is it true, or just myth?

Status
Not open for further replies.
tark said:
It was a factory Federal 230 grain hardball round. There was no powder left in the case. I have no idea what or how this happened. I am still so dumbfounded by this whole thing that my eyes are still crossed.

I must say again that Julian Hatcher did this exact same test on a 1903 Springfield with a standard G.I. Ball round, with the exact same results, No damage to the gun!! I have no idea how on earth this could be.

When I first challenged Jim K with the statement that I was going to try this, I expected him to immediately start back-pedaling and hemming and hawing and stalling. What he did was request a PM from me, and then he gave me exact details on how to set this up and what he did. I got a set of very exacting directions. I was really wondering at this point. I thought, "this guy is really serious"

So I followed his directions and he was proved right. All I can think of is this: If the bullet never moves, the combustion process must somehow be interrupted, with the result that it never really gets started.... Hell, I don't know..

All I know is that it goes down exactly as Jim K said it would. I learned something new. At 68....still learning.
Click to expand...
Well since it seemed to work, video it and put it on Youtube for all to see.

Deaf
 
I do not go near U-tube Deaf. Had a bad experience. All of the social media is stupid in my book.

Threading the barrel was a you know what. Colt barrel, Damned hard. My tap at home wouldn't bite into it so I took it to my old shop and threaded it with a quality tap..

Primer looked normal.

When Jim first talked about doing this he asked how many of us had actually tried it. A valid question, I figured he was bluffing and that I would call his bluff. All I did was prove him right.
 
So you ended up with an empty shell that still had the bullet in it and a fired primer? Outstanding and yet utterly bizarre!
 
Primer looked normal
Click to expand...

First off....thank you very much for this test! Super interesting stuff!!:)

I'm amazed that the primer looked normal....which I believe is indicating that when the bullet is prevented from moving that the powder does NOT burn as it normally would. If it burned normally the blocked bullet should have increased the pressure...at least enough to flatten or distort the primer I'd think. We've fired 45's that showed no primer indent afterwards or even extruded into the primer channel to be nipped off when the barrel dropped during unlocking...so this tells me the pressures just weren't that high in the test....which is amazing!

There has GOT to be some logical explanation for why the primer isn't showing pressure signs but my ignorance is preventing me from thinking about one. Let this be an excellent lesson to us all that what we 'think' will happen is sometimes NOT what will! I won't rest easily until I either find the explanation for the lack of pressure being created here or someone else comes up with the answer.

Now...the next question: is this phenomenon only valid in 45 ACP...or will many other rounds act the same way when blocked in the chamber? Remembering Ruger P-85 test where they blocked the round in pretty much the same way (though I believe it could move .015" and the rod was not contoured to the bullet nose) and it blew out the case under the extractor...so excessive pressure WAS created in their case. Why oh why isn't that happening here?:)
 
Could the (fully burned) powder near the primer have created enough pressure, that somehow it was able to slow down the reaction?

If you spread the powder out on a flat plate, it would just burn up, no explosion.

Since you didn't get an explosion, the powder may have burned, but didn't "explode". Since you had a sealed container, the pressure must have started to increase - but maybe at some point, it stopped? Too bad you couldn't have had a pressure gauge in the gun.

If you ever do this again, maybe you can put something between the bullet and the bolt, maybe lead, and see how much it compresses. Anything to measure the force.
 
All I can think of is this: With the bullet immobile the combustion process is nipped in the bud, so to speak, before it ever gets started. I have been told that if the bullet starts to move, even the slightest bit, the whole thing blows up. This is the only explanation I can come up with.

Some useful info may be gleaned from Hatcher's Notebook, third edition, page 187. I don't have a copy (a glaring omission in my library) but Jim K was kind enough to provide the info. Hatcher apparently did the same test with a Springfield rifle and a G.I. Ball round. He used a steel rod to render the bullet immovable and he got the same results. Nothing happened!

The Dark Side of the Force has got to have some influence in this! That, or we will just have to blame it on George Bush:what:
 
Unless the casing was filled to where the bullet sat, there already was some room for expansion - but not much. If the bullet moved 1/64th of an inch, I think you'd get the same result you got, as the "explosion" got stopped so soon. If there was a one inch gap between the bullet and the bolt you put in, I think you might now be searching for bits and pieces...
 
The chemical combustion process is NOT stopped by the pressure. And, in fact, objective evidence provided by tark in post #98 shows that combustion was complete and no unburned powder was left:

"There was no powder left in the case."

That being the case, and physics being what it is, then the answer(s) to the question as to what happened with the gases/pressure boils down to understanding exothermic chemical reactions, Boyle's law, and just plain physical construction of the material used for the test.

It is an established fact that:

1. Total combustion of the powder occurred.

2. The gun suffered no apparent plastic deformation during the test.

3. Pressure was not retained in the gun after powder combustion.


Therefore the pressure within the chamber dropped as the result of one or more factors:

1. Leakage, which could have happened through several means: between the bullet/casing and down the barrel, between the bullet casing back along the chamber towards the rear, between the primer and casing.

2. Cooling down of the gases, by convection/conduction heat transfer means to the metal parts of the gun, which would cause pressure to drop.


It is worth noting that the components in question are NOT designed to be hermetically sealed. In fact, during ignition of the primer, the bullet casing will first expand to fit tightly in the firing chamber, then relax again, loosening the "seal". The bullet does not form a hermetic seal with the barrel riflings.
 
I won't even try to answer all those comments, but there was no effort made to "contain" the gas. The normal operation of the 1911 is by recoil from the moving bullet, not directly from gas pressure. If the bullet does not move, there is no recoil.

Full powder combustion takes place, it is not "stopped"; the gas produced simply leaks away, but slowly enough that it has no effect on the operation of the gun.

Jim
 
The-Hurt-Locker-the-hurt-locker-12026210-1200-674.jpg

FOR SCIENCE! :D

So, was there even a hiss/etc you could discern (I understand you weren't right next to the thing)?

Primer damage? (I would think it would occur simply due to heat load in the thin primer metal given enough time sitting there after ignition)
Case head damage, other pressure signs? (Same theory re: heat load due to sustained pressure)

Powder residue? One wrinkle that could come into play is whether powder NEEDS an increasing volume to burn correctly --seems reasonable to me, seeing as it's been carefully optimized to drive a bullet this way. A clean burn would suggest proper combustion efficiency, black sooty deposits the opposite (like running magnum powder through low pressure pistol loads)

Did the gun pop like a cork when you opened it? Just how long did you wait for pressure to normalize, to avoid ^^^^^^? :D

TCB
 
If I was taking that photo up above, I'd like to think I would be smart enough to forget the photo and get as low as possible as fast as possible.... Excellent photography - hope the photographer lived through it.
 
Unless the casing was filled to where the bullet sat, there already was some room for expansion - but not much. If the bullet moved 1/64th of an inch, I think you'd get the same result you got, as the "explosion" got stopped so soon. If there was a one inch gap between the bullet and the bolt you put in, I think you might now be searching for bits and pieces...
Click to expand...
"Explosions" or any expanding thermal process becomes weaker as its volume increases due to thermodynamic conservation (I forget, but it's like a cubic or quartic function; very rapid declines). The reason a squib halfway down the barrel is so destructive is that same thermo conservation imparts an enormous amount of energy to the projectile (which is the point, after all). Unlike an explosion/conflagration/etc spread out all over the inside walls of the barrel and acting in all directions, the bullet is an incredibly focused, highly energetic element (again, the point of the whole device).

Stopping the pressure peak inside the case, even at extraordinary levels due to a stuck bullet: doable

Stopping a speeding bullet cold as it crashes into a rigid object and directs all that momentum outward against the sides of the barrel: not a chance.

Here's another way to think of it: what happens when you shoot a bullet (any bullet) at the side of an identical barrel? Because that's basically what happens if you give a speeding bullet no avenue of escape from inside a gun barrel ;)

TCB
 
If I was taking that photo up above, I'd like to think I would be smart enough to forget the photo and get as low as possible as fast as possible.... Excellent photography - hope the photographer lived through it.
Click to expand...
What, that terrible Hurt Locker movie, or the nuclear test that appears to have warships engulfed in it? :p
 
Aha! So that's where that photo came from. I got fooled. :)

The other photo was real - after WW II, they anchored a fleet of ships in Bikini Harbor, and set off a nuclear weapon to see what would happen. Those tiny ships are full size American and Japanese ships, at varying distances from the bomb. After the bomb went off, they analyzed the amount of radiation, and the damage.
 
From the internet:

"the ignited propellant (gunpowder) exerts a powerful force on the gun."

So, if the full force from the powder exploding should have wrecked the gun, and that didn't happen, the force must either have been lower, or taken a longer time. Therefore, the powder most likely didn't burn the way it normally does. Maybe it burned more slowly, or maybe it didn't burn as completely as it normally does, even though all of it looks burned.
 
"...and radiation" and made Bikini uninhabitable until a few years ago --oops.

"So, if the full force from the powder exploding should have wrecked the gun, and that didn't happen, the force must either have been lower, or taken a longer time."

The hypothesis was the high pressure of a stopped charge would pop the gun like a squib; that didn't happen, so the hypothesis needs to change, not the creation of a second hypothesis to explain the first's failure ;)

TCB
 
I made it all the way through Hatchers Notebook section on bore obstructions, and his experiments with full power 30 caliber rounds blocked similarly to what Tark and Jim have done resulted in no explosions though the case DID contain a dark tar-like goo afterwards which pretty conclusively showed that the powder did NOT burn properly in a totally contained space...at least in that example.

The various ringed barrels or total blow-ups were caused by the kinetic energy of a moving bullet being redirected sideways by the blockage, at least that was the conclusion he came to. In this case, if the primer doesn't show signs of excessive pressure...then I'd opine that none was created.

Ultimately the answer would be illuminated by a strain gauge on the chamber while doing the experiment and I'd be surprised if even normal pressure was created. If the bullet can't get moving, then no kinetic energy is created so ALL of the potential power within the powder must go straight into heat. There very well might be some mechanism within the powder chemistry that won't allow it to detonate and by the time the pressure rises to the point of nastiness the heat transfer is so great that it can't continue. Thinking that the chamber temperature would be much greater on the test gun, shot for shot, than a normally fired one if this theory holds true. Still...a VERY thought provoking demonstration! Well done men.:)
 
mikemyers said:
From the internet:

"the ignited propellant (gunpowder) exerts a powerful force on the gun."

So, if the full force from the powder exploding should have wrecked the gun, and that didn't happen, the force must either have been lower, or taken a longer time. Therefore, the powder most likely didn't burn the way it normally does. Maybe it burned more slowly, or maybe it didn't burn as completely as it normally does, even though all of it looks burned.
Click to expand...

No.

More likely, the 6 or 7 grains of factory powder did not produce sufficient force to exceed the fracture toughness coefficient of the steel used to fabricate the barrel, or even enough to cause plastic deformation of the steel.

The powder obviously burned completely, as noted in post #98. Since the chemical reaction is only dependent upon the chemical constituents making up the powder and not upon outside factors such as atmospheric Oxygen, and since the chemical reaction is initiated by heat produced by the primer ignition, and since a rapid increase in pressure within the enclosed space will necessarily cause another temperature spike, there is no reason whatsoever to believe that the conditions would have caused the chemical reaction to proceed at a lower rate.

;)
 
If "the 6 or 7 grains of factory powder did not produce sufficient force to exceed the fracture toughness coefficient of the steel used to fabricate the barrel" .....then where did the extra energy come from that might have blown the gun apart if the barrel was blocked?

I'm assuming that with a barrel blocked, the gun would have blown apart. Maybe Tark needs to re-do the test, this time with the bolt only half way into the barrel. Perhaps he would get the exact same result as he did in the test.



Right now, we're only comparing what DID happen, because the bullet couldn't move, to what we THINK would happen if the bullet was allowed to get up to speed.

In Tark's test, we're looking at what damage the bullet might do to the actual gun. If the bolt was shorter, the energy might also be trying to "bulge" the barrel.



If you are correct that in both scenarios, the powder burns "normally", then it will release the same amount of energy in both scenarios.
 
mikemyers said:
If "the 6 or 7 grains of factory powder did not produce sufficient force to exceed the fracture toughness coefficient of the steel used to fabricate the barrel" .....then where did the extra energy come from that might have blown the gun apart if the barrel was blocked?

I'm assuming that with a barrel blocked, the gun would have blown apart. Maybe Tark needs to re-do the test, this time with the bolt only half way into the barrel. Perhaps he would get the exact same result as he did in the test.



Right now, we're only comparing what DID happen, because the bullet couldn't move, to what we THINK would happen if the bullet was allowed to get up to speed.

In Tark's test, we're looking at what damage the bullet might do to the actual gun. If the bolt was shorter, the energy might also be trying to "bulge" the barrel.



If you are correct that in both scenarios, the powder burns "normally", then it will release the same amount of energy in both scenarios.
Click to expand...

That's a good question.

The usual assumption is that something similar to this test occurs when the barrel is blocked by some obstruction, such as a squib or foreign object. Like what you're talking about.

The answer is that it comes from momentum transfer from a moving bullet of some mass.

Also, remember that the firing chamber region is a bit thicker than the barrel itself.

There are plenty of instances where firing a gun after a squib has occurred which didn't cause any apparent damage. Likewise, we've likely seen pictures where firing a gun after a squib DID cause damage.


An easy way for tark to check this would be to simulate a squib by pressing a bullet some length down the barrel and repeat the experiment.
 
I can't contain myself ...

"I have from more than one source that if you render the bullet immovable, in a 1911, by whatever means, no damage will happen to the gun, when fired, and it will slowly bleed off the pressure."


The way I heard it was: if you plug the barrel with Georgia red clay, and immerse the pistol in a Florida swamp for three days, that no kaboom will occur upon firing it. I know this is true, because my second cousin...

Who comes up with this BS, anyway??? God help us.
 
Though it seems to not be an issue here (evidenced by the clean burn) I suppose it's possible that a larger charge like in a rifle could be retarded by the fixed volume; after all, the combustion products do not chemically contribute to powder burn, so for all we know, condensing them enough might actually snuff the burning granules out. I would think such an effect would be more pronounced in slower (rifle) powders.

But for sake of what we know so far, let's assume the burn, and therefore energy released, is a fixed quantity.

Would exploding gunpowder accelerating the bullet down the barrel be the same as the energy released in Tark's test?
Click to expand...

Because powder acts on the walls and breechface in addition to the bullet, and because the gas will still be expanding even after the bullet leaves the gun, and because the gas itself is accelerated greatly, the energy imparted to the bullet will be less than the heat generated. The difference between them will be small, though, especially if we treat the gun as 'fixed' and unable to recoil (bolt action pistol in a vise, for arguement's sake). Lets assume these losses are negligible, compared to the juice required to blow the gun up.

The difference between the energy being evolved purely as heat/pressure inside the chamber and as a moving bullet has to do with their concentration or focus. The whole purpose of a gun is to direct the pressure generated by gunpowder into a single, focused element, very much like how a laser collimates photons into a beam. For the fixed bullet, that energy appears and seeps outward into the metal walls as heat; there is a certain rate of transfer associated with this process, and it does not happen instantaneously.

When the moving bullet hits the object and splatters sideways, it delivers force & heat directly to the walls almost instantly. At least compared to the spike of pressure & heat at the chamber (otherwise we'd get awesome velocities from <1" barrels). The process is so much faster and impacts such a smaller contact area than the powder burn in the chamber, that it exceeds the metal's ability to resist or dissipate the energy, so it deforms.

Put (don't) a charge of blank/flash powder of the same chemical energy as the standard 45acp load behind the stuck bullet, and you're more likely to get the kaboom you're looking for. A true high explosive like RDX would be even more dramatic since the impact of its detonation wave against the chamber walls would more closely mimic that of the speeding lead against a squib.

TCB
 
Status
Not open for further replies.

Similar threads

A
  • Locked
+P Ammo in a Glock or XD
Replies
13
Views
627
PO2Hammer
PO2Hammer
T
  • Locked
True Blue and Lead Bullets in 357
Replies
1
Views
616
tkcomer
T
T
  • Locked
Copy of email from Ram shot 380 and true blue powder
Replies
0
Views
513
tackstrp
T
J
  • Locked
.410 O/U choke measuremets
Replies
1
Views
491
jrfoxx
J
C
  • Locked
Timothy Egan: Myth of the Hero Gunslinger...Or, rather, the Myth of Good Journalism
Replies
7
Views
727
earlthegoat2
earlthegoat2
Back
Top