Gurus...Case position sensitivity with powders


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Ex
January 1, 2013, 06:28 PM
We all know that there are many powders out there that are very fine grained, fast burning, and don't fill some cases very far.

I have read that TiteGroup is a powder that is NOT supposed to be position sensitive. I also read somewhere that many of these fine grained powders are position sensitive and can get you into real trouble if, for example, the "fire" starts at the front of the case and not back by the primer. And, that this is called detonation which can cause Kabooms.

Question:
Does anyone have any good info on case position sensitivity and detonations?

Ex

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918v
January 1, 2013, 06:41 PM
I just have personal experience:

TG is position sensitive. It is less position sensitive than Bullseye, though.

Bullseye will detonate if you go below 2 grains under a 148gr HBWC in a 357 case, but there is not enough energy in that 2 grain explosion to harm your 357. It will stick your case in the cylinder and when you pound it out you'll find the exterior pristine (i.e. no evidence of having been fired) and perfectly fireformed to your chamber.

murf
January 1, 2013, 06:50 PM
918v,

does that happen every time, or just on occasion?

i have not had that happen with 2.5 to 3 grains of bullseye in my 357. guess i'm close to the minimum.

murf

918v
January 1, 2013, 06:56 PM
It would happen 50% of the time in my Python for the short amount of time I played with these squib loads. It was also accompanied by an ear-piercing report and FC-100 primers that were melted into the caseheads. Once I increased the powder charge past 2 grains ( I was loading them at the range ), the ear-piercing noise turned into a regular boom and the cases became nice and sooted as they should be.

murf
January 1, 2013, 07:19 PM
sounds like your load went supersonic! did the bullet get stuck in the barrel?

murf

918v
January 1, 2013, 07:22 PM
No, they were clearing the barrel and making it to the target. I wasn't shooting them through a chrony, but I doubt they were supersonic because they did not have any recoil hardly. It was like shooting a cap gun.

rsrocket1
January 1, 2013, 07:37 PM
The bullet didn't go supersonic, but a detonation by definition is supersonic (the wavefront of the explosion goes supersonic). It still generates pressure which will drive the bullet out of the case and luckily for 918v, out the barrel too.

I know Bullseye has a high nitroglycerin content, but was skeptical of how "fast" it is on the burn rate chart. In normal sized charges, it behaves much like Unique. Even in cavernous cases, it seemed to be pretty well behaved. I load 11g behind a 110g plated bullet in .308 for plinking and it behaves almost identically to 11g Unique, Red Dot and Power Pistol.

To the OP, I've chrono'ed a number of loads shooting both normally and with the barrel tipped up between shots and there is a definite difference in velocity and spread when doing one versus the other. Of course dense powders such as Bullseye in big cases like 38/357 make much more of a difference than bulky powders like Unique in 40 S&W.

murf
January 1, 2013, 07:37 PM
didn't mean to steal your post, ex. am interested in the point where deflagration turns into detonation.

murf

243winxb
January 1, 2013, 09:37 PM
http://www.thehighroad.org/showthread.php?t=607180 powder position. http://firearmsid.com/Feature%20Articles/McCord_gunpowder/index.htm detonations, as long as the bullet can move, its not going to detonate.

rcmodel
January 1, 2013, 09:52 PM
Does anyone have any good info on case position sensitivity and detonations?Smokeless powder simple cannot detonate in less the rail car or warehouse storage quantities.
A small charge of pistol or rifle powder in a case simply cannot support a detonation pressure wave.

If it could, we could not buy it or ship it in 1 pound cans in cases, or 8 pound drums to use for reloading.
It would be an Explosive instead of a Flammable, and the ATF & HLS would have strict oversight on the sale or transportation of it.

If it could, you could stick a blasting cap and a fuse in a can of 700-X, light the fuse, and blow Supermans shorts off.
But you can't, because smokeless powder in small quanities cannot support a detonation pressure wave.

Guns blow up with light charges of fast powder because of double charges, or two bullets in the case, or a bullet stuck in the barrel due to the too small charge.


There is such a thing as SEE, or Secondary Explosion Effect in small-bore magnum rifle calibers using reduced charges of very slow burning magnum rifle powder.

But, IMO, that isn't a detonation either.

It is a bullet stuck in the rifling leade that can't get out of the way fast enough when the reduced load of powder finally lights off completely.

http://www.thehighroad.org/showpost.php?p=5727354&postcount=7

rc

Ex
January 1, 2013, 10:15 PM
Not at all murf! Generated some other good info!

918v
January 1, 2013, 11:51 PM
My 2grs of Bullseye was detonating in my 357. I was there. I saw it. I know I did not double charge it.

rcmodel
January 2, 2013, 12:06 AM
O.K.

But if Bullseye or any other smokeless power could support a detonation wave.

You could make a powerful high-explosive bomb out of a can of it by inserting a blasting cap in the can to initiate a detonation.

But, you can't.

If you could, reloaders, or Achmed The Dead Terrorist couldn't buy it.

But we can.

rc

murf
January 2, 2013, 12:11 AM
rc,

a couple of things:

per the department of transportation, smokeless powder is a class one explosive and must so be marked when transported.

any amount of powder can detonate with enough pressure and temperature.

an s.e.e. is a detonation also, imo. both the s.e.e. and 918v's event both initially have a large enclosed air space to compress. a larger portion of the powder surface area is initially exposed to combustion. lots of heat and lots of pressure.

i think it is possible to have a detonation in both cases.

murf

kingmt
January 2, 2013, 12:20 AM
My guess is what you had was the primer kicking the bullet into the forcing cone & then the pressure building up from the burning powder. Most of which was blowing out your gap. Without the bullet having a good running start you probably did get a pressure spike.

Walkalong
January 2, 2013, 12:33 AM
While Titegroup is advertised as not being position sensitive, in my tests it has proven to be average in that dept. AA #2 and True Blue are some of the least position sensitive powders I have tried as far as position in the case and velocities go. Clays is pretty good as well. Some powders are terrible.

Detonations? Gonna have to prove it to me.

murf
January 2, 2013, 12:39 AM
just pulled up an msds for h4831 (on the hogdon website). it is an explosive.

suggest everyone pull it up and read all the cautions. fwiw

murf

Walkalong
January 2, 2013, 12:42 AM
Smokeless powders are not explosives.

rcmodel
January 2, 2013, 12:56 AM
My guess is what you had was the primer kicking the bullet into the forcing cone & then the pressure building up from the burning powder.+1


Murf:
DOT Division 1.3 Consists of explosives that have a fire hazard and either a minor blast hazard or both, but not a mass explosion hazard. (Examples: Rocket Motors and Smokeless Powder)
(IE: Pressure build-up and intense fire.)

DOT Division 1.1 Consists of explosives that have a mass explosion hazard. A mass explosion is one that affects almost the entire load instantaneously. (Examples: Dynamite, TNT, and Black Powder)
(IE: Detonation.)

rc

918v
January 2, 2013, 02:19 AM
They are not explosives. But Bullseye can detonate when the primer overpowers it. It could be that in a .357 case, 2 grains or less can be detonated with a small pistol primer. A magnum or small rifle primer may detonate a heavier charge weight. A blasting cap could detonate a pound, who knows?

918v
January 2, 2013, 02:23 AM
My guess is what you had was the primer kicking the bullet into the forcing cone & then the pressure building up from the burning powder. Most of which was blowing out your gap. Without the bullet having a good running start you probably did get a pressure spike.


Why did this phenomenon stop completely as soon as I went to 2.2 grains? Normal fouling of the case. Normal muzzle blast. Normal looking primers.

murf
January 2, 2013, 03:10 AM
smokeless powders are explosives. smokeless powders can detonate.

read the msds for any smokeless powder. the powder manufacturer is saying this.

murf

243winxb
January 2, 2013, 09:36 AM
From my link above. The Manufacture of Smokeless Powders and their
Forensic Analysis: The safest and most powerful low-order explosive is smokeless powder. These powders decompose at rates up to 1,000 meters per second and produce a propelling action that makes them suitable for use in ammunition. However, the slower burning rate of smokeless powder should not be underestimated. The explosive power of smokeless powder is extremely dangerous when confined to a small container. In addition, certain smokeless powders with a high-nitroglycerine concentration can be induced to detonate. On the other hand, high-order explosives do not need containment to demonstrate their explosive effects (Saferstein 1998). These materials detonate at rates from 1,000 to 8,500 meters per second, producing a shock wave with an outward rush of gases at supersonic speeds. This effect proves to be more destructive than the fragmented debris.

kingmt
January 2, 2013, 12:30 PM
Smokeless powder won't burn very well without pressure. The more pressure the faster out burns. The faster it burns the more pressure it makes. The primer makes the pressure to start the cycle. Of course you already know the more powder you use will make the pressure rise faster along with a smaller space spotted the build of pressure. The small amount of powder doesn't get started until the bullet gets stuck into the come. it leaking out the gap is why out is so loud.

Seat your bullet a little deeper will make it go away.

murf
January 2, 2013, 01:42 PM
243winxb,

thanks for the info. i guess even scientists can't all agree on how smokeless powder decomposes.

kingmt,

i don't agree with anything you said in post #24.

ex,

can't help you on position sensitivity of powders. never had an event, so far.

murf

kingmt
January 2, 2013, 02:06 PM
Then you don't understand powder.

Walkalong
January 2, 2013, 02:15 PM
Smokeless powder won't burn very well without pressure. The more pressure the faster out burns. The faster it burns the more pressure it makes. This part is definitely true. Powder must have resistance to burn quickly. When totally enclosed it can resemble an explosion. This is also part of the reason a large straight walled case uses very fast rifle powders vs the bottle necked calibers.

Some handgun powders can actually give more velocity when at the front against the bullet, at least in some applications. Two I can remember off the top of my head are Blue Dot & Solo 1250.

The only primer I ever blew severely was with Blue Dot forward against the bullet vs back against the primer. Back against the primer it was fine, but forward it wasn't. Most (Vast majority of those I have tried it with) handgun powders lose velocity if they are forward against the bullet vs back against the primer..

GLOOB
January 2, 2013, 04:52 PM
The small amount of powder doesn't get started until the bullet gets stuck into the come. it leaking out the gap is why out is so loud.
But does this also explain the sticky extraction and the non-sooted cases? By the time the bullet hits the cone, is it still in the case? I think some measuring is in order. This could be the first account of a detonation with pistol powder I've heard that has all the elements and details to confirm the myth.

I'm a little dubious of the simple explanation. I've stuck bullets with much more reasonable charges. If the bullet were sticking in the cone on such a small charge, I wonder that it would make it out the barrel.

kingmt
January 2, 2013, 06:12 PM
That part of it is a guess. I'd say it is a the primer sticking it in the cone. Then the powder lites.

rcmodel
January 2, 2013, 08:52 PM
I have to agree.

I can think of no other logical explanation why 2.0 Bulleye + a 148 wadcutter in a .357 case can "detonate".

But 2.7, or 3.0 grains, which have been standard target & plinking loads for many decades, cannot.

It has to have something to do with the bullet starting by the primer, then stopping in the forcing cone sealing the B/C gap.

Then it can't get out of it's own way fast enough before the tiny charge lights, and pressure builds in the case enough to blow the primer.

A true Detonation would shatter the cylinder of even the strongest revolver.

rc

holdencm9
January 2, 2013, 11:00 PM
I am no expert, but if pressure builds up in a container, and then the container blows, that is not technically a "detonation" is it? More likely it is deflagration and a bursting at the seams.

"When a low-speed deflagration occurs within a closed vessel or structure, pressure effects can produce damage due to expansion of gases as a secondary effect. The heat released by the deflagration causes the combustion gases and excess air to expand thermally. The net result is that the volume of the vessel or structure must expand to accommodate the hot combustion gases, or the vessel must be strong enough to withstand the additional internal pressure, or it fails, allowing the gases to escape. The risks of deflagration inside waste storage drums is a growing concern in storage facilities."

http://en.wikipedia.org/wiki/Deflagration

rcmodel
January 2, 2013, 11:44 PM
that is not technically a "detonation" is it?You are doing better then some of us here.
And you are entirely correct.

A detonation:
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it.

The shock wave from a true detonation shatters steel instead of expanding and tearing it due to exceeding of the elastic limit of the steel.


That is why I keep arguing that smokeless powder cannot Detonate.

If it could, your local reloading supply place would be the store of choice for every mad bomber in the world.

Instead, they go to Semtex-R-Us to get their reloading supplies.

Smokeless powder cannot support a supersonic shock wave in less then rail-car or warehouse quantities.

The difference is, smokeless powder deflagrates, or burns very rapidly.
There is no, and can be no supersonic shock wave accelerating through the medium, when the medium is 2.0 grains of pistol powder!

rc

GLOOB
January 3, 2013, 12:14 AM
The shock wave from a true detonation shatters steel instead of expanding and tearing it due to exceeding of the elastic limit of the steel.

A detonation does not necessarily shatter steel no matter what. If the steel is thick/tough enough, you need to use x sticks of dynamite instead of one. And certainly a blasting cap, alone, produces a detonation, but I don't see a blasting cap shattering an I-beam. So, realistically, a detonation could occur in a gun without blowing it up. Pressure waves have both a propagation speed and an amplitude. If you meet the minimum speed of 8000m/s or w/e it is, you have a high explosive detonation. The amplitude can still be so small it doesn't shatter a gun.

If it could, your local reloading supply place would be the store of choice for every mad bomber in the world.

Instead, they go to Semtex-R-Us to get their reloading supplies.
Perhaps it's because it's difficult and unpredictable to produce a detonation this way, and it would require a very high pressure vessel to duplicate. If the container has to be that strong, it might weigh more than what you're trying to blow up. Just because it could doesn't make it practical.

rcmodel
January 3, 2013, 01:20 AM
Perhaps it's because it's difficult and unpredictable to produce a detonation this way,It still would not produce a detonation.

It would produce an explosion caused by the deflagrateion of the smokeless powder rupturing the pressure vessel.

But it would not produce a detonation, because it can't.
The energy of the smokeless power "fuel", and high-speed shock wave propagation through the smokeless powder "medium" just isn't there, or even possible in small quantities.


Again, if it were any way possible to produce a detonation with the smokeless powder used in reloading?
We couldn't buy it over the counter.

Because the government would classify it with all the other high-explosives that can produce a detonation such as dynamite, nitroglycerin, TNT, C4, blasting grade ammonium nitrate, Semtex, etc.

rc

918v
January 3, 2013, 01:58 AM
That is why I keep arguing that smokeless powder cannot Detonate.

That is an inaccurate blanket statement. Some smokeless powder can detonate under some circumstances.

GLOOB
January 3, 2013, 02:37 AM
Again, if it were any way possible to produce a detonation with the smokeless powder used in reloading?
We couldn't buy it over the counter.

Almost any flammable vapor or fine powder can detonate in large quantities in open air. The large quantities are needed for the deflagration/flame front to build the required pressure and temperature to detonate.

Almost any flammable vapor or fine powder can detonate in small quantities in an enclosed space. The pressure and temperature are achieved because of the confinement.

Gasoline vapors can detonate in a combustion engine in very, very small quantities in the very small cylinder of an engine. Gasoline is legal to purchase, despite this. Engines don't automatically blow up, despite this.

Yes, I understand the average pipe bomb blows up due to pressure exceeding the container's limits. But under the right conditions detonation can occur.

7075-T7
January 3, 2013, 10:58 AM
Gasoline does not detonate in engine cylinders. The flame front speed is less than supersonic.

243winxb
January 3, 2013, 11:08 AM
http://firearmsid.com/Feature%20Articles/McCord_gunpowder/index.htm :banghead:

918v
January 3, 2013, 11:57 AM
From the above link:


The safest and most powerful low-order explosive is smokeless powder. These powders decompose at rates up to 1,000 meters per second and produce a propelling action that makes them suitable for use in ammunition. However, the slower burning rate of smokeless powder should not be underestimated. The explosive power of smokeless powder is extremely dangerous when confined to a small container. In addition, certain smokeless powders with a high-nitroglycerine concentration can be induced to detonate. On the other hand, high-order explosives do not need containment to demonstrate their explosive effects (Saferstein 1998). These materials detonate at rates from 1,000 to 8,500 meters per second, producing a shock wave with an outward rush of gases at supersonic speeds. This effect proves to be more destructive than the fragmented debris.

243winxb
January 3, 2013, 12:12 PM
induced to detonate. Yes, in a pipe bomb.:evil:

murf
January 3, 2013, 03:50 PM
918v,

what primer were you using with that 2 grain load?

243winxb,

half a pound of powder in a pipe bomb sounds like a double or triple charge of bullseye in a 38 special round. don't need detonation for that guns cylinder to let go, or that pipe to turn into shrapnel.

7075-t7,

gasoline detonates inside an engine, called engine knock, when combustion chamber temps rise, air/fuel mixture gets lean and ignition timing advances. happens a lot during the arizona summer. left to its own devices, engine knock will punch a hole in the top of the piston.

sounds like the rate of decomposition for smokeless powder can vary greatly depending upon circumstances and surroundings. i learn something new every day. also, i understand that mother nature does not live by our rules, we live by hers.

murf

918v
January 4, 2013, 01:04 PM
918v,

what primer were you using with that 2 grain load?



I was using WSP, FC-100 and CCI-500. It pierced some of them too.

kingmt
January 4, 2013, 10:35 PM
Again just my logic on it but if the powder lite off after the bullet left the case tyre weakest side would no longer be the bullet leaving the case it would be the case slamming back.

Big JJ
January 4, 2013, 11:04 PM
Team
Maybe your right or maybe your wrong I don't know although I do enjoy reading all of the opionions and facts.
But my question is should we be broadcasting this news to the world?
Referancing RC's quote below:
(Because the government would classify it with all the other high-explosives that can produce a detonation such as dynamite, nitroglycerin, TNT, C4, blasting grade ammonium nitrate, Semtex, etc.)
A reclassifaction of smokeless powder by the Fed.could be a form of gun control that they do not need to vote on.
Not somthing I want.
Just my 2 cents.

Walkalong
January 5, 2013, 03:00 PM
If they try to reclassify it, it won't be because it is dangerous like real explosives, it will just be a way to harass gun owners, but, there are many more real and pressing issues to get involved in right now.

Call, write, donate,........ :)

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