and then .32 or up to 357SIG, 10mm, .44 Mag and so on. As we get to .454 Casull and upwards we can think of it as nearly worthless. Ballistic Gelatin is not a gold standard of universal constancy but a rough and ready means of comparing relative bullet performance in the region of 9mm rates of energy transfer.
So, if we look at the Bullet Test Tube, we should look at it in the same cynical manner. We cannot expect it to model flesh and bone and can expect little morre than a guide to some aspects of bullet performance. The thing it gives the greatest comparative result to is the temorary cavity and it does this precisely because it does not collapse back into shape in the way the ballistic gelatine does. (I imagine this is not entirely true since the containing tube will probably collapse it to some extent.)
This then brings us to the issue of the wounding effect relative to the sive of the temporary cavity. It is hard not to be impressed by the size and violence of the temporary cavity shown in ballistic gelatin in slow motion movies though some people seem to manage this feat without difficulty. We can see a similar impressive bulge of tissue caused by bullets shot into dead human or animal bodies and it seems obvious to me, though not to many, that such a bullet wound must incapacitate a considerable volume of tissue outside the permanent cavity to a decreasing extent as the distance from the bullet track increases. I find this a fascinating subject but I have spent enough time on this for now.
I meant to bring this up earlier. Well said.
The BTT has no correlation to flesh, and the makers of it don't care. The only thing it is good for is telling you how a bullet performs in the BTT, with regard to "TC" in the BTT. Beyond that, any correlation has not been defined. Due to the inelaxtic nature of the substance, it would seem pointless to compare it to an animal or human.
Craig, no harm done.
Only Dr. Roberts can answer why he considers the work of Dr. Courtney to be complete 'BS' as you stated. Personally, I would look at it this way: if my load already performed to protocol AND I could also potentially obtain another wounding mechanism via BPW, so much the better. While I may not switch to say a faster load (if necessary) soley to potentially achieve BPW ... I would have no problem at all if a certain load I was comfortable with and carried, afforded me the potential to achieve it.
Fackler and Roberts served in the military together. Both worked for years together at the Letterman Army Institute. IIRC, it was at LAI that Fackler was credited with developing the current 10% ballistic gelatin mix.
Fackler, Roberts, and Duncan MacPherson, all served on the IWBA board of directors ... with Fackler serving as President.
I'm well aware that companies like ATK do mobile ballistics testing ... and also have results posted on their sites. I was merely pointing out that some agencies/military operations still chose Dr. Roberts to perform the testing and sought his recommendations. In other words, while ammunition manufacturers are more than capable of conducting their own testing while meeting the protocol ... some folks still chose to utilize Dr. Roberts. IIRC, SOCOM enlisted Dr. Roberts help to both develope and test the 6.8mm rifle round.
In any event, the jest of my posts was that the IWBA/FBI protocol has indeed been one of the primary driving forces behind today's best ammunition.
Thanks for an excellent explanation.
As English's excellent post describes calibrated gelatin doesn't replicate living human flesh or tissue. It's an approximation of the consistency of soft human tissue that allows the medium to test a narrow window of data. With that in mind I'd hardly say those who make gel "don't care".
Bullet Test Tube makes no claims to replicating living human flesh or tissue but does state that their formula is consistent to the degree that a calculation can be made to compare with a bullet's penetration of gel.
I see no logic in accepting one artificial but consistent test medium while rejecting another artificial, consistent test medium.
I don't know how much of this thread you've followed, but I think a couple of posts bear repeating since it is such a long thread and good information can get lost in the depth of it.
Therefore I'm copy/pasting parts of post numbers: 376, 379, and 381. The main reason is to show you that more velocity alone doesn't neccessarily equate to more BPW. You may not care, but in case you're interested among possible others, the info is as follows.
The following are the current estimated probabilities of BPW playing a role for humans taking an unobstructed hit to the chest for given pressure wave magantudes:
500psi = 15%
700psi = 50%
1000psi = 75%
1300psi = 90%
The probability approaches 100% as BPW continues to increase, but will never really reach 100%. The accuracy in the prediction is roughly 10%.
The equation for JHP handgun bullets with 100% mass retention is -
p = (5*E)/(pi*d)
p is the peak pressure wave magnatude on the surphase of a 1" diameter cylinder centered on the wound channel (in psi). E is the impact energy (in ft-lbs) and d is the penetration depth (in feet).
If a JHP bullet fragments then generally whatever % the bullet fragments is the same % you need to add to the PBPW originally figured for nonfragmentation.
For FMJ handgun bullets the equation changes to a reasonable approximation of -
p = (3*E)/(pi*d)
For FMJ rifle bullets there is much more variation because some tumble deep and some tumble at shallow depths and some fragment. The retarding force profile (the more retarding force the greater the PBPW) is dominated by the depth at which a FMJ rifle bullet tumbles.
An FMJ rifle bullet which does not fragment and tumbles late in the penetration (10" or more) will have a peak pressure wave comparable to the formula for FMJ pistol bullets.
An FMJ rifle bullet which does not fragment and tumbles early (first 4") will have a peak pressure wave comparable to the formula for JHP handgun bullets.
If kinetic energy and penetration depth are equal, bullets that fragment create a larger pressure wave than bullets that retain 100% of their mass because the average penetration depth is shorter than the maximum penetration depth. Less penetration depth with equal kinetic energy = higher PBPW.
The following is why bullet fragmentation increases the level of peak ballistic pressure wave -
If kinetic energy and penetration depth are equal, bullets that fragment create a larger pressure wave than bullets that retain 100% of their mass. This is because the average penetration depth is shorter than the maximum penetration depth. Recall that the average force with no mass loss is given by [COC06c]
Fave = E/d,
where E is the kinetic energy and d is the maximum penetration depth.
If we consider the case of a bullet with some fraction, f, of mass lost to fragmentation, the fraction of retained mass is (1-f) and the average force is then given by
Fave = (1-f)E/d + f E/df,
where df is depth of the center of mass of the bullet fragments. In other words, df is the average penetration depth of the fragments. Most fragments do not penetrate as deeply as the maximum penetration depth d, so that the average fragment penetration depth df can be expressed as a fraction of the maximum penetration depth
df = d/k,
where k is greater than 1. Consequently, the average force becomes,
Fave = (1-f)E/d + f k E/d.
This can be rewritten as
Fave = [1 + f (k-1)]E/d.
So we see that the enhancement factor for the average force is [1 + f(k 1)], where f is the fraction of lost mass, and k describes the relative penetration depth of the mass lost by fragmentation. If the mass lost by fragmentation penetrates ½ of the maximum penetration depth on average, k = 2, and the enhancement factor for the average force is (1+f). In other words, a 40% loss of mass increases the average force (and thus the pressure wave) by 40%.
If the mass lost by fragmentation penetrates ⅓ of the maximum penetration depth on average, k = 3, and the enhancement factor for the average force is (1+2f). In other words, a 40% loss of mass increases the average force (and thus the pressure wave) by 80%.
Consequently, bullets that fragment can create larger pressure waves than bullets that do not fragment but have the same kinetic energy and penetration depth. Most fragmenting bullets have an average fragment penetration depth of ⅓ to ½ of their maximum penetration depth, so that the pressure wave enhancement factor is between (1+f) and (1+2f).
In other words, a bullet which loses 10% of its original mass has a BPW 10-20% larger than one which retains 100% of its original mass. Likewise , a bullet which loses 30% of its original mass to fragmentation has a BPW 30-60% larger than one which retains 100% of its original mass.
I have run the numbers for various common SD loads where I could get the pertinent apples to apples comparison data so we can see how different loads stack up against each other. The list is as follows -
The kinetic energy is listed after "KE", penetration depth is listed after "P" and is based on clothed gel for ALL rounds, expanded bullet diameter is listed after "E", wound volume is listed in cubic inches(ci) and is based on 12" penetration for ALL rounds unless a specific round couldn't manage 12" penetration, and in the last column in pounds per square inch(psi) is the peak ballistic pressure wave. Please note - for PBPW, for any round that fragmented to any extent, the PBPW is actually higher than what's shown. All PBPW numbers assume zero fragmentation. Very generally, for the PERCENTAGE a round fragments, that same percentage would be added to the PBPW in psi.
Most of the HST #s and Speer Gold Dot #s are based on averages from the ATK workshop results with various police departments. Those that aren't based on an average were tested only 1 time. Those workshop results can be viewed in their entirety here - http://www.le.atk.com/general/irl/woundballistics.aspx
Win 380auto T Series, 95gr, 1000fps, KE=211, P=7.95, E=.64, 2.6ci, 507psi
Speer 38special+P GD, 135gr, 860fps, KE=222, P=11.75, E=.59, 3.2ci, 361psi
Win 38spcl T Series+P, 130gr, 925fps, KE=247, P=12.00, E=.67, 4.2ci, 393psi
Win 9mm+P+ Ranger, 115gr, 1335fps, KE=455, P=8.50, E=.81, 4.4ci, 1023psi
DT 9mm+P Gold Dot, 115gr, 1415fps, KE=511, P=12.00, E=.70, 4.6ci, 813psi
DT 9mm+P Gold Dot, 124gr, 1310fps, KE=472, P=13.25, E=.70, 4.6ci, 684psi
Federal 9mm+P HST, 124gr, 1200fps, KE=396, P=12.50, E=.66, 4.1ci, 605psi
Federal 9mm HST,,,, 124gr, 1150fps, KE=364, P=13.90, E=.64, 3.9ci, 501psi
Win9mm+P T Series, 124gr, 1180fps, KE=383, P=13.90, E=.67, 4.2ci, 526psi
Win9mm +P Bonded, 124gr, 1180fps, KE=383, P=18.70, E=.54, 2.7ci, 392psi
Win9mm+P+TSeries, 127gr, 1250fps, KE=441, P=12.20, E=.68, 4.4ci, 691psi
DT 9mm+P Gold Dot, 147gr, 1125fps, KE=413, P=14.00, E=.66, 4.1ci, 563psi
Federal 9mm HST,,,, 147gr, 1000fps, KE=326, P=14.40, E=.66, 4.1ci, 433psi
Speer 9mm GD,,,,,,,, 147gr,, 990fps, KE=320, P=15.25, E=.58, 3.2ci, 401psi
Win 9mm T Series,,,, 147gr,, 990fps, KE=320, P=14.50, E=.66, 4.1ci, 422psi
Win 9mm Bonded,,,,, 147gr,, 995fps, KE=323, P=16.50, E=.59, 3.3ci, 374psi
DT 357SIG Gold Dot, 115gr, 1550fps, KE=613, P=12.12, E=.71, 4.8ci, 955psi
DT 357SIG Gold Dot, 125gr, 1450fps, KE=584, P=14.50, E=.66, 4.1ci, 770psi
Win357SIG T Series, 125gr, 1350fps, KE=506, P=12.10, E=.66, 4.1ci, 798psi
Win357SIG Bonded,, 125gr, 1350fps, KE=506, P=15.90, E=.57, 3.1ci, 608psi
DT 357SIG Gold Dot, 147gr, 1250fps, KE=510, P=14.75, E=.73, 5.0ci, 661psi
DT 357mag Gold Dot, 125gr, 1600fps, KE=710, P=12.75, E=.69, 4.5ci, 1063psi
Speer SB 357magGD, 125gr,,, 990fps, KE=294, P=14.50, E=.65, 4.0ci, 388psi
Win 357magSilvertip, 145gr, 1290fps,, KE=536, P=12.50, E=.59, 3.3ci, 819psi
DT 357mag Gold Dot, 158gr, 1400fps, KE=688, P=19.00, E=.56, 3.0ci, 692psi
DT 9X25 Gold Dot, 115gr, 1800fps, KE=827, P=10.00, E=.64, 3.2ci, 1579psi
DT 9X25 Gold Dot, 125gr, 1725fps, KE=826, P=15.00, E=.74, 5.2ci, 1051psi
DT 9X25 Gold Dot, 147gr, 1550fps, KE=784, P=17.50, E=.68, 4.4ci,, 856psi
DT 40S&W Nosler,,,, 135gr, 1375fps, KE=567, P=12.10, E=.72, 4.9ci, 894psi
DT 40S&W Gold Dot, 155gr, 1275fps, KE=559, P=13.00, E=.76, 5.4ci, 825psi
DT 40S&W Gold Dot, 165gr, 1200fps, KE=528, P=14.00, E=.70, 4.6ci, 721psi
Rem Golden Saber,,, 165gr, 1150fps, KE=485, P=14.00, E=.67, 4.2ci, 662psi
Federal 40S&W HST, 165gr, 1130fps, KE=468, P=14.00, E=.75, 5.3ci, 637psi
Win40S&W T Series, 165gr, 1140fps, KE=476, P=13.20, E=.70, 4.6ci, 690psi
Win 40S&W Bonded, 165gr, 1140fps, KE=476, P=19.00, E=.55, 2.9ci, 479psi
Speer 40S&W GD,,,, 180gr. 1025fps, KE=420, P=11.75, E=.72, 4.9ci, 683psi
DT 40S&W Gold Dot, 180gr, 1100fps, KE=484, P=14.75, E=.68, 4.4ci, 626psi
Federal 40S&W HST, 180gr, 1010fps, KE=408, P=13.40, E=.77, 5.6ci, 582psi
Rem JHP (not GS),,,, 180gr, 1015fps, KE=412, P=13.25, E=.69, 4.5ci, 594psi
Win40S&W T Series, 180gr,,, 990fps, KE=392, P=14.30, E=.70, 4.6ci, 524psi
Win 40S&W Bonded, 180gr,, 1070fps, KE=458, P=21.80, E=.51, 2.5ci, 402psi
DT 10mm Nosler,,,, 135gr, 1600fps, KE=767, P=11.00, E=.70, 4.2ci, 1332psi
DT 10mm Gold Dot, 155gr, 1475fps, KE=749, P=13.50, E=.88, 7.3ci, 1061psi
DT 10mm G. Saber, 165gr, 1425fps, KE=744, P=14.75, E=.82, 6.3ci, 964psi
DT 10mm Gold Dot, 165gr, 1400psi, KE=718, P=14.25, E=1.02, 9.8ci, 962psi
DT 10mm Gold Dot, 180gr, 1300fps, KE=675, P=15.25, E=.96, 8.7ci, 846psi
DT 10mm G. Saber, 180gr, 1330fps, KE=707, P=16.00, E=.85, 6.8ci, 844psi
DT 10mm Hor. XTP, 180gr, 1350fps, KE=728, P=17.25, E=.77, 5.6ci, 808psi
DT 10mm Hor. XTP, 200gr, 1250fps, KE=694, P=19.50, E=.72, 4.9ci, 680psi
Win 45GAP T Series, 230gr, 905fps, KE=418, P=12.70, E=.72, 4.9ci, 630psi
DT 45auto Gold Dot, 185gr, 1225fps, KE=616, P=12.75, E=.82, 6.3ci, 923psi
Rem45auto G Saber, 185gr, 1140fps, KE=534, P=14.25, E=.70, 4.6ci, 716psi
Win45auto Silvertip, 185gr, 1000fps, KE=411, P=13.25, E=.70, 4.6ci, 593psi
DT 45auto Gold Dot, 200gr, 1125fps, KE=562, P=14.25, E=.88, 7.3ci, 753psi
DT 45auto Gold Dot, 230gr, 1010fps, KE=521, P=15.25, E=.95, 8.5ci, 653psi
Federal45auto+P HST,230gr, 950fps, KE=461, P=14.60, E=.85, 6.8ci, 603psi
Federal 45auto HST, 230gr,, 890fps, KE=405, P=14.40, E=.86, 7.0ci, 537psi
Speer 45auto G Dot, 230gr,, 890fps, KE=405, P=13.50, E=.70, 4.6ci, 573psi
Rem45auto G Saber, 230gr,, 875fps, KE=391, P=14.00, E=.74, 5.2ci, 534psi
Win 45auto T Series, 230gr, 905fps, KE=418, P=12.70, E=.72, 4.9ci, 630psi
Win45auto+PTSeries, 230gr, 990fps, KE=500, P=15.20, E=.78, 5.7ci, 628psi
Win 45 auto Bonded, 230gr, 905fps, KE=418, P=15.80, E=.67, 4.2ci, 506psi
Bottom line, a number of different factors alone can increase or decrease the level of peak ballistic pressure wave. So if nothing else in the equation changes, the following by themselves will change the PBPW - penetration depth, velocity, kinetic energy, and bullet design/construction.
Here are some examples using the above data:
First lets take this load -
Federal 9mm+P HST, 124gr, 1200fps, KE=396, P=12.50, E=.66, 4.1ci, 605psi
We'll leave everything else the same but change the velocity to 1100fps. This change changes PBPW to 509psi.
Then this load -
Federal 40S&W HST, 180gr, 1010fps, KE=408, P=13.40, E=.77, 5.6ci, 582psi
We'll leave everything else the same but change the penetration depth to 12". This change changes PBPW to 650psi.
Those two examples should be enough to give you an idea of how not only can velocity change the PBPW, but how it and other factors alone can change it too.
I hope the above, if you cared to read through it, helps you understand more clearly where Dr. Courtney's theory is coming from.
Since I just reposted a lot of the info we talked about days ago, and you had mentioned going through/over some of the numbers yourself to see how you thought they panned out, did that ever happen, and if it did, did you arrive at any conclusions or form any new opinions or maybe think about things in ways you hadn't thought of before? Or didn't you get the chance to dig into it yet? I've been quite curious to hear your thoughts.
Craig, thanks for taking the time to share the info. Interesting.
It still seems in many cases, that the lighter/faster loads in each caliber often generate the highest PSI (BPW probability). I also realize that velocity is not the sole determinig factor regarding BPW ... which is why I mentioned (if necessary) in my previous post.
In 9mm for instance ... I would prefer to carry the 127gr.+P+ Ranger T vs. the 115gr.+P+ Ranger, even though the 115gr.+P+ load carries a higher potential for achieving BPW. Why? Well, I would get a good mix of lab performance (IWBA/FBI protocol), street performance, and a near 50% probablility of adding BPW as an additional wounding mechanism.
That's true. Most of the time in common SD loads the lighter/faster loads in each caliber will yeild the highest PSI. But it's not so much because the velocity is higher than that penetration depth will be less. It's all about the retarding forces on the bullet by the human/animal body.
The more energy you can stop quickest will give the highest PSI. Switch the bullet from JHP to FMJ, and PBPW drops off dramatically because of minimal retarding forces on the FMJ no matter how much kinetic energy it carries. Obviously a load must always be choosen that will reliably make it to the vitals, with BPW being looked at secondarily.
I just like to make sure. Way too many misconceptions floating around about Dr. Courtney's theory out there!
Your welcome. Never hurts to know more than less.
I think after talking to enough people with experience in the field and seeing a few gunshots (on video admittedly) I'm pretty convinced the part about a pressure wave killing instantly by "shocking" the brain or what not is indeed a myth, especially at handgun velocities.
However, I'm also nearly convinced that a bigger secondary cavity caused from the pressure wave can in some cases cause enough additional trauma to speed incapacitation. I've seen a video of a 30-06 rifle not only explode the ballistics gel into smithereens, but it also broke the table in half!
Borris once told me he didn't trust 115grain +p ammo, because he'd had problems with it reaching the CNS on some larger animals, yet at the same time he noted it had some very impressive entrance wounds. And that tells me the entire story right there... you simply MUST have good penetration, but if you can find a bullet that can give you both good penetration and explosive cavity wounds, go for it! That's why I think .357 does so well. It gets the penetration needed but has that extra edge of velocity to tear #$IT up on it's way in.
Just my humble opinion.