FMJ Ball For Self Defense?

[JoeG]

Ummm ... in a word ... no. There is no "shedding" of energy or "imparting" of energy to a body. Energy is only used. In the case of FMJ, no energy is used aside from that used to penetrate. JHP ammo does not dump, shed or impart energy. It simply uses energy to penetrate and possibly expand. Expansion causes a bigger wound track, but results in - comparatively - little loss of energy as a result ... assuming we are talking about the standard kinds of duty/defense loads in common use.

Almost any bullet which over-penetrates retains enough energy to injure/wound/kill another person. The physics are such that almost any case of an FMJ over-penetrating would over-penetrate with an analogous JHP as well. The danger of over-penetration is almost (statistically speaking) mythological in comparison to the documented danger of failing to hit what you are shooting at. A flyer or miss represents a much greater chance of killing an innocent.

The original intent of HP designs was indeed an attempt to make "safer bullets". It just didn't work out that way. Any  design which potentially expands enough (with a given amount of energy) while not over-penetrating, does so with the trade off of not penetrating sufficiently when expanded. Any round which meets FBI standards for expansion/penetration does so with the trade off that it will in fact over-penetrate in a high percentage of cases. That's just how the physics work out.

At any rate, JHP designs do not expand as reliably as many think in real-world shootings. You often end up with essentially a FMJ anyway. The choice to use JHP should based upon the potential of larger wounds, not on any false notions regarding the dangers of over-penetration.

I don't usually quote full posts but this is utter nonsense and dangerously wrong. As an engineer who has spent time reading the peer reviewed literature there is almost nothing in this post that does not contradict the science of ballistics. Go read Mas Ayoob on the real street cases he has reviewed where good guys are injured by pass throughs. this was all settled in the 70's and 80's when LEos quit using FMJ in spite of political pressure against HP ammo.

All bullets lose energy to their surroundings all the time; barrel friction, air resistance and then to whatever they hit.

Think of a bullet hitting a steel plate it DUMPS its energy into the steel plate and knocks it over or if is a 556 it generates enough HEAT to burn a hole through the plate. It is all about friction, surface area and the yield point of the material being hit.

Don't be an arrogant ass, listen to the experts with real world experience and stop carrying FMJ rounds.  If nothing else it it will help you survive the trial after the shooting.

[PegLeg45]

........As an engineer who has spent time reading the peer reviewed literature there is almost nothing in this post that does not contradict the science of ballistics. Go read Mas Ayoob on the real street cases he has reviewed where good guys are injured by pass throughs. this was all settled in the 70's and 80's when LEos quit using FMJ in spite of political pressure against HP ammo.

All bullets lose energy to their surroundings all the time; barrel friction, air resistance and then to whatever they hit.


Think of a bullet hitting a steel plate it DUMPS its energy into the steel plate and knocks it over or if is a 556 it generates enough HEAT to burn a hole through the plate. It is all about friction, surface area and the yield point of the material being hit.

Say what, now?

You had me up to that point. I can agree with your first part about losing energy from the point of ignition onward........but,

2800 degree Fahrenheit .22 bullets melting through?

Lost me there.


A bullet acts for a fraction of a second. Rapid deceleration enhances this force. A bullet's force acts proportionally to how resistant the target is to its forward travel. When a bullet hits steel it starts building force at it's leading edge.... until something yields: Either the plate gets knocked over, or the bullet punches through.

The fact that a bullet may act for only a split second does not discount the tremendous force that can accumulate. The same cannot be said when you are trying to melt something. The faster the work is done the greater the energy needs are.

You would think that a "faster" bullet would be more likely generate "melting" heat. IMO, the fast bullet is actually less likely to transfer heat to a target it will ultimately penetrate because it has even less time to act. It's more like punching a hole in a sheet of tin with a hammer and nail....just with a bullet, the force is applied at a higher rate.

What happens when you shoot into heavy paper, say a phone book. It's clear that high heat is not needed for penetration. I've never set a book on fire with a bullet.

I am vaguely aware of a depleted uranium tipped round that our military has that may generate 'melting heat' when it pierces thick tank armor. But I believe the difference is in the ultra high speed (energy), tremendously dense mass and thick steel. The melting actually does not start till the projectile is well into the thick steel.


Shoot a hole in a steel plate and then go touch the plate immediately after the shot. The plate will not be hot enough to indicate that the hole was melted through. It takes a lot of heat to melt through a plate and a bit of time even with a cutting torch, also remember that the lead melts at a lower temperature than does steel......... so the core of the bullet would be molten and the jacket would split and the lead splatter on impact.  


JMHO.....
I am not a scientist, and I didn't even stay at a Holiday Inn Express last night........
YMMV.  






*Momentum is a bitch, though.

[MikeBjerum]

If a twenty-two caliber bullet traveling at 2,000+ fps were "burning" through the metal wouldn't we see splatter much like you get from a cutting torch or plasma cutter?  When I take my .223/5.56 or .22/250 to steel plates at 100 yards and they punch through, I see a clean hole with metal upset out both front and back.  The upset is sharp with no signs of heat erosion.

Heat = removal of metal
Impact = displacement and distortion of metal

My experience has been impact.

[Timothy]

<<<<< I make a living cutting metal<<<<<<<


Paper burns at 451 degrees (or spontaneously ignites)!  Steel at 2750...

A bullet traveling at any rate of speed will not produce enough energy to melt steel, period.  It's impact energy either punches through or bounces off after expending that energy...besides, brass has a relatively low melting point of around 900-950 degrees.  If there were enough frictional forces to heat a bullet to melt steel, it would melt itself prior to reaching the required temperature if were 100% brass, which it ain't!!!!  It's mostly lead which melts at about 650...  

[Solus]

<<<<< I make a living cutting metal<<<<<<<


Paper burns at 451 degrees (or spontaneously ignites)!  Steel at 2750...

A bullet traveling at any rate of speed will not produce enough energy to melt steel, period.  It's impact energy either punches through or bounces off after expending that energy...besides, brass has a relatively low melting point of around 900-950 degrees.  If there were enough frictional forces to heat a bullet to melt steel, it would melt itself prior to reaching the required temperature if were 100% brass, which it ain't!!!!  It's mostly lead which melts at about 650...  

Oh good..I get to Nit Pik   

It won't bounce off if all the energy is expended..it will fall to the ground... the rebound uses the rest of the energy after it wasn't sufficient to penetrate the target.

Told ya it was nit picking 

[Sponsor]

[Timothy]

Oh good..I get to Nit Pik   

It won't bounce off if all the energy is expended..it will fall to the ground... the rebound uses the rest of the energy after it wasn't sufficient to penetrate the target.

Told ya it was nit picking 

Isaac Newton has his say in all things physical!

 

[tombogan03884]

Oh good..I get to Nit Pik   

It won't bounce off if all the energy is expended..it will fall to the ground... the rebound uses the rest of the energy after it wasn't sufficient to penetrate the target.

Told ya it was nit picking 

Now I'm going to nit pick your nit picking !   

It will bounce off because the bullet has expended all it's energy and has nothing left to counter the combined energies of gravity forcing it toward the ground  and the energy of the metal trying to return to its original position and shape forcing it backwards.
Impact distortion may prevent it from completing the return, but it will exert energy making the attempt .
Similar to the reason machined barrels need "stress relief".

[Solus]

Now I'm going to nit pick your nit picking !    

It will bounce off because the bullet has expended all it's energy and has nothing left to counter the combined energies of gravity forcing it toward the ground  and the energy of the metal trying to return to its original position and shape forcing it backwards.
Impact distortion may prevent it from completing the return, but it will exert energy making the attempt .
Similar to the reason machined barrels need "stress relief".

You may be right...  or maybe right in this special case...  or maybe mine is the special case

What I'm getting at is what would happen if the target was (impossibly) 100% incompressible?  Would the bullet just splatter?  What would happen if the bullet didn't have enough energy to totally splatter itself?  Might drop to the ground.  

I know this doesn't really matter in the overall scheme of things...but I have it as a "thought" problem now.  Any one with enough physics background, add their Nit  

[Timothy]

I recall an episode of Mythbusters where they were doing some experiments shooing into water.  They shot .223/5.56, 30-06, 50 BMG and a few pistol calibers.

All of the really high velocity stuff fragmented to itty bitty pieces when they hit water.  I suspect hitting an impenetrable metallic surface would be much the same. 

[Ichiban]

I don't know if it adds anything to the conversation but it is fun to watch.

Looks like there is a little plasma action going on there.

It would be nice to know the technical background on each shot.