FMJ Effectiveness in Different Calibers?

[john c]

I recently read an excerpt from the US Army Medical Corps evaluation of wound trauma in WW2. (Sorry, I lost the link) The upshot was a criticism of the .45 ACP with it's lower muzzle velocity compared to enemy handguns. The report observed that handgun bullets with muzzle velocities greater than 1000 fps would shatter bone to a greater degree than .45 hardball.

With a much greater understanding in wound ballistics over the intervening 75 years, what is/are the current conclusions?

From what I've read, there isn't much difference in wounding between .38 spl LRN 158 gr, 9mm and .45 RN FMJ. All of which have small wound channels due to the round nose shape of the bullet disrupting little tissue. The overpenetration means that the bullets almost always exit. Is the main difference in the rounds' effectiveness the degree in which bones are broken?

[BehindBlueI's]

I don't think I know enough to say how much shattering you get, but .380 will break a femur. The differences lie primarily in how easily the round nose profile is deflected and how they deal with intermediate barriers. The bulk FMJ isn't bonded and sheds it's jacket. Higher velocity smaller bullets fragment easier. The .45 Auto will still shed it's jacket but, even if it fragments, the lead core is still heavier then a 115gr 9mm when it started. Something hard cast or "premium" that is designed to not fragment in intermediate barriers/bone strikes etc. would probably fare better.

[Nephrology]

In my limited experience, most centerfire handgun cartridges can and do, fairly frequently, fracture ribs and long bones (most extremity GSWs go to ortho for fracture repair if they are hemodynamically stable with no other injuries). Because we don't pull em out and measure em, I have to estimate caliber based on what the bullet looks like on portable X ray. Fairly often it is too mangled to identify.

My guess is the 1940s study you read used methodology that was ... less than perfect. I wouldn't over-interpret their results. All bullets hurt pretty bad. All things considered, I doubt there is a terribly meaningful difference between equivalent quality 9mm and .45 ball.

[JRV]

I have seen bodies killed by .22s and .25s and I fought a guy whose skull deflected a 9mm ball round.

Any study of uniform effect on bone would basically meaningless, because removing variables for a fixed data set leaves you with results that are borderline extraterrestrial compared to field conditions. People have different amounts of muscle and fat and sinew, and bone density varies from person to person.

Basically, any mainstream pistol round will penetrate any bone that’s not a pelvic girdle, unless it is deflected, or, in a mouse gun round, forced to go through thick clothing, excessive fat, and muscle.

Based on my hunting results and those of people around me, if I have to carry a non-expanding pistol bullet, and I want to minimize deflection issues and guarantee penetration through bone, I want a flat meplat in something heavy for caliber.

[BigT]

My wife knows from first hand experience 9mm ball will devastate a pelvis.

















No I Didn't shoot her

[Velo Dog]

From what I've read, there isn't much difference in wounding between .38 spl LRN 158 gr, 9mm and .45 RN FMJ.

"The kinetic energy lost by both 9x19mm and 45ACP handgun projectiles, FMJ and JHP, was essentially identical in all three target sets."

http://www.brassfetcher.com/Simulate...Shotlines.html

http://www.brassfetcher.com/Simulate...an%20Body.html

[Joe Mac]

My wife knows from first hand experience 9mm ball will devastate a pelvis.

















No I Didn't shoot her

So...she shot you?

[pettypace]

Maybe the 9mm will shatter more bones. According to Hatcher, the 9mm FMJ will penetrate nine 7/8" pine boards while the .45 FMJ will only do seven pine boards. And maybe punching through pine boards is somehow related to shattering bones. But I'm guessing that after a two or three pine boards (or however many bones that equates to) both bullets have breached the armor plate and reached the vitals.

I'm also guessing that Hatcher had nothing to do with that Medical Corps report because there's no question that Hatcher figured the 45 ACP was much more effective than the 9mm. How much more effective? Twice as effective according to Hatcher's momentum based "Relative Stopping Power" scale where the 45 ACP gets an RSP of 60 compared to the 9mm FMJ which only gets a score of 29.4.

Elmer Keith would certainly side with Hatcher in favor of the .45 ACP. For example, from page 279 of Sixguns, Keith wrote (of the .38 ACP, .38 Super, and 9mm Luger) "They are the best small caliber auto pistol loads for any defense work, but never the equal of the .45 auto for such usage, except for brain shots on a bull or similar animal." But I doubt that Army Medical Corps report was much concerned with brain shots on bulls.

What would Fackler say? Here's a Fackler profile for the 9mm FMJ:



and for the .45 FMJ:



They'll both penetrate over two feet of ballistic gel and more than likely go through and through most bad guys with or without bones. Of course, the .45 makes a bigger hole and more wound mass. Using the equations and parameters from Quantitative Ammunition Selection by the Schwartz I get a 34 gram wound mass for the 9mm and 50 grams for the .45. Of course, with through and through penetration, some of that wound mass is in thin air. So, maybe MacPherson's wound mass estimates of 16 grams for the 9mm FMJ and 26 grams for the .45 FMJ are more realistic. But either way, the .45 comes out ahead.

If I had to choose between a Luger and a 1911, each with a full magazine of FMJ, I'd take the .45. Between a Hi-Power and a 1911, each fully loaded with hard ball, I'd go with the Hi-Power.

[willie]

So how well has the 9mm performed for our troops when it was used to shoot the enemy?

[BigT]

So how well has the 9mm performed for our troops when it was used to shoot the enemy?

Internationally it works better than expected when it hits important things and badly when it doesn't. Like most things.