Monday, January 24, 2011

Only reason I'm posting on this is I'll forget to if I don't do it n ow

Huffman has a post that includes this on the subject of bullet penetration:
Penetration less than 12 inches is too little, and, in the words of two of the participants in the 1987 Wound Ballistics Workshop, "too little penetration will get you killed."
Sounds good. But it reminds me of something in the Ayoob book I read. Can't dig it out right now but it goes something like
Saying "A bullet HAS to penetrated 'X' inches as a minimum" has problems. Say you shoot an attacker with a .45; the bullet penetrates the chest, expands to about .65" and stops just under the skin of the back, stopping the attacker cold. According to the 'must penetrate at least' numbers that bullet is a failure because it 'only' penetrated 10.5 inches.

No deep thoughts right now, just something I was reminded of.


Sailorcurt said...

Ayoob and the post Joe linked to were talking about two different things.

The minimum penetration standard is referring to the average or typical penetration of a specific round in Gelatin during testing.

The experts consider 12" to be the minimum to ensure that the round will penetrate sufficiently in a variety of situations to do the job.

Ayoob's example was a real world situation. The very round that, in his example, where the bullet presumably penetrated clothing, the dude's sternum and varying densities of muscle and organ before coming to rest after penetrating 10", may very well have penetrated 12 or more inches in gelatin in a test firing.

You're comparing apples to oranges.

The point isn't that every bullet must penetrate 12" through any material in every situation or it is ineffective, but that sufficient penetration under test conditions is a better indicator of the effectiveness of the round than ephemeral standards like "temporary cavity" or "power factor" that mean little under scientific testing with regard to creating injury sufficient to disable an attacker.

Firehand said...

I shouldn't post when that tired, I don't word things well.

If I remember right(need to find that book) Ayoob was quoting a guy speaking of some lab tests or record comparisons; in that case, the study referenced would have considered that shot a failure specifically because "It didn't penetrate at least 'X'." Which, he pointed out, would be silly because the load performed perfectly. His point was that he considered it important to study the records of actual shootings, not just lab tests on the ammo in question.

Joe Huffman said...

The issue is you need 12" to get to vital organs under near worst case situations such as when going through a bicep and several inches of fat/muscle before reaching the thoracic cavity.

With a some small, skinny bad guy four or five inches of penetration could reach his heart from the right direction but you can't count on having that body type and orientation when you encounter a bad guy. You need to design/select your weapon to take down the biggest bad guy from any orientation presented to you. If you can't then you must be able to get a head shot (tough because it is smaller, has a tough shell, and is much more maneuverable than the thoracic area) or just leave and come back with a rifle when encountering the guy who is 6' 6" and weighs 400 pounds.

AM said...

When discussing lethality:

Accuracy is most important. Failure to connect with your target makes penetration a moot point.

Next is penetration. Will your bullet penetrate to or through a critical area?

Finally expansion, does the bullet cause the maximum permanent wound channel possible?

Now forgive me for stating the obvious, since I load my 1911 with various 230 gr hollowpoints that barely make the 12" rule. The final rule is this:

Keep shooting until the threat is gone. Hit a dude enough with a .22 long rifle and he will stop being a threat.

So a 380 that you can shoot the wings off of a fly at 15 yards is much better than a 40 S&W that you can not control. A 9mm that you can tattoo with is better than a 45 that you can't. Accuracy first, penetration is only a secondary concern.

Joe Huffman said...

It is my understanding that some Eskimos take down polar bears with .22 LRs. Several people will surround the bear and they will each pump dozens of rounds into the animal.

As Greg Hamilton says, "Do you know how to double the effectiveness of any bullet? Put another round through your target."

That said the author of the report was talking about ammo selection which, for the most part, isn't a major factor in getting pistol bullets on target in typical gunfights. Training and practice are the dominate factors in that.

OldTexan said...

A good, long time friend of mine is a Dallas County sheriff’s deputy and he shared this bit of wisdom with me about guns. For a number of years part of his job has been follow up interviews with shooting victims who are still on this side of the ground. He has a .45 for his primary pistol and he carries a small .22 revolver for his backup gun.

I asked him is a .22 is enough gun to be of value and he told me that in a lot of cases with centerfire pistols the person receiving the wound was often unaware that they had been shot at first, there is often a delayed reaction for the body and mind to process the fact that a bullet has punched a hole in a person, they are bleeding and it is not a good thing.

The interesting thing he told me was that in every case he had encountered, and there were a lot, of a person being shot with a .22 there was instant pain and a lot of pain and while it might not disable the person being shot it sure did register on them at once that they had been shot and it was not a good thing to be shot. I never heard of this before but I do know that the man who shared the information with me is a reliable source of information and I think this might be a factor to consider when making a choice of a gun that a smaller person can handle with confidence.

As noted above, accurate fire and a good deal of it beats a whole lot of noise and misses. My wife can shoot a .22 pistol all day long and stay on target but anything bigger and she squints and flinches and loses interest real fast. After hearing about the .22 pain factor I feel better about encouraging her to shoot and use a gun that really is effective in a bad guy encounter, even if it might not penetrate deep enough to make a gun expert happy.