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9mm
Kendahl:
The FBI penetration standard came out of the 1986 Miami shootout during which they lost two agents killed and five wounded. The agents scored good hits on the bad guys but their bullets failed to penetrate deeply enough to reach vital organs.
The link only mentions 9 mm, .40 S&W and .45 ACP. Until the study is published, we won't know if other calibers were considered. The FBI's conclusions match those of Ohio police officer and instructor Greg Ellifritz. He published his analysis of 1,800 shootings over a period of ten years on his blog under the title An Alternate Look at Handgun Stopping Power and as a somewhat simplified article in American Handgunner exactly a year ago. Ellifritz's data include shotguns (mostly 12 gauge) and centerfire rifles. It should be no surprise that they were far more effective than any handgun. The only thing that bothers me about Ellifritz's study is that, although he mentions statistical significance, he never quantifies it. Therefore, we can only guess how big a difference must be before we can attribute it to performance of the cartridge rather than random chance. Ellifritz says that failure rates between 13% and 17% for calibers from .38 special to .45 ACP imply that they are similar in performance. It may be significant that the failure rate for .357 magnum (including .357 Sig) is only 9%.
It's simple physics that shooting a given bullet faster or a bigger, heavier bullet at the same speed will be more effective. However, physics can't determine whether small and fast is better or worse than big and slow.
Compared to more powerful cartridges, 9 mm has three advantages. They are controllability, magazine capacity and cost. Better controllability results in more hits in less time and fewer misses to endanger bystanders. Lower cost means that more practice rounds can be fired for the same expenditure. The benefits of greater magazine capacity should be self evident.
.327 magnum may be an exception to the rule "Nothing smaller than a .38" since it falls between the .38 special and .357 magnum in power. In a revolver like the Ruger SP101, it gives you six shots instead of five.
SeanN:
Just wanted to add that they consider 12" (not 14-16") as the "gold standard" is for several reasons:
1. Because the FBI established it as their baseline minimum penetration for maximum effectiveness. (And thus, a lot of people mimicked that requirement but it is a smart one)
2. As previously stated there are tons of variations in the amount and types of tissue you may hit depending both on shot placement and on the size/build of the bad guy.
3. Clothing varies and can actually make a substantial difference in wounding potential of a round (heavy winter jacket, multiple layers of denim, etc. vs "naked")
4. It's quite possible to have the bad guy have an arm in the way of the shot. Having the ability to penetrate through an additional few inches of tissue, muscle, and possibly even bone may be required.
5. For some, the ability to shoot through intermediate barriers is a major concern. For civilians, probably less so than for law enforcement but it may be a good decision (depending on the scenario).
Basically, you need to ensure you can hit the vital points and stop the threat. Requiring at least 12" of penetration in ballistic gel gives you a good baseline for effective terminal performance in a wide variety of situations.
JTH:
--- Quote from: SeanN on October 02, 2014, 08:30:48 AM ---Basically, you need to ensure you can hit the vital points and stop the threat. Requiring at least 12" of penetration in ballistic gel gives you a good baseline for effective terminal performance in a wide variety of situations.
--- End quote ---
Yep. The FBI, in their discussion of use of gel (if I recall correctly), even talked about how gel itself is not supposed to be any sort of official simulation of a human part. Instead, it is merely an objective way to measure a given minimum amount of performance. 12" of gel penetration does not equate to 12" of human body penetration, nor is it supposed to do so.
Lots of people act like it is supposed to be a simulation, but it isn't. :)
And they aren't saying that 12" of penetration means one-hit stops. Or even that more than 12" of penetration means better performance. (Up to a point, yes, but 18" isn't necessarily better than 14".)
JTH:
--- Quote from: Kendahl on October 01, 2014, 10:19:26 PM ---...Greg Ellifritz. He published his analysis of 1,800 shootings over a period of ten years on his blog under the title An Alternate Look at Handgun Stopping Power and as a somewhat simplified article in American Handgunner exactly a year ago. Ellifritz's data include shotguns (mostly 12 gauge) and centerfire rifles. It should be no surprise that they were far more effective than any handgun. The only thing that bothers me about Ellifritz's study is that, although he mentions statistical significance, he never quantifies it. Therefore, we can only guess how big a difference must be before we can attribute it to performance of the cartridge rather than random chance. Ellifritz says that failure rates between 13% and 17% for calibers from .38 special to .45 ACP imply that they are similar in performance. It may be significant that the failure rate for .357 magnum (including .357 Sig) is only 9%.
--- End quote ---
Here's one link to E's article:
http://www.buckeyefirearms.org/node/7866
An interesting read.
--- Quote ---It's simple physics that shooting a given bullet faster or a bigger, heavier bullet at the same speed will be more effective. However, physics can't determine whether small and fast is better or worse than big and slow.
--- End quote ---
I'm not sure I would agree with "more effective". I'd certainly go with "possibly more effective" but that isn't the same thing. (And given certain limits, I don't think it is right, though that is a personal opinion.)
For example, shooting a 50BMG at 3500ft/sec or 3800 ft/sec would make little difference in terms of wound ballistics at 200 yards, even though that 300ft/sec difference is quite a lot. :)
In a similar fashion, shooting a 9mm 124gr bullet at 1050 ft/sec versus 1120 ft/sec might make a difference in effectiveness, but we don't actually know that. (And while I agree it does makes a difference in terms of kinetic energy and momentum, I don't actually think that difference makes an effective difference in 9mm performance in terms of stopping an attacker.)
Pistol performance for physiological stops, according to the research I've read, generally seems to sum up to:
-given certain minimum performance characteristics (12" FBI standard, for example), physiological stops only occur quickly with shot placement on CNS, and physiological stops do not occur quickly with any caliber/round type with shots not on CNS, barring LOTS and LOTS of hits
-physiological stops may occur due to the sum of all damage, but unless damage is in CNS, sufficient damage to create a physiological stop requires multiple hits and lots more time than we want to wait
-psychological stops will occur with any round effectively equally, and shot placement itself does not seem to have a major effect.
Pistol rounds simply are so bad at damage (compared to long guns, for example) that minor differences between round velocities create an effectiveness difference of basically zero, as long as certain basic minimums are met, with regard to physiological stops.
(Occurs to me to add: "Physiological stop" means that the attacker is physically incapable of responding, no matter their mindset or willpower. "Psychological stop" is when the attacker chooses to stop their attack. Studies show that by far, psychological stops occur much more often than physiological stops, which is why plenty of people have defended themselves effectively with .25s and .22s. Or by taking a shot that missed, and yet that was sufficient to stop the attacker anyway.)
--- Quote ---Compared to more powerful cartridges, 9 mm has three advantages. They are controllability, magazine capacity and cost. Better controllability results in more hits in less time and fewer misses to endanger bystanders. Lower cost means that more practice rounds can be fired for the same expenditure. The benefits of greater magazine capacity should be self evident.
.327 magnum may be an exception to the rule "Nothing smaller than a .38" since it falls between the .38 special and .357 magnum in power. In a revolver like the Ruger SP101, it gives you six shots instead of five.
--- End quote ---
And yet----there doesn't seem to a difference between any pistol caliber, really.
The good thing is that it means (again, given a certain minimal performance level, that 12" FBI is a good generic measure), any pistol will do. And hey, .22s work for psych stops too. :)
Most of the time, for single attackers single shots (or less) are sufficient for a stop. I'm not saying that this is what people SHOULD use as the determining factor for caliber/capacity/round choice, but it does mean that it isn't like I can argue with someone who carries a Beretta Bobcat around as their primary CCW weapon. Or a 2-shot .38 derringer.
Not what I'd choose, but it isn't me. :)
(And for people who want to make certain they can manage physiological stops---again, other than meeting that basic minimum, everything else is up to your particular preferences of capacity, caliber, velocity, loudness, etc...)
David Hineline:
FBI and the police dept. who follow their every move are not going back to 9 MM because it is the best ballistic round. It is due to Political Correctness requiring that tiny men and tiny women get to be police and secret service and military and on and on. The lower recoil of the 9 MM improves the shootabillity of the new smaller/weaker public servants.
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