Hello, sir. The "caliber war" between 9mm and .45 ACP has been a long one to be sure and one that will continue I suspect.
I will offer some observations and my opinion and keep it as "clinical" and unbiased as I can.
First, it can be shown that the the gunshop owner's statement about the 9mm going through the "target" and then a wall simply is not true unless speaking of FMJ. More than a few 9mm expanding rounds are criticized for not having enough "soft target" penetration. (This was cited as a reason for the Miami Fiasco in which some federal agents were killed after hitting a bad actor with what was described as a "non-survivable" wound, but the expanding bullet stopping just short of the heart after passing through an arm and then entering the chest cavity.)
In sheet metal, the faster 9mm FMJ often will outpenetrate .45 FMJ, but if either hits the typical home or apartment wall missing studs, pipes, etc,
either will penetrate with enough power to cause a dangerous wound.
If either a 9mm or .45 ACP JHP
misses the intended aggressor and then smacks a wall, neither is likely to expand. The JHP "works" by having the pressure inside the hollow cavity so much greater than that outside that it ruptures the jacket which begins folding back allowing expansion. This requires a "wet" medium. If either JHP smacks sheetrock, plywood, etc, the hollow cavity is almost always filled with this "dry" medium and the bullet acts like a FMJ; there may be a bit more deformation (not expansion) than the thicker-jacketed military ball rounds, but they do not expand...at least not in the tests I ran while a tactical officer nor any I've witnessed since.
It seems that the concerns over which caliber usually boils down to something like, "Does the 9mm have enough power?" or "Which is the best "stopper?" Countless trees have been made into paper on this topic and I doubt that this post will settle the matter.
I believe that with FMJ, .45 ACP
is better than 9mm FMJ, but I do not believe that it is as much better as some. I am personally aware of
both doing the trick and both
failing miserably.
I also believe that the best 9mm loads can be superior to some of the .45 loads, but with the
best loads in the latter, it is more potent.
The question is, "What are the best loads?" and there's more than a little controversy and divergent thought on it.
That the .45 ACP
can be more potent than the 9mm
doesn't mean that the 9mm is by definition ineffective, at least not in my observation.
During my years in police service, I had a pretty free hand in what I carried and I carried both the 9mm and the .45 at different times in my career. I never felt undergunned with the 9mm, but preferred a long gun to
either when the opportunity presented itself.
You see, I'm not overly impressed with
any commonly-used defense caliber, be it .38 Special, .357 magnum, .40 S&W, 9mm, or .45 ACP.
Any of these can "stop" a man and any can fail from what I've seen. The combination of a "good" load and more importantly,
placement seems to consistently float to the top as a determining factor, assuming that the person will actually shoot in the first place.
Let's take a look at a couple of loads that usually rate pretty high as capable defense loads for 9mm and .45 ACP: Winchester Ranger JHP.
These are law enforcement rounds sold only to police via a Winchester company policy. The reason I picked them is because they have passed FBI and other serious researcher's testing and folks on most sides of the "stopping power" issue, speak well of them. I've had very good luck with them in my own informal tests and with animals I've shot with both.
Here are three expanded 9mm Winchester 127-gr.+P+ rounds. The one on the left was fired into super-saturated newsprint. The one on the right was recovered from water and the one in the middle cleanly killed a deer. Expansion seems very consistent and reliable through repeated tests. The 147-gr. version seems to work just as well in this regard.
Here are a couple of Winchester 230-gr. expanded Ranger JHP's. They also expand reliably and to a larger diameter than the 9mm.
The "advantage" that .45 ACP may have over 9mm is diameter; it is simply larger. Thus, if the .356" 9mm doubles in frontal area after expansion, it will still be less than the .452" 45 assuming equal expansion. If either smacks the heart, spine, or brain, it makes no difference the caliber, but if we just get the "solid torso hit" so often described in the literature, but in actuality a lung hit and nothing else, it seems reasonable that the larger caliber might incapacitate faster. How much faster? That I do not know. While neither will leave a permanent wound tract as large as its actual diameter, even a milimeter more would result in more copious letting of blood. I'm not sure anyone can predict by how much because each and every gunshot wound seems to be just a bit different.
I'm not on either "side" in this issue. I have and use both calibers and respect both, but to me it seems that more important than 9mm vs 45 is the actual willingness to shoot another combined with the ability to place the hits quickly and accurately. I am well satisfied that this is difficult under stress, but still believe that it is necessary if we want to make the bad guy "stop" because he has to rather than
just wants to.
It is my belief that one reason we fixate on the "best" caliber or load is because it is one thing that we
can actually control...for those who have a choice.
As you mentioned in your post, ammo cost for the 9mm is less than for the .45 ACP and this is true. For some people, this very well might determine how much they practice and if done correctly, how much their skill level does or does not go up. I had much rather face a poorer shot who is unsure of himself but armed with a .45 than a stone-cold SEAL or SAS-type armed with a 9mm using ball!
Thus, this long way around the mulberry bush response says that I do believe that in its better loads, the .45 is "superior" to the 9mm. It also says that I doubt the margin is so great as some do. I suggest not having blind faith in either and that the 9mm definitely
is a viable defense caliber.
These are but a few commercially available 9mm loads available and there is an entry from "old technology" to the newest approaches to increasing "stopping power with commensurate costs. Any of these in my 9mm would not leave me worried about "power."
I was asked the proverbial "Which would you want, a .45 or 9mm pistol, if you had but one round and were locked in a room with a madman with an axe?"
I answered, "The one I could hit the best with."
To me, your friends would be wise to shoot the 9mm pistol before making a decision and then if they want the .45, great. At the same time, if someone simply doesn't trust a certain caliber, it is not unimportant that they go with one that they do trust. There's enough
self-doubt and fear in life-or-death situations without that...just don't trust
either too much. Be ready for quick and
accurate follow up shots and use cover, concealment, and escape if at all possible.
Perhaps this diatribe will be of service, but do not be surprised if it is not.
If I've not already bored you to death, here are some articles that might be of interest to you:
http://www.hipowersandhandguns.com/9mmGoodProtection.htm
http://www.hipowersandhandguns.com/Effective Defense Gun.htm
http://www.hipowersandhandguns.com/Self Defense Caliber or Capacity.htm
http://www.hipowersandhandguns.com/Have No Faith.htm
http://www.hipowersandhandguns.com/SpringfieldXD9.htm
Best.