.40 S&W capabilities

Steven Cali

Member
Network Support I
#1
Kinda strange question that I can't find a satisfactory answer to, so I figured I'd ask it here, considering P&S seems to have the best signal to noise ratio on the internet.
I believe we are all in agreement around here that there is minimal difference in terminal effect between the common service pistol cartridges, since they all expand to roughly the same diameter, give or take a tenth of an inch or so, and all penetrate roughly the same distance, give or take a couple of inches.
The thing that keeps bugging me is that it is also easily established that .40 S&W has more energy to work with than 9mm, which we can reasonably say is the yardstick by which other cartridges are measured, and energy is a measure of the amount of work a bullet can do.
So what work is the extra energy doing? There is a slight increase in expansion and penetration, but it doesn't seem to be entirely in keeping with the increase in energy.
 
#2
The clearest explanation I’ve observed and been told is this. Faster bullets expand quicker and stop faster. Slower bullets expand slower and stop slower. The result is equal penetration.
The basic factor is pistols suck at stopping people. Our MEs have said they can’t determine what paths through a body were made by a 9mm or a .45.
 

Steven Cali

Member
Network Support I
#3
The clearest explanation I’ve observed and been told is this. Faster bullets expand quicker and stop faster. Slower bullets expand slower and stop slower. The result is equal penetration.
The basic factor is pistols suck at stopping people. Our MEs have said they can’t determine what paths through a body were made by a 9mm or a .45.
I agree, and while it does make sense, it still doesn't explain why .40, which generally speaking runs at about the same velocity, give or take a bit, as 9, but with significantly heavier bullets, exhibits similar penetration and expansion. It ought to either expand significantly larger, which would slow forward movement more quickly, or penetrate significantly deeper, slowing down over a greater distance.
I don't dispute that pistol calibers generally suck at physiologically stopping people, I really just want to find out where all the extra energy goes.
 
#4
It usually goes into breaking glock 22 slides.

In all seriousness that’s way beyond my simple mind. There’s a handful of guys here that truly understand the ballistic voodoo and I’d like to hear as well.
 
#5
Kinda strange question that I can't find a satisfactory answer to, so I figured I'd ask it here, considering P&S seems to have the best signal to noise ratio on the internet.
I believe we are all in agreement around here that there is minimal difference in terminal effect between the common service pistol cartridges, since they all expand to roughly the same diameter, give or take a tenth of an inch or so, and all penetrate roughly the same distance, give or take a couple of inches.
The thing that keeps bugging me is that it is also easily established that .40 S&W has more energy to work with than 9mm, which we can reasonably say is the yardstick by which other cartridges are measured, and energy is a measure of the amount of work a bullet can do.
So what work is the extra energy doing? There is a slight increase in expansion and penetration, but it doesn't seem to be entirely in keeping with the increase in energy.
A .1" increase in expanded diameter equates to around a 30% increase in surface area for an expanded bullet... That's a LOT of extra drag created through whatever medium the bullet is flying through.

Also you'll sleep better at night when you come to the realization "energy" means NOTHING when it comes to terminal ballistics. A tiny, lightly constructed bullet at high velocity can have lots of energy and extremely poor effects on target. Likewise a big heavy round nose bullet with plenty of energy that doesn't expand can pencil through leaving a tiny wound channel.

At the end of the day the energy imparted by your bullet on the target can not exceed the energy it imparts on your hand as recoil, Newtons Third law and all that...

The only thing that matters at the end of the day is what kind of permanent wound channel the bullet leaves.
 

Steven Cali

Member
Network Support I
#6
A .1" increase in expanded diameter equates to around a 30% increase in surface area for an expanded bullet... That's a LOT of extra drag created through whatever medium the bullet is flying through.

Also you'll sleep better at night when you come to the realization "energy" means NOTHING when it comes to terminal ballistics. A tiny, lightly constructed bullet at high velocity can have lots of energy and extremely poor effects on target. Likewise a big heavy round nose bullet with plenty of energy that doesn't expand can pencil through leaving a tiny wound channel.

At the end of the day the energy imparted by your bullet on the target can not exceed the energy it imparts on your hand as recoil, Newtons Third law and all that...

The only thing that matters at the end of the day is what kind of permanent wound channel the bullet leaves.
Ah, that makes sense. I hadn't considered the surface area, only the expanded diameter and penetration.
I was already on board with energy meaning very little in wounding but it is a way to quantify the amount of "work" a projectile can do before it comes to a stop, and I was having trouble figuring out how the extra energy was being expended.
 

ggammell

Established
Network Support I
#7
Also keep in mind that bullets are designed to work with certain parameters. 12-16” or whatever so they have to do a minimum and over max is frowned upon. They are engineered to stay within that zone.
 

shoobe01

Regular Member
#8
...It ought to either expand significantly larger, which would slow forward movement more quickly, or penetrate significantly deeper...
Covered well under other answers, but let me nitpick this:

Significantly.

Significance is a statically meaningful thing. A stolen def is "Statistical significance is the likelihood that a relationship between two or more variables is caused by something other than chance."

The way I've thought about it for 20 years or so is related to the "all handguns suck" issue; the maximum-weight/speed cartridges that fits in a gripframe and can be fired one handed by a human, are in a very narrow range, so terminal effects are literally statistically insignificant:
...Our MEs have said they can’t determine what paths through a body were made by a 9mm or a .45.
We can't experiment, so what counts as data is not differentiable.


(People who work on terminal ballistics for a job (or serious hobby) say things along the lines that bullet construction matters more than cartridge choices, at least within the basic mid/large bore cartridges. So that might be interesting to look at along these lines also.)