First post here, looking for a big gun forum with lots of ideas and differemt opinions. My question is, do all bullets over penetrate? Now, this is a question I have proposed to myself on numerous occasions because I know people who will only trust their life with JHP in fear of over penetration and some who carry FMJ and won't spend the money on JHP. Here is where I get confused. I have seen multiple tests on 9mm, .40 S&W and .45 ACP where a JHP will pass through 2 different blocks of ballistic gel and keep going sometimes. The ballistics gel size will very, but usually this is between 16 and 20 inches. But even at 16 inches, it seems a little too deep. So my question remains, doesn't most modern self defense ammo over penetrate? Some ammo gets crazy, penetrating over 25 inches so obviously there is still some velocity in those rounds. And if most gun fights (self defense) happen, on average, within 15 to 25 feet of you, should you still worry about over penetration? A lot of people really disown the idea of carrying FMJ or ball, but don't really look at over penetration of hollows either. Please help calrify or throw out ideas! Any ideas anybody might have would be appreciated, I want to start a conversation on this, NOT a debate about one being better than the other. Looking for and open to all ideas / opinions. Thanks guys!

Your post poses a logical question, but I am inclined to question the underlying "facts." I was quite surprised to see you quoting 16 - 20" of ballistic gelatin for JHPs. I wasn't aware that one could always count on that from FMJs!

BTW, there is a notable body of thought that even the danger of overpenetration itself is exaggerated, particularly considering the drastically decreased velocity of a projectile which has passed through a body. Some who share this outlook consider misses to be much more dangerous than shoot-throughs, particularly because there seem to be so many more of them.

AFAIK, a significant number of commonly carried defensive loads UNDER-penetrate. Of the ones that overpenetrate, few are JHPs. I am certainly open to your quoting results which indicate otherwise.

I certainly agree that the idea of over penetration is exaggerated. But yes, I have seen some rounds go through gel without expanding and some expanding at the very tail end of the gel, almost passing through. That is a manufacturing issue, but it's not like people aren't buying those or else they would have wouldn't have an ammunition company.

I have never been one to believe in over penetration with JHP or FMJ, might make me seem crazy but that is just how I feel. But there are people, and a lot of them, that are terrified of over penetration.

But considering that most healthy people have a center mass of no more than 13 inches deep, it almost seems like some bullets penetrate way too far and that can be scary to some people. As you said, few JHP rounds over penetrate but the idea that ANY do and considering they are designed not too is kind of the reason I posted. JHP are not some sort of magical bullet that just stop exactly where you want them too. Would you agree?

Certainly JHPs are not magic even in ballistic gelatin, less so in human or canine bodies. The FBI is to be commended for attempting to determine their performance with certain frequently-encountered human body coverings.

Marksmanship under stress seems to me to be a greater variable than terminal ballistics. Neither one is guaranteed.

The last figures we had here from the U.S. Justice Dept said 70+% of all rounds fired by law enforcement missed. Which is worse, fear of possible over penetration or an AIR BALL??

Massad Ayoob: The Dangers of Over-Penetrating Bullets | Gun Digest

The central problem with all these tests is that, in dramatic contrast to a block of gelatine, the human body offers an almost infinite number of variables that promote or inhibit penetration.

A few years ago I and a few friends got into a discussion about this at a social event with a guy who was an MD and pathologist. He got out his laptop and showed us some 3D modeling. At a certain direction and angle, a bullet could zip through center mass without touching any bone and exit with comparatively little loss of energy ("overpenetrate"). Move the point of impact or even just the angle of impact an inch sideways, and suddenly there are multiple ribs in the path that increase resistance several-fold. Take a sideways shot that first goes through a limb (like the infamous Miami 9mm round), and suddenly it does not penetrate far enough.

Simply put, a round with sufficient penetration for all anticipated circumstances will inevitably overpenetrate in some situations. Any round designed to never overpenetrate will not go deep enough in some situations.

Anyone who thinks he can derive definite answers about better or worse, or safer and less safe, defense rounds by comparing whether they penetrate an inch more or less in a controlled medium is seeking false reassurance.

As already said, accuracy is a much more controllable factor than bullet behavior. It's probably more beneficial to focus on that.

My opinion, for what it's worth, is that overpenetration IS a concern. Can it happen with JHP? Sure, it can. But it's a lot more likely with FMJ. I've posted this article before. It's an older article with a bad title but it explains why NYPD switched from 9mm FMJ to JHP:

NEW YORK POLICE WILL START USING DEADLIER BULLETS - The New York Times

A relevant passage:

One thing to keep in mind is that this article was written in 1998 and JHP technology has advanced quite a bit since then.

Another factor is that JHP has reduced potential for ricochet. The open mouth is more likely to dig into objects than FMJ. Can JHP ricochet? Sure. But again, it's less likely to do that than FMJ.

This is aside from the terminal ballistics. FMJ tend to make narrow wound channels that, because of the elastic nature of flesh, tend to close back up. A JHP that expands will cause more trauma and increase the likelihood of stopping an attacker. Even if a JHP doesn't expand, the open mouth is more likely to create a cookie-cutter effect than FMJ.

Another thing to consider...As JHP expands, it slows down inside the body. In some cases the expanded JHP exited the body but was stopped by the attacker's clothing. In other cases the JHP exited the attacker's body but fell onto the ground a few feet behind the attacker. In other words, even if a JHP does exit, it's far less likely to have enough retained energy to cause injury or death than FMJ.

As for the gel results, people keep assuming that distances in gel is equal to distances in people. It's not. The 12"-18" gel penetration the FBI recommends doesn't mean 12"-18" in people. People are not made of gel. People have skin, muscle, bone, etc. The FBI recommendation means that expanding ammo that penetrates 12"-18" in gel will generally penetrate deep enough in an attacker's body to disrupt organs, blood vessels, etc., and incapacitate the attacker quickly.

Does JHP performance make up for poor marksmanship? Of course not. That's a really silly argument. I practice in order to get good, quick hits on target. If I can shoot as well with JHP as FMJ, why not use JHP?

"But JHP are less reliable." If your gun doesn't function reliably with JHP, you either need to try different JHP, get your gun fixed, or get a different gun.

For these reasons I would not use FMJ as a self-defense/carry round except for extreme circumstances (i.e., JHP is prohibited, FMJ is the only ammo available, etc.). Others can do what they want.

For me I researched the internet for the best hollow points for my gun and made a decision from there. Check out the link below and take a look and the YouTube channel Shooting the Bull. He tests every kind of ammo from his carry handgun. The results you get from a full size handgun will be a lot different than that of a small barrel carry gun. I only carry Federal HST ammo and happy with that choice.

http://www.luckygunner.com/labs/self...llistic-tests/

In the case of the 9mm ammo, I have had the 115gr GD HP at;
1227-1288...... 61fps
1189-1208......19fps
1120-1165......45fps
#1 45fps in the last load can cause the bullet to not open up, if the low fps happens.
#2 some bullets have a harder copper jacket which can cause over penetration.
3. In HP bullets, in a 4G test, the tip can clog, causing over penetration/

#4 these test are in Gel, not a human body with skin and bones.
Gel is nice to see what happens but it is a different world on the real thing.
If your round has to penetrate an out stretched hand (palm)
and then a forearm before even getting to the body, is over penetration bad ?

Later.

First let me tell you my credentials before I go shooting off my mouth. Retired Police Sgt and FBI trained and certified in the following: Advanced firearms Training, Firearms Instructor, SWAT, and SWAT sniper. Almost any LEO will agree that over penetration is a big concern. The shape of the bullet isn't always going to tell you about penetration. A jhp will over penetrate if it is too powerful. I carry jhp rounds but they are not so fast that I worry about OP. I stick with slow moving big bore (45acp and Colt and 44 special) rounds that are around 200 gr and around 850/1000 FPS. Of course there is a chance of OP with these rounds but the bullet would probably slow down enough that it won't be a threat. When I carry a 357 I stick with Gold Dot ammo at 980 FPS. I'm confident in Gold Dots ability to expabd and not pass through. I have Gold Dot ammo for my other big bores also. You are correct to be concerned about OP in your carry ammo. What may be good for hunting may not be good for personal protection.

Any round that passes through an object and strikes an unintended target is a miss. I am with others on the forum in that I think a person should be proficient enough to hit his target or do not make that trigger press. I of all people understand the excitement of a shoot out BUT here where I live a man was shot at by several officers and hit once in the ankle by a bounced bullet from under a car. They picked up 47 pieces of LE brass. I have several LEs that come here, they range from miserable to OK. NONE have passed the simple 5 shot Wizard Drill.

Buy Federal HSTs and don't worry about it

It's not always center mass of 13 inches deep. Sometimes people stand at an angle. Some are fatter and so.e are more muscular. The minimum is 12 because of that. Add into it bones, which gel doesn't have

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I'm in LE and unlike Topsarge I don't believe overpenetration is an issue.

The real issue is the vast majority of rounds fired in real world gun fights are flat out misses. These rounds go downrange with full power. These are the rounds to worry about.