The following is part of an article emailed to me. It was originally written by firearms trainer Gabe Suarez. Some of what he has written may apply here, although it is mostly talking about the advantage of having a firearm that has a higher magazine capacity. Take it for what you want, personally I agree with him.
"I suppose this will be yet another highly controversial issue, but what the heck. Controversy makes for interesting discussion, no? The issue is to look at whether high magazine capacity gives you a tactical advantage, or if we are better served by carrying an equally sized weapon with a smaller capacity of bigger bullets. Before I answer my own question, let me put forth some facts as seen both in force on force training and on the street.
Point One - Pistol bullets, regardless of caliber are all, what one colleague calls, "iffy". None can be guaranteed to drop an adversary in his tracks reliably. The notion of a one shot stop is an urban myth dreamed up by those with a vested interest in such things. I have seen 45s work and fail, and I have seen 9mm both work and fail. For the record, the only one shot drop (excluding head shots) I have ever seen with a pistol was fired by a good friend as we entered a crack house during a SWAT raid. He shot the bad guy squarely in the heart with 9mm +P+ out of a SIG P-226. He only fired once because the bad guy fell before my friend could reset his trigger for the next shot!
If we look at the three most prevalent calibers we see that there is very little difference between them. A 9mm (also .38/.357) is only one little millimeter smaller than the 10mm (aka .40 S&W), and that is only one little millimeter less than the vaunted 11mm (aka .45 ACP). And before we get into the high speed light bullet versus the heavy slow bullet argument, lets remember that you can only drive a pistol bullet so fast without drastically affecting its integrity. Moreover, since penetration is affected by weight, sacrificing weight for speed will not yield good results. Finally, you can only make a bullet so light or so heavy. There are limits to what you can shoot out of a pistol.
I have seen every one of these calibers fail at one time or another. There are those who disdain the 9mm as unsuitable for anything larger than squirrels. With modern ammunition, this is simply not true. There is also a myth and a cult grown up around the .45 ACP in this country. Sadly, it is not the deadly hammer of god its proponents suggest. This is not new. Read Fairbairn's Shoot To Live. He writes of two separate times when the .45 failed to work any better than anything else. Although one millimeter may give you a slight edge in a less than optimum body hit, under most circumstances, there will be very little difference between the effectiveness of the various calibers when modern anti-personnel ammo is used. Trauma injury doctors and reputable terminal ballistics experts tend to agree with this statement.
Point Two - Private Citizen CCW Operators do not go looking for trouble. If they are called to fight it is either because they have inadvertently crossed paths with bad guys while they are doing bad guy stuff (walking in on a robbery in progress as an example), or because they have been specifically targeted and stalked (such as a carjack, or home invasion event). They will have to use extreme violence to fight off the surprise attackers. When we translate the conversion of fright and startle into a firearm application we wee that definition is high volume of fire. You will shoot a lot, and until the threat is no longer there.
While these events share slightly different dynamics, the common thread often seen is that of multiple adversaries. The lone criminal or terrorist is an urban myth. If your fight only involves one, consider yourself lucky. More often than not you will be outnumbered.
Another point is the time frames in which these events take place. Think three seconds. After this, either you will be dead, or your adversaries will be dead. Urban gunfights do not go for hours. Unexpected, short duration, high intensity, extreme violence, multiple adversaries. That is the back drop.
Point Three - Our staff has collectively been in a large number of gunfights ranging from police, citizen, and military events. We draw on those experiences to set up mock gunfights in dynamic, unscripted force on force training drills. Although the surprise factor is missing (you generally don t know you will be in a gunfight until it is upon you), the dynamics of its evolution do not change much. Here are some other observations from watching hundreds of those drills.
1). Defenders will fire their weapons until the threat disappears. That means that until the role player falls down (simulating effective hits delivered), or runs away (removing the target), the good guy will keep firing. The concept of school solutions, controlled pairs, or otherwise artificially limiting the number of shots (as one does in a firing string on the range) does not hold up even in guys who've been extensively trained to do it.
2). When a training gun stops firing (due to running out of pellets), the shooter is still in the fight and still trying to shoot his enemy as well as trying to not be hit by him. We see them continue to try to work the trigger for one or two times before there is a realization that there has been a stoppage (malfunction or empty gun). This is followed by a visual examination of the gun, and only then is remedial action taken.
This can take upwards f a second and a half before anything is even attempted to fix the gun, and then the additional time needed to reload. Thus the idea that one can read the gun s feel and immediately realize a need to speed load simply does not hold up. Running out of ammo is usually a fight ender if there has been a failure to stop, or there are multiple adversaries at hand.
3). Participants in these reactive mock gunfights are debriefed immediately to get a clear picture of what happened before any rationalization takes place. Besides a shoot them to the ground firing process, most shooters do not remember seeing the crystal clear sight pictures they learned on the shooting range.
We see a great deal of point shooting, and gun index shooting. I have yet to see anyone strike a classic shooting posture and press off a carefully sighted pair in these room distance drills.
The point to remember is that in a fight such as what are likely for the private citizen, one can easily develop Bullet Deficit Disorder , and that this can have deleterious effects on the outcome of that fight.
The idea that a pair or trio of quality rounds carefully delivered onto a high scoring target zone will stop the action fails both the terminal ballistics test as well as the applications test.
A truth of gunfighting - Having more ammo immediately on board lessens the likelihood of ever needing to reload. Not needing to reload translates into more time delivering lead and less time manipulating the weapon. More trigger time increases likelihood of hitting, which increases survivability.
So the question is this. Given that there is a limit to the size pistol one can carry, do I want that pistol to hold more rounds? My answer is a strong YES!
Consider the similarly sized Glock 36 in .45 ACP, and the Glock 23 in .40 S&W. The latter holds nearly twice the ammo of the former in an almost identical package. The Glock 19 is an even more drastic comparison with 15 shots available. Of course there are also high capacity 45 pistols for those so inclined and for those who can wield them. I would argue that if your choice is a 45, a gun holding 13 would be better than a gun holding 6. And if your hand is too small for the 13 shooter, rather than decrease capacity, I d decrease caliber.
I have a colleague is South America who has been in High Risk Police Service for close to three decades. He has been in over three dozen verified gunfight . His weapon was originally a Browning Hi-Power and later a Glock 17.
I was very interested in hearing more so I asked him about the load he used. He said he had always used military ball full metal jacket. Astounded I asked him why he chose that. That is all we can get here. Hollow points are illegal .
I shook my head and told him that there was a belief in the USA that 9mm was an anemic caliber, especially in the load he d chosen. He shrugged and said that his adversaries must not have gotten the word. He said he fired a burst at the chest and if they didn't fall fast enough, he fired a burst at the face. He never needed to reload and had enough on board so if he missed a shot or two he could catch up in the fight. And before we hear the careful shooter versus the spraying prayer, this man is one of the best shots I have seen and competes on an international level. Even so, he knows the chaos in a gunfight can play havoc with even the most gifted marksman. Perhaps we need to take a lesson from him."