9mm vs. .45 - but different!

[coltoriginal]

saturno_v

The real world doesn't happen in a vacuum...

This is true. Therefore vacuum's are not relevant in anyway to this example.. what are you trying to prove here? the practical application of both as described encompasses wind resistance and the computations are "rough" as i originally said. For that matter, the bullet weights and velocities from the chrono #'s posted also did not happen in a vacuum and therefore the numbers and those derived from them are perfectly accurate and accountable.. again no vacuums anywhere. unless you think there is significantly more wind resistance in one state vs another lets just assume air is all the same

yes a 45 will meet more wind resistance than a 9mm because of larger cross-section.. if thats what you are trying to say it doesn't matter anyway because we are comparing 45 to 9mm.. its already included in practical application (i have never seen a shooting range in a vacuum). my numbers are not real world accurate to the .0001 because of the unknown range at which rounds were chrono'd. but who cares? variables between ammo in the same box would still have more effect

tap that rubber block with a given hammer and measure its movement...then whack him harder with the same hammer...the hitting mass did not change...you increased both momentum and, even more the KE.

please explain what you are trying to say there.. it seems you just greatly overcomplicated an explanation of how you can hit something harder with a hammer. no need to say blue is blue or harder is harder
fyi KE=Momentum=Inertia and at point of impact =Force (see po-tay-to vs po-tah-to for clarification)

Hydrostatic shock has never been proven....you can read some literature by Dr. Martin Fackler, FBI studies and others....

anyone who has shot anything remotely fluid (i.e. soft clay, water jugs ...) with a high powered rifle knows the effects. Shoot a squirrel with a magnum hunting rifle and i guarantee you 90% of the little guy will literally disappear from that tiny little bullet, while the round itself will pass clean through. what else do you call that?

You do raise a good point however about elastic vs inelastic transference and the dissipated energy due to penetration, However that is one of the minor variables i alluded to in my first post (such as overcoming static friction) that were unknowns.

 

[GLOOB]

Gloob

With the same impact energy a bullet with smaller frontal area all else being equal (SD, shape, construction, etc...) will penetrate better....a larger bullet will create a larger wound channel...they will expend their energy in a slightly different way.

The smaller bullet will actually be more "efficient" because of the "easier" penetration...but as we know, overpenetration can be a disadvantage (dangerous and wasted energy outside of the intended target).

So it all depends...if you want the largest wound channel the larger bullet will serve you better...if you want maximum penetration the smaller bullet will do it....

Well, yes and no. Given the same diameter, a 230 grain 9mm bullet with equal kinetic energy to a 115 grain 9mm bullet going 1200 fps might actually penetrate deeper. But that's not my point. My point is that the faster bullet causes more cavitation and heat... meaning it is not as efficient in its transformation of kinetic energy into work on impact. Unless the target is a pidgeon. In this case, cavitation might cause a meat and feather explosion.

 

[saturno_v]

Coltoriginal


My point is very simple....the 45 ACP has more momentum than the 9 mm but that additional momentum will have neglibible effects on the penetration and stopping power abilities...there are several other factors taking precedence...


When you shoot a squirrel with an extremely high velocity bullet, the red mist effects is often generated by the bullet exploding or tumbling...

However, limited hydrostatic effects can be noted the the area next to the bullet path....what it means is that when a squirrel get hit by a 30-06 round is like one of us getting hit by a 16 inches Mark 7 naval gun shell....so even limited hydrostatic effects close to the bullet path it will encompass much of the squirrel body...even simple tissue displacement and cavitation generated by the passage of the bullet will be in a considerable amount compared to the whole target mass....enough the generate a blow up without being an hydrostatic phenomena....you get the picture....

By the way you can red mist a squirrel even with a 45 or a 9 (witnessed personally)....you do not need some mythical Roy Weatherby velocities....

One little rodent was red misted by a friend of mine firing an Aguila 22 LR HP Interceptor...

Larger bodies will not show almost any meaningful hydrostatic damage with regular rifle bullets.

The soft clay going everywhere is simple medium displacement.....even the softest living tissue is sturdier and more stuctured than that (blood vessels, nerves, etc...)

 

[kyo]

F(force)=M(mass) xA(acceleration)
You do this with both bullet types. You can use the velocity provided by the companies for each bullet. This gives you the acceleration out of the muzzle. Done.
Now, for example we have from the same reload manual
F=147g(Hornady Xtp 9mm) x 1004 f/s(velocity of this round)
=147588(not sure what unit this would be at...sorry)

Then we have
F=230g(Hornady FMJ FP) x 908 f/s
=208840

The 230g is over 1.5 times the weight of the 147g. The velocity of the 9 is only 1.1 times the velocity of the 45.

Take the weight in grains of the block, or transfer from grains to grams for the bullets, and then do a transfer of energy look at it. This would be vector of the bullet Vs vector of the block. The block is standing still. So, the bullet transfers its kinetic energy or force to the block. The heavier bullet will transfer more force because it is heavier, and only travels less than 100 f/s slower.
I pick the 45. Thats why I have one
If you don't believe in hydrostatic shock, look at this guy's hand...
http://www.thegunzone.com/nd.html

 

[coltoriginal]

My point is very simple....the 45 ACP has more momentum than the 9 mm but that additional momentum will have neglibible effects of the penetration and stopping power abilities...there are several other factors taking precedence...

agreed.

When you shoot a squirrel with an extremely high velocity bullet, the red mist effects is often generated by the bullet exploding or tumbling...

disagree.

However, limited hydrostatic effects can be noted the the area next to the bullet path

first you say theres no such thing, now you say there is...

However, limited hydrostatic effects can be noted the the area next to the bullet path....what it means is that when a squirrel get hit by a 30-06 round is like one of us getting hit by a 16 inches Mark 7 naval gun shell....so even limited hydrostatic effects close to the bullet path it will encompass much of the squirrel body...even simple tissue displacement and cavitation generated by the passage of the bullet will be in a considerable amount compared to the whole target mass....enough the generate a blow up without being an hydrostatic phenomena....you get the picture....

i dont like this comparison because it is ridiculously scaled up. But, since you will agree to nothing less than a Mark7 naval shell having hydrostatic shock, compare that to the much slower black powder cannonball (comparable in mass but no hydrostatic shock because no speed.. granted they will still take limbs off, they are however just hole punchers similar to 45 and 9mm the damage comes from direct contact with the ball itself)

By the way you can red mist a squirrel even with a 45 or a 9 (witnessed personally)....you do not need some mythical Roy Weatherby velocities....

by red misted do you just mean spatter? i'm talking about making it disappear... like david copperfield

Larger bodies will not show almost any meaningful hydrostatic damage with regular rifle bullets.

strongly disagree

The soft clay going everywhere is simple medium displacement.....even the softest living tissue is sturdier and more stuctured than that (blood vessels, nerves, etc...)

strongly disagree, fluids do not compress and humans/animals are atleast 60% water. that rapid displacement will be violent and torn tissue will ensue

i'm done with this debate, to each his own

 

[saturno_v]

Coltoriginal

If you read my previous posts, I always said, mentioning a reference, that VERY limited and weak hydrostatic effects can be observed in tissues immediately adjacent the bullet path.....but they are negligible when it comes to effectiveness and stopping power.

I witnessed .223 bullets exploding on a blade of grass...literally....


Things don't vanish a' la David Copperfield ....it will be blown up in pieces and partially pulverized....yes I saw that on a rabbit hit by a 357...red mist indeed...


Yes our bodies are made of 60-70% water...however contained in relatively strong and elastic tissue reticulum capable of resisting any negligible hydrostatic effects a small bullet may create...different than soft clay...

King Ghidora

The surface area of the butt of the rifle keeps it from being the lethal weapon that the bullet is. The same amount of energy is dissipated through the butt of the rifle or the handle of a handgun unless some of the energy is directed elsewhere but in either case the amount of energy equal to the amount applied to the bullet is spent somewhere in the gun and the size of the area where the energy is dissipated is what keeps it from being lethal.

The reason the larger area isn't lethal is that it exceeds the amount of energy per square inch that is needed to penetrate the body of an animal or a human. It's no different than the bottom of a boat. If you drop an iron rod straight down into a river it's going to break the plane of surface tension of the water and sink. If you spread that same amount of iron out to a flat surface with a side design to prevent water from flowing on top of the iron then it will float. The iron rod is the bullet. The flat iron is the butt of a gun.

I could not agree more...very well put


On the rest I agree up to a point...yes the 45 will generate a wider wound channel but it will penetrate less, on average, because the wider bullet, assuming the same energy, will experience more drag.

The difference in the wound channel diameter between a 45 and a 9 (assuming no expansion) is going to be negligible, when you consider the size of a human body, in order to make a difference in effectiveness, shot placement is BY FAR the more important factor....

Again, assuming the same energy and bullet construction, the 45 will spend its energy generating a wider wound channel, the 9 will penetrate more.....I do not think one situation is always better than the other.....ergo I would not say one round is more effective than the other....

To paraphrase your recoil explanation (buttplace and needle)....when you fire a 338 Win Mag, one one side the shooter may experience just a bruised shoulder, on the other side a very small bullet with that energy concentrated in such small area, will travel through a Moose lenghtwise!!!

I'm done too...it's late and I'm going to bed..

Regards

 

[kyo]

yea if you are testing round nose, fine. Even with round nose, a 9mm is far more likely to pass through a person and NOT dump all of its energy into that person. A 45 being slower and heavier, will have a better chance. Now, if we get into hollow points the 45 also has the advantage because it can expand to a nice diameter. examples in the link
http://books.google.com/books?id=Dk...=X&oi=book_result&ct=result&resnum=8#PPA76,M1

Page 76 is the chart. 1.75 times the original diameter. So, a 9mm would have to expand perfectly to get to 1.75 to have the same diameter as a 45 with 1.5 times expansion.
sleepy time too...long day

 

[lvcat2004]

I've read the post with great interest, and would like to comment. I believe that shot placement is of utmost importance and the caliber is less relevant, but here are my thoughts on caliber comparisons.

I disagree with some of the comments by King Ghidora as your analogy about water, pool, hammer, needles are all irrelevant as we are talking about things moving at much faster speeds, as well as skin being covered by clothes, other materials AND with deforming projectile such that physics is much too complicated to be put into such simple, and most importantly, irrelevant analogies.

If I were you, I wouldn't bring up your PhD STUDENT son to this argument. A student is NEVER a foremost expert in the field in anything. I've had my doctorate for years--you can trust me on this.

WWII/Vietnam war anecdotes are equally useless in that bullets used in wars are not comparable to modern JHP that we would use to shoot BG's.

There were a lot of 7th grade physics formulas thrown around earlier, but I belive that such simplistic explanations obvioulsy don't clear up the picture, since theare are far more variables and complex and dynamic interactions that get involved, not mention physiologic effect on the LIVE target that occurs as a result that bickering about 7th grade physics is not productive in advancing our understanding of this process.

I conclude that in modern bullets/ammos, there are not significant performance difference among 9/40/45ACP and such. That exactly is the reason that we keep on seeing these 9 vs 40 vs 45 threads without any conclusive scientific evidence. Someone who changes his mind from his one shot of buffalo oviously does not believe in scientific principles, but my thought is that this dynamic interaction of bullet penetrating clothes, skin, then expanding and damaging vital organs, in context of velocity, bullet weight, AND the resulting physiologic effect is not easily predicted by scientific models, but at the same time we canot conduct a double blinded randomized prospective study to compare the effectiveness of each caliber/ammo in live subjects to a point where we can come up with reliable scientific conclusion.

There is no winner/loser in this argument, and agreeing/diasgreeing with parts of each others comment will get us nowhere.

I stand by using what is most comfortable to shoot, with the most reliable weapon. I do believe however, that having more ammos is better than having less. I'd prefer to have 2 wound channels to 1.

Back to OP---shooting rubber blocks is utterly useless. I bet if you had shot with 223 or 308 you would have been the slowest person moving the block. Does that mean you wouldn't want to shoot a 223 or 308 against a BG??

 

[Tropical Buzz]

Bigger is better, bigger is better, squaaaawk!

The facts that some are choosing to ignore:

YES a .45 is bigger than a 9mm - BUT by only 1/10 of a square inch!!

YES A .45 @ 230gr is heavier than a 147gr 9mm - BUT by only 83gr!!

The average human target weighs in the region of 175lbs.

83gr = 0.012lbs.

230gr =0.033lbs

175lbs = 1225490.1grains!!!

While the weight/size difference may mean something to a 1lb squirrel or a rubber block, compared to the size and weight of a human body the difference in weight between the two rounds is laughably negligible!

The difference in size of the wound channels is also insignificantly small!!

If you miss a vital target by 1/10 of an inch with the 9mm, you would still miss if you had used a .45!

YES the hammer/needle analogy is a ridiculous exaggeration in this context. Use a blunt ice pick vs. a sharp ice pick instead.

THE DIFFERENCE IN "SIZE" BETWEEN A .45 AND A 9MM BULLET IS INSIGNIFICANT IN A HUMAN SIZED TARGET.

With good modern ammo, both can penetrate vital areas with equal proficiency. Where you place the shot is all that's going to matter.

The strength of the pet preconceptions we cling to has way more stopping power than any handgun round!

Re: hydrostatic shock, no handgun round hits hard enough to send a shockwave pulse through your blood vessles that will destroy your heart valves and disrupt your brain.

 

[chieftain]

Simply amazing.

I reference the leading scientific researcher on the topic at hand, and many of you, very smart folks, a lot smarter than me, ignore him and start your own "theories" of applied Physics and how YOU THINK IT APPLIES OR SHOULD APPLY to terminal ballistics.

Guys, I am reading and hearing way to much denial in this thread. Rationalizations to justify your arguments are specious at best. The expert on the subject states "Basically all the standard service calibers work when fed good quality ammunition".

How many folks here don't understand this research? Go to M4carbine.net and read the terminal Ballistics information. Read test results that matter, and have already shown their validity and accuracy.

Read the existing research. Use it. Now that is radical.

Go figure.

Fred

 

[DRYHUMOR]

Energy, mass, velocity aside.

Point of aim must also be considered. The "sectional density" of the target will have a variable effect to either caliber.

 

[Davionmaximus]

You just wait... some special intrest group is going to start marching on Washington claiming the 2nd amendment group is abusing rubber blocks... I can just see it now!!

 

[wickedsprint]

This same argument has roots in a blade discussion. A 9mm is basically just a sharper knife. You stick someone with a sharp knife, the blade goes in, they may not even react or move. You stick em with a butter knife, especially one going slower..they might get pushed back before blade does anything and they'll certainly notice. There is your momentum theory. It's all about PSI. Me, I'll take the sharp knife. The .45 has already demonstrated poor penetration abilities in certain mediums, hence why they came out with the .38 Super..which shares surprisingly similar ballistics with a hot 9mm.

 

[CDW4ME]

Great thread

Good post have been made already about momentum, elasticity, hydrostatic shock.....I've got my own copies of Handgun Stopping Power, Street Stoppers, and Stopping Power so I've read the 1 shot stop theories too.

I'll add some chrono results, this "apples to apples" as much as is possible.

Kahr PM9: Remington 115+P @ 1098 fps. 307 # KE or .56 momentum
Kakr PM45: Remington 185 @ 889 fps. 324 # KE or .73 momentum

KE and momentum are both measures of penetration potential. Projectiles with higher momentum are more resistant to deflection. Archers can blow through a deer with very low levels of KE (about 60# KE) due to the comparitively higher level of momentum (around .50). Higher KE is more likely to create hydrostatic shock.

The 45 carries two less rounds, but I prefer the larger bullet; if I'm carrying the 45, I can't wish I carried something bigger. I'll carry the PM45 over the PM9 anytime I can conceal it.

 

[RedLion]

hmmmmm, I'm pretty sure some of the physics in this forum are a little screwed up, but what the hell would I know right???

bullets in real life=Momentum, Bullets in Marketing world = kinetic energy. Very different things, although related.

Surface tension- properties of a liquid
human skin/flesh/bone-solid-so no surface tension right?


deflection- caused by force directed in different direction other than what object is traveling at, only dependent on Mass and Acceleration, not only Velocity of object.

So if a blade of grass applies a force to the bullet in another direction other than the one its traveling in, its is the same as the wind applying a smaller force over a longer period of time. IE all bullets get deflected by grass/wind/whatever you want, the amount is dependent on the momentum of the bullet. Granted the blade of grass doesn't change the orientation of the bullet.

Shooting Blocks/Sheet Rock=/= shooting people. You PHDs in ballistics/fluid dynamics/human anatomy/supersonic objects should at least know that ceramics/rubbers/composites are very different and will act accordingly when hit by metallic bullets at speed. The only reliable way to see how a bullet is going to act when it hits a person is by shooting a person, or materials that mimic people very closely. Otherwise your 'hydrostatic tensions' don't apply very well in rubbers or ceramics, I hope you didn't use these findings of penetration on the internet in your theses, because they are not based in science, no matter how closely they mimic what we find in the real world.

Terminal ballistics is a very sketchy science. There are simply too many variables to take into account, which is why we test everything, and there is no FEA for bullets.

I still fail to see why a person with a PHD working for NASA would waste their time talking to us idiots on a firearms forum, and try to explain there extensive Air Force funded research into the .45 ACP to us. Maybe this war has gone on long enough?

Plus the reason you get a PHD is because you did research and became an expert in you field. And by field I mean something extremely narrow, like measuring atom structure of crystals by hitting them with x rays, not just fluids or something like that. So don't get too angry you guys, I'm sure the DOD is paying you ten times what we can ever hope to make.

 

[ArmedBear]

there are several other factors taking precedence...

Sure. Penetration is equal, and deflection is less with the .45 (therefore it's more likely to break bones, or keep going through heavy fabric or leather, than be deflected by them). But let's pretend that the two will follow about the same track in the target, because that's what the ballistic gel looks like. If anything, this gives the benefit of the doubt to the 9mm anyway.

And since you deny that there is really such thing as hydrostatic shock (and so do I at the velocities in question), let's not imagine that hydrostatic shock isn't a factor. We agree on that anyway.

Then, the primary remaining factor is the size of the bullet, once expanded.

Let's assume that we're using the same bullet design in each caliber, because anything else is apples-to-oranges anyway.

So you're claiming that an expanded 9mm bullet going 13" deep will cause equal or greater damage to the target than an expanded .45ACP bullet does, traveling that same 13"?

Sorry, but that's nothing short of ridiculous.

 

[weisse52]

I just like the .45 better. So that settles it for me.

Ok, you guys can get back to your discussion.

 

[Woodrowmag]

It only makes sense that a bigger projectile would move an object (that is light enough to be moved by said projectile) more than a smaller one. Shouldn't really come as a surprise.

A human being is generally a lot heavier than a little rubber block. A human being is also a large enough target where a millimeter here and there won't make a difference. The shot that kills you with a .45 auto will also kill you with a 9mm.

If given the choice to get shot by either round, I'd say, 'shoot me with either. If I live, I probably won't notice the difference.' In the end, these discussions are silly, especially to get your panties in a knot over.

 

[blkbrd666]

I have a .45 vs 9mm story. When I was in college, a friend of mine came over to go shooting. I lived out in the country so we were just shooting at cans, boxes, etc. in the back yard. I stood a car muffler up on its end for us to shoot at and drew about a 4" black dot/circle on it for a target. We backed off and I shot first with a Walther P38 9mm. I emptied the mag, 8 shots, and the muffler never moved. My buddy pulled out his 1911 and fired one shot and sent the muffler flipping end over end about 10-15 feet away. As we were walking down to look at the muffler, he was laughing hysterically and commented, "I can't believe you missed 8 times!". When we got to the muffler it had 8 holes in the big black dot and all exiting out the back. There was one big dent in the muffler just above the dot about the size of a fist and an inch deep. We backed up to where the muffler had been standing and his flattened .45 bullet was laying there on the ground. Completely different results from the 2 calibers, but pretty interesting. He quit laughing.

 

[KBintheSLC]

The narrower 9 mm plows through easily while the 45 meets more resistance so the block moves....momentum has absolutely NOTHING to do with it

Saturno...

I think you are sort of right, but momentum still plays a major role. The greater momentum of the heavier bullet is fully absorbed by the object due to the bullets greater resistance aka profile. This may result in less penetration for the heavier, wider bullet. But, we don't know that the lighter 9mm did not remain inside the block as well. If all bullets failed to exit the block, then momentum is king as we can assume that all momentum was transfered to the block.

So don't bang your head too hard over it.

Yes the beloved standard 45 round has more momentum than a 9 mm standard round, I give you that.....does that means that a 45 is more effective than a 9 just because of momentum....definitely not

If you think that I was implying such a thing when I made my statement on momentum, you are profoundly confused, and obviously failed to read the rest of the post. It was simply a response to the rubber block scenario. No need to get sensitive.

..

 

[DRYHUMOR]

When you pratice head shots...

it makes no difference.

 

[lvcat2004]

Chiftain: I agree with you completely that the software is more important than a caliber argument. You must be able to hit the target first, multiple times before we even start talking about this stuff in the first place.

I missed your link to Dr. Roberts results however, it's not the ballistic gel stuff is it?? I would like to take a look if you don't mind giving me a link to it. I personally think that ballistic gel result is just ONE component of this big puzzle and inadequate to make any conclusion as to what is more effective on a LIVE, CLOTHED target with heterogenous densities, unlike that of ballistic gels.

However, I would be hard pressed to look at just one expert opinion and calling it a day. There are many subjects in which many "experts" can't agree on, despite "evidence" they claim to have. Some studies are more well designed than others, and you can deduce different conclusions based on the study design and execution. I don't think that we have a conclusive scientific evidence on this matter.

King Ghidora: I have no hostility to you and I never said that surface tension is completley irrelevant. I implied that your one-minded argument as if surface tension explains everything is irrelevant. Besides we're really not talking about shooting bullets into water, but solid substances, clothes, skin, tissues, bones, with deforming bullets. It's a particularly poor analogy.

My Doctorate is in Medicine. I have published articles as an undergraduate and as a graduate, post-graduate...those of us coming from top schools all do that, sorry to burst your bubbles. I understand that you are a proud parent, and a former engineering student, but my undergraduate work was done in biochemistry where the department is #1 in the nation, as well as having physics, mechanical engineering, chemical engineering, EECS graduate schools all top 5 in the nation (according to US news and world report, whatever that's worth). Does that make me more credible since you boast about your "leading" school career?? GRE score?? My goodness, I can talk about my SAT, MCAT, USMLE scores and percentiles, but those of us professionals that have been in the business for over a decade don't really talke about tests for "students"

I know MANY post-docs, graduate students, and there were more Nobel Laureates in my school than any other school in the WORLD. I know what it takes to be the "expert in the WORLD", and I can assure you that your graduate student son is NOT it. Simply writing a PhD thesis on a narrow subject doesn't qualify your as a "world expert" Let's take your poor son out of this thread....now I can't remember why you brought him in this mess in the first place. What does OUR eductaion or our kids education matter anyway in this matter??

Redlion: Thanks, exactly my point. This problem is too complicated to be solved by simple formulas.

I can say one thing though....if you think this can be explained by a single physics principle or one newtonian formula.....you probably don't get it. I'm sorry Dr. surface tension.

 

[chieftain]

Chiftain: I agree with you completely that the software is more important than a caliber argument. You must be able to hit the target first, multiple times before we even start talking about this stuff in the first place.

I missed your link to Dr. Roberts results however, it's not the ballistic gel stuff is it?? I would like to take a look if you don't mind giving me a link to it. I personally think that ballistic gel result is just ONE component of this big puzzle and inadequate to make any conclusion as to what is more effective on a LIVE, CLOTHED target with heterogenous densities, unlike that of ballistic gels.

Thanks Doc. The link is back in my Post #22 of this thread. Once you get to Doc Roberts data on M4Carbine Net, you will be able to link to a lot more data and references in regards to this subject.

I am impressed by all the credentials you folks have though. I got a 4 year full ride scholarship to USMC, and did my graduate work in Vietnam for a couple of years plus. The extra curricular stuff was special though.

I used to ask a few of questions to those who would always insist on any given caliber over another: In this case using the classic 9mm vs 45acp. Replace any of the traditional fighting handgun calibers here.

If I place three 9mm bullets exactly where they need to be in the BG, what do you think will happen differently if I place three 45acp bullets in the exact same place?

NOW

If I place my three 9mm bullets in a non critical area of the bad guy, what do you think will happen DIFFERENTLY if I place three 45 bullets in the exact same place?

Can I get an "AMEN" from all the high priced help we have here?

That is about all I have to add to this argument at this time.

Go figure.

Fred

 

[Tropical Buzz]

Sure. Penetration is equal, and deflection is less with the .45 (therefore it's more likely to break bones, or keep going through heavy fabric or leather, than be deflected by them). But let's pretend that the two will follow about the same track in the target, because that's what the ballistic gel looks like. If anything, this gives the benefit of the doubt to the 9mm anyway.

And since you deny that there is really such thing as hydrostatic shock (and so do I at the velocities in question), let's not imagine that hydrostatic shock isn't a factor. We agree on that anyway.

Then, the primary remaining factor is the size of the bullet, once expanded.

Let's assume that we're using the same bullet design in each caliber, because anything else is apples-to-oranges anyway.

So you're claiming that an expanded 9mm bullet going 13" deep will cause equal or greater damage to the target than an expanded .45ACP bullet does, traveling that same 13"?

Sorry, but that's nothing short of ridiculous.

In the interest of furthering a spirited but civil and interesting debate, here is a comparison of of two good rounds in their respective calibers vs. a machete weilding block of ballistic gelatin bent on murder and mayhem. (compliments of Brassfetcher).

.45 Hornady 230gr XTP
Velocity 881 fps
Best penetration 12.7"
Expanded diameter .736"
Wound channel volume* 5.4 cubic inches

9mm Remington 147gr Golden Saber
Velocity 959 fps
Best penetration 14.5"
Expanded diameter .627"
Wound channel volume* 4.5 cubic inches

The 45 hole is less than 1 cubic inch bigger than the 9mm hole. Not really very significant in terms of blood loss or tissue damage. Exactly what part of the body these holes are made in and not the size of the holes will determine the lethality of the hits.

*ASSumes that the bullets reached full expansion size on impact. A linear expansion model would produce essentially the same results.

A few observations based on some of the other posts:

1. A bullet skipping off the water has nothing at all to do with surface tension. It skips because water is non-compressible and behaves like a solid when impact occurs too fast to allow an equivalent volume to be displaced.

2. Most of the calculations and scientific data presented in various posts is correct. They establish and support what we already know; ie: a larger, heavier object pushed to an equivalent velocity will have more (potential) kinetic energy at impact. What's being consistently overlooked is the insignificance of the delta in relation to a target that has thousands of times more mass than either of the bullets.

3. The issue of recoil is a relevant point of discussion. The theory of equal and opposite reactions dictates that a gun should recoil with the same energy as that of the bullet leaving the barrel. It does. But there is more to consider than just the surface area of the buttstock when explaining why the shooter doesn't get his shoulder or hand blown off. For one, the gun has way more mass than the relatively tiny bullet and is moved far slower and a way smaller distance than the bullet. In auto loading guns, the recoiling bolt or slide/spring assembly, which also have many times more mass than the bullet, absorb much of the "equal and opposite reaction". This is why a lightweight snubby kicks harder than a 6" steel revolver firing the same round.
To get a feel for the importance of mass when discussing the practical conversion of energy into work, fire a ball bearing out of your kid's slingshot, then try using the same sling and rubber bands to launch a 5 pound rock.

 

[wickedsprint]

Thermometers also have degrees and we know where they stick them...

That being said, I'll take the 9mm for the extra capacity and cheaper ammo. Why is it always 9mm vs 45 anyways? You can buy some pretty compact 357 Magnums that are much hotter than both.