9mm vs. 45!
I shudder to think how many times this topic has been discussed not only on the Internet, but also in gun shops and printed text. No doubt that many trees have been felled to provide the paper for the latter and the question persists. We do see the same sorts of discussions on the 9mm vs. other popular calibers, but I still believe that the war between 45 and 9mm rages the hottest. Intelligent arguments for both sides have been provided, but often times, the answers really shine…in their stupidity.
Let's take a look at some that might seem to make sense but in fact imply certain things that are just not true.
"The .45 is best. Would you rather get hit by a bowling ball or a golf ball?" This little gem or something very near is frequently used to give the inquiring soul "guidance" in his decision on 9mm vs. 45. First, nothing is said about velocity. One is left to assume that both of the balls are traveling at the same speed. Such is not the case when comparing 9mm and .45 ACP. Secondly, the difference in diameters is a bit exaggerated. The differences in the balls' diameters are considerably greater than the .356" vs. .452" 9mm and .45 diameters.
"The 9mm is best. With modern loads it is potent and holds a lot of shots. I feel more secure with 15 shots than seven to nine in the larger caliber." I do believe that today's crop of 9mm defensive ammo is very good and very possibly we are seeing the best loads that can be had, not only in 9mm but in other calibers as well. The "best" part sort of messes things up for me. The 9mm may very well be potent (and I believe that it is), but does that prove "better" (than .45 ACP), which is almost always the question really being asked? The "feeling more secure" part is dependent upon the scenario envisioned by the user and personal preferences. IF one runs into the usual 3 or 4 shot deadly force scenario, but cannot "solve" the problem quickly against deadly opponents, he will possibly run out of time before ammunition. While some 9mm's large magazine capacity might very well be useful in some situations, it doesn't necessarily guarantee success across the board.
The .45 ACP may very well be the more potent than 9mm, but some responses seem to convey the notion that the 45 is akin to a deathblow without fail and that the 9mm might be effective only on injured sparrows…and then only with repeat shots! One of my personal favorites is that the 9mm was "designed to wound" while the 45 ACP was "designed to kill." Anyone even vaguely familiar with the history of Georg
Luger's development of the round knows which the 9mm's parent round and to discard the "design" comments in the nearest trash container.
Let's take an unemotional look at these cartridges as well as some actual velocities and expansion characteristics and see how much of the elusive truth we can find.
Discussion on the merits of most handgun calibers/loads for self-defense is frequent. Here we see a .357 magnum 145-gr. Silvertip, .357 magnum 125-gr. Corbon DPX, 38 Special Remington 158-gr. LSWCHP +P, Remington .45 ACP 230-gr. Golden Saber and its 9mm counterpart. This article will focus only on the never-ending 9mm vs. 45 debate.
In normal trim, the .45 ACP averages about 830 ft/sec with most FMJ 230-gr. bullets when fired from a 5" barrel. The 9 x 19mm cranks out a 115-gr. FMJ at about 1140 ft/sec from many service length barrels which range from 4 to 5". If a 124-gr. FMJ is being used, these same pistols will usually get between 1080 and 1120 ft/sec in standard pressure cartridges. (These figures are ballpark accurate and based on chronograph results from lots of rounds from different pistols. Not all barrels of the same length provide identical velocities and not all 45 or 9mm pistols have the same length barrels. Figures given represent close general velocities from service style pistols.)
We see then that the 230-gr. traditional load moves at about 73% the velocity of the traditional 115-gr. 9mm round. We can approximate by saying this in another way: This common 45 load has approximately 3/4 of the 9mm's velocity but with twice the bullet weight…and about 60% greater frontal area.
Let's take a gander at some other loads for both calibers and see how they stack up against each other.
Speer's excellent 9mm 124-gr. Gold Dot (std. pressure) chronographs 1109 ft/sec on the nose from one of my Mk III Hi Powers. The same company's standard pressure .45 ACP 230-gr. Gold Dot averaged 856 ft/sec fired from a 5" STI Trojan. Both of these bullets will normally expand in tissue due to very good engineering and design and fragmentation is practically non-existent. (I am not necessarily saying that fragmentation is bad, but only that it is a variable that has been removed in this bullet comparison. FWIW, the +P version of the 9mm load hits 1200 ft/sec on the nose from the same Hi Power, but let's look at standard pressure loads to keep it "apples to apples.") In this case, the twice-as-heavy .45 bullet has 77% of the 9mm's velocity, still in that 3/4-comparison ballpark.
When both of these rounds are fired into calibrated 10% ballistic gelatin, now considered the gold standard for expansion/penetration testing, the following results are usually the norm when 4" 9mm pistols are compared to 5" 45's.
The 124-gr. Speer 9mm Gold Dot averages about 13" penetration and expands to approximately .57".
The 230-gr. 45 ACP Gold Dot averages approximately 13.5 - 14" and expands to right at .70".
Because of its higher velocity, the recovered 9mm Gold Dot bullet's final expanded diameter is often slightly smaller than at some point in its expansion because the expanded bullet folds rearward more than the slower .45 ACP.
Using these real world figures, let's take a closer look.
The expanded 9mm 124-gr. Gold's frontal area measures approximately 0.25 sq. inches compared to the .45's frontal expanded area of .38 sq. inches. So while the expanded diameter of the 9mm is about 81% that of the larger caliber's, the resulting frontal area of the 9mm is 66% that of the 45's. I don't find these results surprising. Remember, the same company made both bullets and this design is considered one of the best currently available. The .45 ACP unexpanded frontal area started off 60% greater than the 9mm's. The 9mm would have to expand quite a lot more proportionally compared to the .45 to wind up with the same diameter. The problem is that in normal trim, the bullet would be very much like a pancake in shape and might very well not hit the 12" minimum penetration depths considered essential by many.
(This emphatically does not mean that we can expect to see .57" or .70" holes in "soft targets" hit by these loads. Tissue tends to collapse back together after the bullet passes through it, but it does strongly suggest that the permanent wound track from the .45 will be larger than that of the 9mm. It follows that if these bullets struck similar areas such that copious bleeding resulted, there is probably an advantage to the larger caliber. On the other hand, if a major vessel was severed by either, internal bleeding might very well be the same. If the nature of the wound was such that blood loss was primarily through the permanent cavity, it seems logical that the larger one would be more efficient.)
The example I just cited is based upon actual chronograph results as well as ballistic expansion data from several sources and the use of simple mathematics. Those wishing to do so can easily crank out the results for other load comparisons in these two calibers. I'll move on to other aspects in this seemingly endless caliber "war."
All moving objects possess two physical quantities. They are momentum and kinetic energy. Some folks say that momentum plays an important role in "stopping power" while others favor kinetic energy. Still others insist that neither play any significant role in making bad guys drop when smacked with a pistol bullet. This same group almost always opines that the only relevant measurement in "stopping power" is the permanent cavity. It's depth and diameter is all that counts according to them. I wonder if this is really true and while we're on the topic, let's take a look at momentum.
Momentum is simply the bullet's mass multiplied by its velocity. Mass is not the same thing as weight, although for our purposes it can be thought of as such. Mass can be thought of as how much matter an object possesses. It is not the same thing as weight, which is determined by the mass multiplied by the force of gravity. Weight is a force; mass is not. Unless we begin moving near the speed of light, mass remains constant. An object's weight is not constant and on earth, it is determined by the earth's radius at that point. But let's not get caught up in splitting hairs and turn this caliber war thing into a math discussion.
A bullet's momentum can be thought of as how much "push" or "shove" it has. Though it has been known for decades (at least since the century old Thompson-Legard tests), neither the .45 or any other round tested at that time has enough "shove" to knock a human being down. Indeed, when bullets were shot into corpses suspended by the neck using rope, movement was documented as minimal at best. In other words, the .45 auto will not physically "knock" a man down…and neither will a 9mm. If you see claims otherwise, the writer may actually be reported a physical event that he truly thought he observed, when in fact it was caused by the target's nervous system's response to the bullet impact, but it was not from momentum. None of the commonly used defensive handgun calibers pack enough momentum to "knock" any human down.
Kinetic energy, the ability to do work based on an objects speed, has pretty much become a dirty word in some of the stopping power community. It is a physical quantity defined by the one-half of the bullet's mass times its velocity squared. Thus, a bullet's kinetic energy goes up rather dramatically with but relatively small increases in its speed. In the case of the 9mm vs. 45, some 9mm loads can truly possess greater kinetic energy than some .45 ACP loads, but does that in itself indicate that the 9mm is better or even equivalent? Few subscribe to the "energy dump" theory anymore and many answer with a flat out "no." Me, I'm not so sure of its degree of relevance, but neither am I inclined to just dismiss it entirely. Here's why.
When a handgun bullet smacks a "soft target", it creates two cavities. One is permanent and tissue is crushed, cut or displaced permanently from the resulting wound channel. In animals (including man) the cavity will almost always collapse to some degree and will be visibly smaller than the recovered bullet's diameter. The other cavity is temporary. It can be thought of as a "ballooning effect" in which tissue is pushed outward and away from the bullet's path. It lasts but a few milliseconds before collapsing. In the past, the size of the temporary cavity was considered a factor in a bullet's ability to stop. Today, some folks still believe that it is, while others dismiss it as having no relevance whatsoever.
The latter group suggests that unless this occurs near a large vessel or inelastic organ, no permanent physical damage occurs. I believe that this is true; physical damage probably will not occur with a majority of shots, but I am not inclined to say that it still might not factor into the stopping power phenomenon. I do think that its value might be near impossible to quantify because that would depend upon where the target was struck. A rapidly expanding, relatively high-velocity 9mm JHP through an inelastic organ such as the liver might very well create more permanent damage than a slower moving expander from a 45. Does this necessarily mean that a larger temporary cavity that creates no permanent damage has nothing to do with stopping power? I remain unconvinced that it might not contribute to some degree. If so, it means that there is something missing in the small-and-fast vs. big-and-slow, which pretty much sums up the 9mm vs. 45 debates.
I have seen greater-than-expected damage done to smaller critters like fox and raccoons that were hit with high-velocity expanding 9mm bullets. Does this mean that this phenomenon translates to larger animals such as 200-lb. bipeds? Not necessarily, but neither should it automatically be discounted in my opinion. The temporary cavity's rapid ballooning out might very well not do permanent damage, but might not the effect of rapidly moving organs away from the bullet's permanent channel create some effect? As an interested layman, I do understand that at most velocities (offered by conventional defense handguns) the temporary cavity usually does not offer permanent physical damage. It therefore does not contribute to a bullet's lethality or "killing power" but I am not convinced that it is meaningless in the area of "stopping" effect. That said I can offer no help in how to better understand its contributions. I truly wish that someone could find the possible relationship this factor might play.
Let's compare the "heavy" 147-gr. 9mm to the ever-popular 45 ACP 230-gr. bullet. Some that I have actual velocity figures for are Remington Golden Sabers.
From a 9mm Browning Hi Power, the Remington 147-gr. Golden Saber averages about 1030 ft/sec and most expansion/penetration tests in bare 10% ballistic gelatin show an average penetration of about 14 inches with expansion being in the neighborhood of about 0.67". From a 5" Kimber the 45 ACP 230-gr. Golden Saber did 870 ft/sec. It normally does about 14" according to the gelatin shooters and expands to around 0.75".
Thus, the 230-gr. Golden Saber leaves the muzzle with about 84% of the same company's 147-gr. 9mm velocity. Penetration depths are equivalent and the expanded 9mm offers 80% of 45's expanded frontal area. In this instance, the loads appear to be in the same general ballpark with regard to permanent damage considering that in real tissue and bone, bullets do not expand with the same consistency as in gelatin. This is also why the "heavy bullet" 9mm expanding bullet is favored by more than a few 9mm users.
In the past, I was fervently opposed to this approach to 9mm ballistic enhancement. This was because reports from real world shootings were not all that encouraging. With today's better performing JHP's that actually do reliably expand at the actual velocities generated, the approach seems to be working considerably better than the early JHP's in this weight. At least this is what my own (and others') "anecdotal" after action reports seem to indicate. If you believe that expansion and permanent cavity depth and diameter are the only physical aspects of a bullet's lethality, the current 147-gr. JHP's from Speer, Remington, and Winchester could be very hard to beat.
Yet, on animals from the size of Texas whitetail deer to javelina, I have seen the high-velocity 9mm JHP in +P trim demonstrate better than expected "stopping" and "killing power." This includes both 115-gr. +P loads from Corbon as well as the Federal +P+ 115-gr. law enforcement loads. Yet neither penetrates the mandated 12" minimum in ballistic gelatin. The Corbon frequently hits around 1400 ft/sec from my Hi Powers with the Federal version about 50 to 60 ft/sec behind. Either of these two 9mm rounds get around 10" penetration in gelatin, falling shy of the FBI's original penetration requirements. At the same time, in the animals I've shot with these loads, damage has been more than expected. People I've visited with who used these against human aggressors have spoken only of the round's actually decking their opponents with but one to two shots. I have heard almost repeat versions of this with the fast-stepping 185-gr. Corbon .45 ACP +P. It usually penetrates an inch or so shy of the 12 inch minimum.
The entrance wound on the left was made by a 230-gr. 45-caliber Golden Saber. The one on the right was made by a 9mm 127-gr. Winchester +P+. These pictures are not to scale, but the entrance holes inside these two whitetail deer were very similar in appearance. The one on the left was merely taken at closer distance than the 9mm-wound picture.
I think that I might be able to explain at least some of the reason(s). Anyway, here is what I think. See what you think about it.
First, on the Texas whitetail deer that I have (legally) shot and stopped (all of them) with one shot from a 9mm using the Corbon (or its equivalent) shots were only taken at close range. The shots were placed in the heart area and only broadside shots were fired. If there was any doubt about the shot "feeling right" it was not taken. On the deer shot broadside, the torso was roughly the same thickness as a straight-on frontal shot on a human being. While none of the bullets completely penetrated the deer, they all showed evidence of rapid expansion and fragmentation. In a couple of instances, the recovered bullet was found barely inside the rib cage of the animals opposite side from the bullet's entry. Two deer that I cleanly killed with handloaded Sierra 185-gr. JHP's (Corbon-equivalent in velocity) reacted no differently and inside, they showed about the same results.
Had any of these shots been made from less than ideal angles, the results might very well have been drastically different and inhumane.
One of the men I've talked with extensively about his very satisfactory experience against humans with Corbon's 9mm JHP +P is primarily a .45 ACP devotee. Yet he advises that he believes the Corbon fast stepping 115-gr. 9mm to be a stopper. Admittedly, his two experiences would be deemed "statistically invalid" but such were his observations. In the real world, it is hard for a man to discount what he has seen with his own eyes. He hit them "hard" and both went down for physiological reasons rather than psychological ones, but does this mean that each and every similarly hit aggressor will drop like a rock? Nope! I don't believe so. From reading what coroners report, even though visually similar or even identical, no two gunshot wounds are. Differences may indeed be minor or two seemingly equivalent hits may result in very different bullet paths inside the body.
Yet, both the aggressively expanding high-velocity 9mm and .45 rounds discussed have large-for-caliber temporary cavities from what I've read in the literature of those measuring them in ballistic gelatin.
All I'm suggesting is that the temporary cavity may offer some contribution to the rapid collapse of an animate target and offer up a call for not just dismissing it because it is so difficult to relate to the real life mechanism of collapse.
That said, if I had to choose only between a bullet's ability to create either temporary or permanent cavities, I'd go with the latter. This is why: marksmanship. Whether it is a .45 ACP or a 9 x 19mm, I do not believe that either possesses enough "whammy" to deck an opponent rapidly unless he is struck in a vital organ or a major blood vessel is cut. If only lungs are punched as can be the case with the often mentioned "torso hit", it seems reasonable that more rapid incapacitation might occur with the biggest hole. Would the difference be 1, 2, or 10 seconds? That I simply do not know. I am not convinced that anyone does.
If facing an opponent head-on and the shot hits the aorta, or severely damages the heart, I question how much difference (if any) the effect would be between a 9mm with any expanding load or the .45 ACP with expanding ammunition.
I do not believe that a fringe hit with the best .45 ACP load (whatever that is) will be superior to a better-placed hit with 9mm expanding loads.
Neither am I convinced that the expanding bullets in either caliber that have the largest diameters are necessarily always better than those that do not. They may make a larger permanent cavity and maybe more copious bleeding, but might not the smaller expanded bullet diameter moving through vitals at higher velocity be "stopping" via some other mechanism? Here are some examples of why I'm asking this question.
In far south Texas, I was privileged to handgun hunt javelina with some really good pistol shooters. Handgun calibers used were primarily .45 ACP…and my 9mm, which drew quite a bit of good-humored joking around. One javelina was shot with a Thompson-Center .223 handgun and another with a .40 S&W, but the majority was shot either with 5" 1911's or my Browning Hi Power, CZ-75 and SIG P-210. The camaraderie and hunting were great fun, but we shot enough javelinas over several trips that certain observations were repeatedly observed…and not just by me.
Ammunition used included the following in .45 ACP: Federal 230-gr. HydraShok JHP's, Federal 165-gr. HydraShoks, Remington 230-gr. Golden Sabers, and Winchester 230-gr. Ranger LE JHP's. In my 9mm, I tried handloads using Hornady 124-gr. XTP's loaded to 1240 ft/sec as well as a now-discontinued Corbon factory load using the same bullet at about the same velocity. I also used the old Triton 135-gr. JHP +P and the same company's 125-gr. Quik-Shok +P.
Of all of these 9mm/45 pistol rounds, not one permanently decked the tough little 35-lb. javelinas with a single shot unless the brain or spinal column was hit. (Hmmm! That sounds surprising like what we hear on what to expect from human aggressors vs. handgun stopping power.) The single javelina felled by but one broadside torso hit was with the Thompson-Center .223 pistol using 40-gr. V-Max bullets. It is interesting that the animal was downed, but not out when the hunter and myself approached. He fired a finishing shot into the body cavity and the animal was dead, but a very interesting effect was seen. At the hit, what appeared like a donut just under the hide raised around the bullet hole. It disappeared within a few seconds. I had not seen this effect before and have not since.
Using any of the .45 ACP (except one) or 9mm loads (except one), the observed effect on broadside hits were almost always identical. The javelina would collapse, kick a few seconds, and then run a few yards before shuffling off of its mortal coil. All of the 230-gr. JHP's performed about the same although one 230-gr. HydraShok hit bone, plugged, but penetrated only about 4". I still wonder if that round was perhaps defective. The only .45 ACP load that consistently failed was the Federal 165-gr. HydraShok. When hit the animal would not fall, but would immediately take off at full speed. It took quite a bit of trailing to find and dispatch them in most cases. The 165-gr. HydraShok never did penetrate over 3 or 4". We quit using it altogether on the javelina and I shot up what I had at home in case it might accidentally get into one of my "serious" 45's.
The Winchester and Remington rounds performed the same in terms of observed effects.
My 9mm with the rounds mentioned, performed precisely the same with regard to "stopping" the tough little animals. The XTP bullets normally go to about 1.5 x caliber and are not considered aggressive expanders. They are frequently shunned as defense loads because of this and concerns about overpenetration. In the javelina, straight-on broadside shots usually resulted in complete penetration. Angling quartering shots usually showed 12 to 14" penetration and very uniformly expanded 9mm bullets.
Neither my companions nor myself observed any differences in "stopping power" between the 9mm and .45 ACP on these "devil pigs." Yet I know that the .45 with these expanding bullets must leave a larger permanent wound channel. I do not insinuate that the observations made necessarily exactly translate to human targets, but I do note that there absolutely was not the difference in effect that some might lead us to have expected.
The oddity 9mm failure occurred with the Triton Quik-Shok and from the CZ-75. I shot the animal at about 20 yards, angling the shot through the right-side ribcage toward the heart. I was slightly behind the animal and it was a forward angling shot. I fired and the animal simply ran off.
Later that same afternoon, a friend killed what turned out to be the same javelina I'd shot with his forty; I do not remember the load. When it was opened, to our surprise we found that my 9mm Quik-Shok had merely deformed and followed the contours of a rib all the way around, but stopped about 4" from the spine. There was no visible damage other than to the rib the bullet followed.
(Lest anyone think that this phenomenon is limited to 9mm, I'm aware of an incident that occurred years ago in an east Texas town. A 45-toting would-be robber confronted a man working in a bank. He wound up shooting the bank employee during a struggle over the gun. The 230-gr. FMJ bullet hit and broke a rib, but traveled around the outside of the man's body. Despite this painful but ineffective wound, he beat the felon severely with the 1911 pistol.)
Neither the .45's nor the 9mm worked flawlessly with all ammunition. The Quik-Shok load mentioned had worked fine on two other javelinas. The 45-caliber 165-gr. HydraShok failed on all and was discarded, but even the still-popular 230-gr. HydraShok failed to expand once and offered very minimal penetration. As was mentioned earlier, this very well might have been one of the relatively rare cases of a defective or half-loaded round getting out of the factory; I flat do not know but it would explain why the bullet acting like a FMJ solid offered such minimal penetration.
FWIW, the 9mm XTP at about 1240 ft/sec, as well as the Winchester Ranger and 230-gr. Golden Sabers worked consistently well, but to my eyes none performed better than the other. If viewing only the javelina at the moment it was shot, I wouldn't have been able to say whether it had been shot with 9mm or 45 ammo!
Shown are two expanded Hornady 9mm 124-gr. XTP bullets. Both were fired from a Browning Hi Power. The bullet on the left was removed from a javelina. The one on the right was shot into water. The XTP bullet is not known as an aggressively expanding JHP. Yet this bullet at about 1240 ft/sec seems to work just as good as other expanding 9mm loads as well as some of the more popular .45 ACP loads. I do not have a surefire explanation why.
The Texas whitetail deer I've shot with 9mm, 38 Super, .44 Special, .45 Colt and .45 ACP have been pretty uniform in their responses to being shot. A few were instantly incapacitated and never got to their feet; they kicked a bit and then were done. Most jumped, ran a few yards and then keeled over. This is what I've seen time and again with these calibers. I have not used the big magnums considered more appropriate for this type activity so I cannot accurately comment on them. The interesting thing to me is that these smallish 110-lb. animals reacted essentially the same way whether hit with a 124-gr. 9mm XTP at 1240 ft/sec or a handloaded 255-gr. CSWC @ 900 ft/sec from the .45 Colt revolver! Those shot with 230-gr. Golden Sabers handloaded to about 950 ft/sec reacted most similarly to the ones shot with my 38 Super's 147-gr. Golden Saber at just under 1200 ft/sec! (Please note that I am not recommending any of these calibers for "deer hunting." These shots were all at close range and took place over a period of years with more shots passed than taken.) I cannot explain why the effects were almost always so similar, only that this is what was seen, and submit that perhaps there is more to the equation than simply expansion and penetration.
While still a police officer, I was involved in a case in which a small woman ran two city blocks to where my partner and I were handling a different situation. She had been shot through the chest with a .45 ACP 230-gr. FMJ from a 5" Llama pistol. She was not feeling all that good, but was on her feet when the ambulance arrived. I asked her how she ran all that way. She said, "I had to. That mXXXXfuXXer was gonna shoot me again!" It turns out that only her lung (don't remember which) was penetrated and the bullet entered and exited between ribs. Had this happened with a 9mm, some would chalk it up as being about normal for the round. I personally was not surprised.
Several years earlier a ranch where I hunted was overrun with jackrabbits and I shot more than a few with both .45 1911's and my 9mm Browning Hi Power. I "tested" different expanding bullet handloads on these critters, but I needed a baseline so several of the jacks were shot using 115-gr. 9mm FMJ and the traditional 230-gr. FMJ from the 45's. Unless the animals were hit in the forward third of the body, they simply ran off when shot. Sometimes they made it a few yards and other times farther. This was circa 1971 or so. I witnessed this many times and decided that while the then common wisdom decreed that 9mm ball was lacking for self-protection, so was the big 230-gr. 45. To me, if neither would reliably deck a 7-lb. jackrabbit, how could I expect it to do so against a grown man? Yet, another aspect of stopping power was also demonstrated. If the animals were hit in the forward third of the body, the bullet's impact at least had a more immediate effect, i.e., marksmanship counts. Where you put the bullet greatly affects its terminal efficiency.
As an interested layman, I humbly suggest that there may be more to handgun stopping power than is indicated by penetration depths and wound channel measurements. I am not implying that these are not meaningful or of use, but only that there are some things that the homogeneous gelatin might not reveal concerning what makes living animals (including man) cease and desist.
Conclusion and Thoughts on 9mm vs. 45ACP:
I believe that we will continue to see stunning successes and dismal failures with all commonly used defensive handgun calibers including the 9mm and .45 ACP.
An experienced old lawman once told me that a man can be the easiest or the hardest "critter" to put down and the problem is that you never know which you're getting. I think that maybe what he was trying to say is that while a man is an animal, wild animals are not men. If a man is shot and thinks about what has just happened, his human drive to survive may include stopping what he's doing or begging for help. A javelina or deer or bear, etc will not stop until it physically can do nothing else. On the other hand, if a shot man simply reverts to some primordial anger or rage (I'm not sure what to call it) and simply lets his animalistic side come out, he may very well be a most difficult opponent. For 200-lb. animals, we sometimes see even high-powered rifles fail to provide instant "stops." I do not know how to factor in the adrenaline dump that can occur when we're suddenly injured or realizing that we must fight to survive, but I do believe that all of the preceding can play a significant role in the area of stopping power.
If looking only at their "man stopping" abilities, I believe that the .45 ACP with expanding bullets is more effective than the 9mm loaded with expanding bullets. Having said that, I do not feel undergunned with either and frequently carry a 9mm for self-protection rather than the .45 ACP.
After looking at 9mm vs. 45 ACP for over 30 years I am convinced of only one thing: The more I look at it, the less I am sure of.