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Old November 9, 2009, 05:18 PM   #1
savage1r
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Explosives as propellant?

Just throwing an idea out there, I had it a while ago after reading a book where a special forces guy used to take 7.62x39 rounds (in vietnam) and load them in dropped enemy AK's so that when another baddie picked it up to shoot it, the round would explode and send the bolt through the back of the receiver and into the bad guy. But what if you used a very small amount of C4? Would you be able to create a short cartridge for a large bullet and save on space and weight by using a small amount of C4 which produced the same amount of explosive power as smokeless powder?
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Old November 9, 2009, 05:40 PM   #2
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C4 is weird stuff, I would not trust it in a gun.

You can burn it for heat but as soon as an electrical charge hits it...BOOM

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Old November 9, 2009, 05:56 PM   #3
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That is some powerfull stuff . what we used to do was roll up a piece the size of a small marble and lite it . we would then tell a green recruit to stomp it out . KABOOM . they almost always ****** their pants . Damn I miss the 70's.
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Old November 9, 2009, 06:04 PM   #4
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Gun powder is an explosive. It has a low brisance, meaning it is not comsumed as fast. The wave produced is subsonic. What you are talking about is a high explosive with a fast brisance and a supersonic blast wave. That will not be contained in a firearm. I believe the shock wave of the detonation will destroy any firearm
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Old November 9, 2009, 06:04 PM   #5
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Gun propellants technically burn, very fast, but still in a well timed process. Explosives usually detonate, driven by the (supersonic) shockwave. The burn process continues after the bullet has started to move down the barrel, giving you a long but relatively mild push. The explosive generates all its gas basically at once, before the bullet has a chance to move. If you keep the amount of explosive small enough to stay within the confines of allowable pressures, you don't get much energy transferred to the bullet. If you want the same power you get from a regular propellant, you blow up the gun, or need an artillery piece size action.
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Old November 9, 2009, 06:41 PM   #6
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C4 has a higher brisance(burns faster ) rate then gun powder .under preasure it will explode .http://www.experiencefestival.com/a/Brisance/id/1938637
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Old November 9, 2009, 06:48 PM   #7
Brian Pfleuger
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Quote:
Gun powder is an explosive. It has a low brisance, meaning it is not comsumed as fast. The wave produced is subsonic. What you are talking about is a high explosive with a fast brisance and a supersonic blast wave. That will not be contained in a firearm. I believe the shock wave of the detonation will destroy any firearm

Gun powder is technically not an explosive, and the shockwave produced by contained gunpowder is far beyond supersonic. It has to be, otherwise the bullet would not/could not be.

That said, C4 and other true "explosives" burn MUCH MUCH faster than gunpowder.... the bullet would not have time to start moving and the pressure would build "instantly" to catastrophic levels. The gun would explode, exactly like it does with gunpowder and a blocked barrel. The reason that gunpowder does not normally blow up a gun is because it's relatively slow burn rate allows for the bullet to begin moving ahead of the expanding gases, keeping pressure at safe(r) levels.
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Old November 9, 2009, 07:18 PM   #8
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Quote:
Gun powder is technically not an explosive, and the shockwave produced by contained gunpowder is far beyond supersonic.

Actually, yes it is. A low order explosive. Many of those charictaristics are only represented in containment.


Chemical definition of an explosive:

A substance that decomposes rapidly under certain conditions with the production of gases, which expand by the heat of the reaction. The energy released is used in firearms, blasting, and rocket propulsion.

Note the, "decomposes rapidly under certain conditions". In the case of a firearm those conditions are being contained. Containment provides " heat of the reaction" conditions to take place. In open air smokeless gunpowder acts as a rapid flamable solid, but in containment it is a low order explosive.
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Old November 9, 2009, 07:28 PM   #9
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Ok forgive my spelling.

But Gun powder (smokeless) is an high explosive, Black powder is a low explosive. (defined by the burning rate).

All explosives burn. The controled burn, in the barrel gives us the prepellant. But gun power is either double or single based. Meaning either NItorcilious & Nigroglision, or single based Nitocilious or gun cotton.

The primer starts it burning, it dosnt explode in the gun. If it burns too fast it can, just as using a case full of bulleyes pistol power in a rifle. Its gonna burn TOO FAST.

You take a can of gun powder, and put a blasting cap it it, it explodes.

You take c-4 and put it in a case, it burns, it burns fast, but it dosnt go high order.

We've played around like this when I was on the Bomb Squad, but WARNING, THIS WAS CONTROLED EXPERIMENTS.

Dont try it, one of my duties was policing up fingers and other assorted body parts from people playing games with explosives and gun powder.

Ever heard the term DONT TRY THIS AT HOME. It mean what it says.
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Old November 9, 2009, 07:41 PM   #10
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c4 was designed to cut/shatter steel.

i was a combat engineer for 7yrs, many stories on c4.

and contrary to popular belief, electricity will NOT detonate c4. neither will a tracer, fired from any caliber including .50 bmg.

a pea sized peice will boil a 1/2 canteen cup of water.

and a small bit on the knife you use to open your mre will give you bad diarrhea.

ammonium nitrate MAY work, it is a "pushing" explosive, unlike a "shattering" explosive like c4.
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Old November 9, 2009, 08:13 PM   #11
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Quote:
and the shockwave produced by contained gunpowder is far beyond supersonic. It has to be, otherwise the bullet would not/could not be.
Actually, the bullet may well be subsonic to the super hot gasses pushing it. The hotter a gas is, the faster the speed of sound is. The speed of sound is proportional to the square root of the absolute temperature so if you heat air to 2000 degrees, sound will go about 2580 fps. Heat air to 3000 degrees F and sound goes about 2800 fps
How hot are the gasses that propel the bullet? I really don't know but I suspect that the speed of sound of those superheated gasses is what places the upper barrier on how fast bullets can be driven out of a gun.

A gun powder explosion is like hitting a bowling pin with a bowling ball, the pin goes flying but the ball does almost no damage to it.

A C-4 explosion is like hitting a bowling pin with a bullet from a .220 Swift. The bullet goes through the bowling pin and does extreme damage and yet just barely tips it over.
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Old November 9, 2009, 08:15 PM   #12
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Doesn't C4 require a cap. One that uses an initiator and booster. Like a fulminate igniter and a picric booster.
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Old November 9, 2009, 09:00 PM   #13
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This is interesting. The last time I inquired about buying some dynamite which was years ago the dealer had different grades rated at feet per second. We blew stumps out with it when I was a young man.


http://nobombs.net/brucel/explosivefacts.html
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Old November 9, 2009, 10:25 PM   #14
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Quote:
Originally Posted by Kraigwy
But Gun powder (smokeless) is an high explosive, Black powder is a low explosive. (defined by the burning rate).
High explosives detonate. Gun powders (low explosives) deflagrate when ignited or set off. Containment is required in order to cause an explosion.

Quote:
But gun power is either double or single based. Meaning either NItorcilious & Nigroglision, or single based Nitocilious or gun cotton.
Just to pick nits - it's nitrocellulose. Double-base gun powders are a bit more stable over time than singlebased types.

Quote:
You take a can of gun powder, and put a blasting cap it it, it explodes.
Of course. Because a blasting cap is a small amount of "high explosive" and detonates.

C4 or Comp-4 is a reformulation of RDX to blend it with plasticizers and other materials to make it stable and malleable like modelling clay. It is quite stable until it is put under a large shock-load (like a blasting cap).

Rumors of soldiers spiking AK rounds with C4 are probably true to some extent. I know of one SF solider who used Comp-B from a grenade to spike about 60 rounds of 7.62x39 ammo, some of it in MG links. Since it was "free", the tendency was to fill the brass case about 3/4 full and reseat the bullet, carefully crimping with a wire crimper or fuse crimper.

Could you use C4? Perhaps. But since C4 is really an explosive there is a chance that a primer's ignition could create enough shock in an enclosed space to begin detonation.

As a primer - detonation occurs when a material burns faster than Mach 1 (1138 fps). Most gunpowders - black or smokeless - are much slower than that. When C4 detonates, its burn rate is approximately 26,400 feet/sec.! You'd need an artillery breech to contain the pressure.
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Old November 9, 2009, 10:52 PM   #15
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Why not just use established DOT definitions?

Black powder is an explosive. So are primers (and most fireworks)

Smokeless powder is a flammable solid.

The primary problem with using an explosive in a cartridge (rather than the usual propellant) is breech pressure. Explosives tend to be a all at once thing, and explosives also tend to be ...less stable than propellant powders.

I suppose you could design a very small case to hold a very small amount of explosive, but what would be gained? You are limited to the same approximate pressures as those obtained from gunpowder (at least as long as you continue to use brass cases for obduration), so, what's the point?
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Old November 9, 2009, 10:57 PM   #16
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question

A question about RDX and its relation to smokeless propellants.
I had an experience at JFK airport some years ago - after 9/11 - that prompts my question. Is RDX chemically related to either single or double based propellants?
I was using an old backpack for a carry on. It had been used at one time as a range bag. I had not used it for a while and had washed and cleaned it.
Going through security, it attracted attention. The person in charge told me that they had found traces of RDX in the bag. I assume that the traces were bits of unburned smokeless that had not been washed out.
The whole scene worked out amicably. I don't carry the bag any more.
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Old November 10, 2009, 07:02 AM   #17
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Nearly all common explosives and propellants are some form of nitrated organic compounds. These give very distinct patterns in a mass spectrometer as used in those wipe-down machines at airports. The RDX identification was simply the closest match to the pattern the machine saw, doesn't mean it actually found RDX.
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Old November 10, 2009, 09:37 AM   #18
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What about a lower order explosive agent, like gasoline? Is is possible to make a cartridge that used gasoline, kerosene or diesel fuel to propell a projectile in a pistol or rifle? I've often wondered if this could be used if it ever became impossible to obtain modern gun powder or even black powder.
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Old November 10, 2009, 10:48 AM   #19
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You take a can of gun powder, and put a blasting cap it it, it explodes.
Only from the cap.

The shipping test for flammable solids (like smokeless powder) requires cases of powder packaged for regular shipping to be stacked.

A blasting cap is placed in the middle box in a middle can of smokeless.

There can be NO detonation or the material must be shipped as an explosive.

The flash from a cap is to short to adequately ignite a large quantity of smokeless before the primary blast pushes most of the powder away.

There is a huge difference between true explosives that detonate without confinement of any type.

Even a pipe bomb made with smokeless will not detonate, but creates a pressure burst failure of the container.

This is very different than a true detonating explosive.
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Old November 10, 2009, 12:28 PM   #20
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And just to add to the confusion, the reason a low charge of smokeless powder can destroy a gun is that the primer explosion doesn't start a controlled burn of the powder column but generates a air-powder explosive by mixing the small powder charge with the air in the cartridge. This leadsto a much more rapid release of energy than would be the case with a controlled burn process.
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Old November 10, 2009, 01:29 PM   #21
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What about a lower order explosive agent, like gasoline?
Gasoline is not a lower order explosive.
imho it's one of those things which can work but are not as effective as other alternatives. What makes gas work in your engine is that it's vaporized making a mini fuel air explosion. It would be possible to do something similar behind a projectile but not in self contained cartridges. At least not cartridges that would be usable in shoulder arms. You would have to build a different kind of mechanism.

It is possible to make black powder in your garage and probably some of the nitrocellulose powders. Not sure if home made primers are a possibility though.

I kind of doubt that you have to worry about it anyway. Besides if Red Dawn happens in your neighborhood, it's much better to think in terms of IEDs than firearms.
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Old November 10, 2009, 01:55 PM   #22
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Gasoline is not a lower order explosive.
imho it's one of those things which can work but are not as effective as other alternatives. What makes gas work in your engine is that it's vaporized making a mini fuel air explosion. It would be possible to do something similar behind a projectile but not in self contained cartridges. At least not cartridges that would be usable in shoulder arms. You would have to build a different kind of mechanism.
My thought would be to use some substance similar to cotten which could then be soaked in Diesel fuel and stuff that into a cartridge. Then place very thin and small balloon filled with O2 into the cartridge as well, and use a large primer to burst the balloon and ignite the O2/Diesel mixture. I think it could work, but I don't know how a diesel/O2 mixture compares with modern gunpowder.
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Old November 10, 2009, 02:09 PM   #23
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Skans there's a couple problems with your idea. 1 the balloon would have to be resistant to the corrosive effects of the petrolium. 2. the balloon would have to be capable of holding air for an extended time without deflating. 3. what makes gas explosive is its vaporization. If the fuel was soaked into cotton then it wouldn't vaporize very well. 4. If we have to MacGyver propellant then there will probably not be primers readily available.

I think we would have to look at something similar to a CO2 pellet gun with pressurized gas and O2 tanks and some form of ignition such as a piezoelectric spark.
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Old November 10, 2009, 02:51 PM   #24
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With some the high powered air rifles that air can combust (2000 psi tends to do that)
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Old November 10, 2009, 03:04 PM   #25
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Sorry, air cannot combust, nothing combustible in it. What you are referring to is oil in the air rifle combusting under high pressure (basically a mini Diesel engine).
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