Here's the thing:
Actual performance of roughly analogous rounds in the 9/40/45 range exhibit almost identical wound profiles in actual human beings. Forensic pathologists won't even mention caliber in their reports as such, preferring language such as "consistent with a handgun wound". Without an actual recovered projectile, there is no way to really tell.
If you are talking strictly FMJ rounds, consider that 9mm is realy 9.01mm, and .45ACP is really 11.5mm. so we're arguing about 2.49mm; about the thickness of two human fingernails. If you think that takes something from "meh" to "awesome man stopper" ...
There will be greater variance in the wound channel based upon the physical makeup of the person shot than based upon the caliber of the round.
Are there differences? Of course there are. Brief primer: diameter alone
is a meaningless measurement for the problem, cross-sectional area (and yes you need diameter or radius to calculate it) is more important. Mass is important, but far less than velocity.
Take the following examples:
- A 230gr projectile @ 1000fps = 510 ftlbs of force.
- A 124gr projectile @ 1000fps = 275 ftlbs of force.
... because mass has a linear effect on energy. Of course .45ACP rounds and 9mm rounds don't typically have the same velocities.
So, so we need a more typical example:
- A 230gr projectile @ 850fps = 368 ftlbs of force.
- A 124gr projectile @ 1300fps = 465 ftlbs of force.
Now, the above is simply a comparison based upon military specs for 230gr .45ACP ball ammo and 124gr 9mm NATO FMJ, but the point remains the same: velocity is much bigger determiner of energy than mass or cross-sectional area. The NATO 9mm simply has more energy than milspec .45ACP, but energy isn't the whole story.
What .45ACP has going for it is conservation of momentum
, as a effect of greater mass. This is why a slower round with less energy can do as good a job as something faster/lighter. Reverse that if you need to do so for emotional comfort.
The 45 does the job by retaining momentum upon impact. The 9mm does it's job by having more energy upon impact to begin with. There are some differences or advantages at the margins to either depending upon what/who exactly you are shooting. They both "work" about the same, as every verifiable test/study/experiment has repeatedly shown.
Is there a difference? Sure ... .45ACP is more easily defeated by soft body armor
than 9mm, for instance. On the other hand, someone wearing a rifle plate
would feel a greater impact with .45ACP than 9mm.
My point is that it a whole lot of stressing about something that will never, ever make a difference in a gun fight or shooting.
Choose whatever you like and learn to shoot it well. That's a far better use of time than stressing over something that is essentially a non-issue, and pretty much settled science outside of gun forums.
I know that physics is boring, and that some people prefer to note guns/calibers used by famous personalities and "been there, done that" guys. The following is a list of calibers and guns chosen by certain famous “cool gun guys” for their own personal self-defense. This information has been culled from various public sources, but cannot be guaranteed 100% at any given time. Also, it’s well known that many of these persons use other calibers or guns in competition or when teaching, and that many have sponsorships with various companies. No meaning is implied regarding the effectiveness of any particular caliber, round or handgun … draw whatever conclusions you wish.
(Last updated 09/12/2012):
Kelly McCann: 9mm Glock 19
Dave Spaulding: 9mm Glock 19 (sometimes Ruger SR9c)
Andy Stanford: 9mm Glock 19
Massad Ayoob: 9mm Glock 17 (sometimes .38 revolver)
James Yeager 9mm Glock 19
Paul Gomez 9mm Glock 19/17
Gabe Suarez 9mm Glock 17
Rob Pincus 9mm unknown (sometimes .38 revolver)
Paul Howe 9mm Glock 26
Travis Haley 9mm Glock 17 (sometimes S&W M&P 9)
Chris Costa 9mm S&W M&P9c (sometimes .45ACP 1911)
Larry Vickers 9mm Glock 19/17
Jason Falla 9mm Glock17
Dave Harrington 9mm 1911-pattern
Bob Vogel 9mm Glock
Michael Janich 9mm Glock 19/17
Rob Leatham .45 Springfield XDS (formerly compact .45ACP 1911 or 9mm XDm compact)
Michael Bane 9mm Ruger SR9c
Pat Rogers 9mm S&W M&P
Mike Seeklander 9mm S&W M&P (alternately a Kahr CW9)
Bill Rogers 9mm S&W M&P