Let's Blow Up Some Rifles, Boys...

[Guy La Pourqe]

I love having Saturday coffee with King Peter. We always find something to fight about and this time it was all about gun powder burn rates, pressure spikes and theory - and I think I got spanked. (Not that Pete would ever admit that he's wrong, may God rot his balls!:dung_hits_fan:)

Agree or disagree with the following statements:

A. You can never blow up a gun with an overly slow burning powder because any unburned powder will be pushed out the barrel and burn out there - and that would dispense with excess powder). For the record I am not sure I agree with that.

B. Take two cartridges with roughly the same dimensions but different bores (eg. 243 vs 308): You will need a faster burning powder for the 308 than for the 243 because as the 308 travels down the bore, the volume increases and you need a faster burning powder to fill that volume. For the record, I disagree with that. I would think you need a faster burning powder in the smaller bore rifle because you want the combustion cycle to end just as the bullet leaves the barrel - and the smaller volume of the smaller bore would call for a faster burn rate. Of course when we brought up the powder burn rate chart on the cell, the 243 does seem to favour slower powders. That sticks in my craw because typically - don't the big boomer magnums burn smaller powder?

I think Pete may be right but for the wrong reasons. He finished up his flubdubbery with the statement that optimal powder burn rate is a function of bore diameter. Are any of you boys up to speed on the physics of pressures vs. cartridge vs. powder selection?

[gnostic]

Normally, you can't get enough slow burning powder in the case, to blow up the gun.

[Mica_Hiebert]

A: is assanine and your friend is welcome to earn his Darwin award if he puts this to practice.

B: well I'm still concerned about A:

[Mica_Hiebert]

Normally, you can't get enough slow burning powder in the case, to blow up the gun.

Load up a rifle case with pistol h110 powder, I'll hold your beer and watch.

[Hick]

What you do is take a relatively large case-- like 30-06. Fill it about 50% with a slow burning powder, then seat the heaviest bullet you have. Then, put it in your rifle horizontally-- so that the powder lies flat all along the length. In this position, the primer fire can reach almost all the powder at the same instant. So-- instead of burning from the primer toward the bullet, it all lights up at the same time. That can blow up your rifle. I can't guarantee it will wreck your rifle, but I wouldn't try it in mine.

[Jedman]

Kinda hard to give you a clear answer on either.
For A - To many variables to say never, but in general what gnostic said is true.

For B - Again really you have to be comparing apples to apples, If you compare a 243 Win to a 358 Win both the same basic case but you could be shooting a lightweight bullet in the 243 ( 58 gr. ) and a heavyweight bullet in the 358 (250 gr. ) and use the same powder for both and get near the highest velocity at a safe pressure in both. But if your talking 100 gr. bullet in the 243 you will need a slower burn rate powder than the 358 to get maximum velocity at a safe pressure.
About as clear as mud.

Jedman

[HangFireW8]

On B, efficiency is NOT performance. Drag racers will gladly burn twice the fuel for another 0.1 second off their quarter mile. And powder blown out of the barrel may be inefficient, but it may also be the load that produces the best performance within safe pressure limits.

[uscra112]

The ballistic engineering explanation of the S.E.E. phenomenon is this: Load a slow burning, hard-to-light powder into a large case, behind a strongly constructed jacketed or solid bullet. The primer fires, and drives the bullet into the throat, where it stops. It is now a bore obstruction. Millisecond or two later that slow powder finally lights, the bullet doesn't move, and pressure goes thru the roof. BOOM! This was actually observed with an instrumented gun by a lab in Europe while working up a load for a large case 6.5 mm cartridge with a long "cruise missile" style bullet. Put to rest all the old wive's tales about powders detonating and such.

So yes, it's possible. Not with cast lead, however.

[GhostHawk]

As far as I know A is only true for black powder. I would not try it with smokeless.

[Huvius]

Don't know about A but in a straight walled case I could see that being so.

As for B, "overbore" cartridges, meaning large case body to bullet diameter ratio, are more efficient with a slower powder.
The 243 fits into this category and the ballistics of the cartridge bear this out.
This is generally true with standard cartridges when using heavy for caliber bullets as well.

The theory is that the pressure curve is more gradual with a slow powder so the energy expended on the bullet's acceleration happens throughout the travel down the bore.
This is why pistols use smaller charges of faster powders as the opportunity for acceleration is hampered by the barrel's short length.

[Skipper]

I would think you need a faster burning powder in the smaller bore rifle because you want the combustion cycle to end just as the bullet leaves the barrel

Just for info, the powder is consumed in about 3.5-4" of the barrel. It's all gas expansion after that.

[country gent]

Try the slow powders in some semi auto and see what happens, To slow a powder in the garand will bend the op rod as it changes the port pressures. Even the AR15 starts doing strange things with slow powders. While they may not "blow up" the gun, damage is damage

[HangFireW8]

The ballistic engineering explanation of the S.E.E. phenomenon is this: Load a slow burning, hard-to-light powder into a large case, behind a strongly constructed jacketed or solid bullet. The primer fires, and drives the bullet into the throat, where it stops. It is now a bore obstruction. Millisecond or two later that slow powder finally lights, the bullet doesn't move, and pressure goes thru the roof. BOOM! This was actually observed with an instrumented gun by a lab in Europe while working up a load for a large case 6.5 mm cartridge with a long "cruise missile" style bullet. Put to rest all the old wive's tales about powders detonating and such.

So yes, it's possible. Not with cast lead, however.

This is not the definition of SEE, nor is it just possible "Not with cast lead".

SEE is the transition of burn rate from deflagration to detonation. While it may coincide with the description above, it doesn't have to, it is a chemical property of the energetic material (propellant), usually involving double base propellants containing 1,2,3-trinitroxypropane.

Think of it this way. Throw genuine dynamite (diatomaceous earth + nitrogyclerine) in a fire, it burns real good. Hit it with a blasting cap, it explodes. That is the difference between deflagration and detonation, and the difference between a good powder burn and SEE. Many think of smokeless powder as exploding because its burn rate seems fast to us humans, but it is an order of magnitude slower propagation rate than detonation. In a gun chamber smokeless powder burns faster than in open air due to higher pressure, but still not fast enough to call it detonation (unless SEE occurs).

[uscra112]

This is not the definition of SEE, nor is it just possible "Not with cast lead".

SEE is the transition of burn rate from deflagration to detonation. While it may coincide with the description above, it doesn't have to, it is a chemical property of the energetic material (propellant), usually involving double base propellants containing 1,2,3-trinitroxypropane.

Think of it this way. Throw genuine dynamite (diatomaceous earth + nitrogyclerine) in a fire, it burns real good. Hit it with a blasting cap, it explodes. That is the difference between deflagration and detonation, and the difference between a good powder burn and SEE. Many think of smokeless powder as exploding because its burn rate seems fast to us humans, but it is an order of magnitude slower propagation rate than detonation. In a gun chamber smokeless powder burns faster than in open air due to higher pressure, but still not fast enough to call it detonation (unless SEE occurs).


I "SEE" that science and engineering proofs still haven't penetrated the whole population. Do you also believe in AGW?

[500Linebaughbuck]

Load up a rifle case with pistol h110 powder, I'll hold your beer and watch.

can i watch too? like 100 or so yards away.....

[gnostic]

Load up a rifle case with pistol h110 powder, I'll hold your beer and watch.

H110 isn't a slow burning powder for a rifle....

[rking22]

A,, never said never! "In general "kind of rules can lead to BAD things . Documented handguns blown up with reduced loads of 296/h110. If he's talking 4064 In a 375 winchester then I can go along. Never said never, and ect

B , he's right for the wrong reasons. A larger bore cartridge with the same ish powder capacity will generally, with similar bullet type and sectional density, generate lower peek pressures with the same powder. Again see my thoughts on "A",
There exist test equipment and pressure tested results too keep the excitement level down.
True that the larger bore gives a quicker increase in combustion area, and as long as it's a fun conversation over a beer, interesting. Not a good idea to use generalizations to select powders, some powders do NOT follow the rules. H110 being one of those, and NOT a slow rifle powder.

[Walter Laich]

help: AGW???

[Larry Gibson]

The ballistic engineering explanation of the S.E.E. phenomenon is this: Load a slow burning, hard-to-light powder into a large case, behind a strongly constructed jacketed or solid bullet. The primer fires, and drives the bullet into the throat, where it stops. It is now a bore obstruction. Millisecond or two later that slow powder finally lights, the bullet doesn't move, and pressure goes thru the roof. BOOM! This was actually observed with an instrumented gun by a lab in Europe while working up a load for a large case 6.5 mm cartridge with a long "cruise missile" style bullet. Put to rest all the old wive's tales about powders detonating and such.

So yes, it's possible. Not with cast lead, however.

This is the correct definition of S.E.E. There is not "detonation" of the powder. The powder burns faster than the bullet can get moving again with the pressure rising to catastrophic levels. The brass case, the barrel and or the action can no longer retain the pressure and it lets go.

[HangFireW8]

This is the correct definition of S.E.E. There is not "detonation" of the powder. The powder burns faster than the bullet can get moving again with the pressure rising to catastrophic levels. The brass case, the barrel and or the action can no longer retain the pressure and it lets go.

The ballisticians I worked with at Ballistics Research Lab, APG disagree with you.

So does the data I reduced for them.

[Texas by God]

Optimal powder burn rate is determined by bullet diameter/weight AND case capacity. Quit having coffee with that guy

Sent from my SAMSUNG-SM-G930A using Tapatalk

[John Taylor]

I have a 45-70 trapdoor that blew up from not having enough powder. Cartridge was loaded with a 240 grain bullet and 40 grains of RX7. Lots of air space, gun was pointed down to load and then raised up to level. Breach block staid in action but top of action was gone and the barrel was pealed back like a banana. About 4" of the stock was gone. Luckily no one was hurt.

[Larry Gibson]

John

That is the 3rd case of S.E.E. in a 45-70 that I am aware of. The other 2 were both Contenders using 2400 powder and 300 gr bullets. Same scenario; light bullet, lots of air space, muzzle raised to fire leaving air space to rear and powder forward in the case. Primer drove bullet into throat, bullet stuck then powder started burning.

Was the S.E.E on the 1st round or was the barrel fouled from previous shots?

[Larry Gibson]

The ballisticians I worked with at Ballistics Research Lab, APG disagree with you.

So does the data I reduced for them.

A lot of ballisticians believed that until S.E.E. was replicated in a lab with equipment that actually measured what was happening. I believed it as did most all the gun writers and sages not to many years distant. Some still believe the "wave" and "detonation" theories........but then some still believe the world is flat.

Point is S.E.E has been and can readily be produced now that we understand what causes it. It was the advent of peizo-transducer measurement of the pressure curve (trace) that gave us the answer.

[jonp]

Load up a rifle case with pistol h110 powder, I'll hold your beer and watch.
I dont think that is a valid point of view. H110 may be a slow pistol powder but is a fast rifle powder.
More accurate would be slow pistol powders in pistols and slow rifle powders in rifles.

If you can blow a 25acp up using H110 or a 223 using H870 id like to see it

[Chev. William]

I dont think that is a valid point of view. H110 may be a slow pistol powder but is a fast rifle powder.
More accurate would be slow pistol powders in pistols and slow rifle powders in rifles.

If you can blow a 25acp up using H110 or a 223 using H870 id like to see it

Yet H110/W296 is used in .30 Carbine Cartridge.

Chev. William

[jonp]

Yet H110/W296 is used in .30 Carbine Cartridge.

Chev. William

Ok, Chev.?

[HangFireW8]

A lot of ballisticians believed that until S.E.E. was replicated in a lab with equipment that actually measured what was happening. I believed it as did most all the gun writers and sages not to many years distant.

Larry, I got zero of my information from gun writers or secondary sources.

Some still believe the "wave" and "detonation" theories........
There are theories. And then there is a very expensive Rheinmetall test barrel we were forced to retire after a pressure excursion. And then there is all those lovely sine waves rolling through the 8 Kistlers in the chamber, back and forth, back and forth... hard to not believe in the data, especially where the peaks coincided. And then what happened after the peaks coincided.

It was cheap to let the new guy burn time graphing data in the hopes of saving the barrel... but not all things work out the way we plan. You see, the data just doesn't lie.


but then some still believe the world is flat.
Well now, isn't that the Larry we all know and love? How 'bout we stick to the discussion?

Isn't is possible... that there is more than just one mechanism involved here? Perhaps I missed the narrowing of the definition of SEE and maybe, just maybe, I've gone beyond that level of discussion. Maybe we can be more than journalists, who find a source or two to quote and then stand that one point up against all other knowledge, even where such knowledge can co-exist.


Point is S.E.E has been and can readily be produced now that we understand what causes it. It was the advent of peizo-transducer measurement of the pressure curve (trace) that gave us the answer.
And my job was to calibrate, install and remove those Kistler gauges. Every P.I. had their own sets and it was my job to calibrate, track them, install them, etc.

I noticed you completely fail to address energetic materials transcending one rate to another. But I'm no longer asking you to.

You see, I'm done discussing SEE on this board. I no longer have access to the library at APG, and even if I did, the work we did is not publicly available to cite & be verified. And I may be done with this board. We'll have to see. I greatly dislike the quick transition to ad hominem so common in your discussions.

[Texas by God]

A gun can be blown up by using too much fast burning powder or by using too little slow burning powder. Half a case full of Bullseye will kaboom your 7 mag; so will half a case full of IMR 7828.
Let's just use those loading manuals with their tested data.

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[John Taylor]

John

That is the 3rd case of S.E.E. in a 45-70 that I am aware of. The other 2 were both Contenders using 2400 powder and 300 gr bullets. Same scenario; light bullet, lots of air space, muzzle raised to fire leaving air space to rear and powder forward in the case. Primer drove bullet into throat, bullet stuck then powder started burning.

Was the S.E.E on the 1st round or was the barrel fouled from previous shots?

The new barrel had been test fired with factory ammo before I sent it out. The first shot with the light load and it went boom. The same load in a Martini shot OK but then the gun was not pointed down to load. I had heard of detonation before but this is the first and only experience with it. I read someplace that in test they got 130,000 psi, that's a little to much for a trapdoor.

[John Taylor]

Maybe this will help http://guns.connect.fi/gow/nitro.html

[GARD72977]

This is the most useless thread on castboolits!!!!!!

[Larry Gibson]

HangFireW8

You are correct, there are more "mechanisms" at play here. However, none of them demonstrate smokeless powders "detonate" when loaded in cartridges. Yes, they (the really fast burning powders) can be made to detonate with the use of multiple blasting caps as explained in the treatise John Taylor gave in post #31. However, we are not using blasting caps to detonate the powder. We are using primers which ignite the powder to cause it to burn. The "waves" as measured by Kistler gauges do not have the velocity of the shock waves created by blasting caps.

"Pressure excursions are easy to replicate with any "overload". True S.E.E events are difficult to replicate because certain elements or a combination of those elements must occur. S.E.E events can be easily created if we set up those elements to occur. Even then, with the elements in palce the powder does not "detonate" but burns creating a "pressure excursion" of catastrophic proportions because the bullet is not moving fast enough.

As an example let's take a 30-06 with a max load of 3031 under a 150 gr jacketed bullet. All is fine and we can shoot that load without having any "pressure excursions". However, if we simply replace the 150 gr bullet with a 220 gr jacketed bullet under that same max load what happens? A major "pressure excursion" will happen. Does the 3031 detonate? No, it does not. Why? Simply because the heavier bullet could not move fast enough down the barrel to alleviate the pressure before the pressure reached catastrophic levels.....the "pressure excursion". The high pressure event is still caused from the 3031 powder burning, not detonating.

I never said there weren't the "waves" measured by the Kistler gauges. I said/implied there wasn't any documented and laboratory reproducible evidence that those "waves" caused the powder to detonate. The measurement of a "pressure excursion" is a measurement of high pressure above an established norm (in this case not exceeding the structural limits of the test firearms, fixtures or barrels). That your test barrel was swollen and damaged does not demonstrate the powder detonated. The damage only demonstrates there was excessive pressure.

I measure pressures of numerous cartridges in numerous test firearms/barrels. I have had an S.E.E. and have come close to several others. We can see the onset of an S.E.E. by the pressure traces and actual pressure reading (peak and rise of the pressure). I also have pressure traces demonstrating the "waves" as also measured by the Kistler gauges. Thus I have replicated the lab results posted in the article I quote from. I am not a "journalist". I report facts based on actual test results.

It is unfortunate you no longer have access to the APG data. It would be interesting to see it.

[HangFireW8]

For any SEE-type event, calculate the temperature it takes to get the volume of powder-gas up to the pressure required for the failure. If you surpass the surface of the Sun, then you have to look for other explanations.

That's a good article. I was aware of it a few years back, but it taught me nothing new. Glancing over it I find nothing to disagree with.

OK I'm really done.

[Larry Gibson]

This is the most useless thread on castboolits!!!!!!

Since when was usefulness a criteria?

[uscra112]

How can smokeless powder detonate? The molecules aren't unstable enough to be broken down by a shock wave, which is how high explosives work.

Just as a historical datum: American WW2 hand grenades were filled with blank-fire powder, not a high explosive. They exploded just fine, but they did not detonate.

[Good Cheer]

On B, efficiency is NOT performance. Drag racers will gladly burn twice the fuel for another 0.1 second off their quarter mile. And powder blown out of the barrel may be inefficient, but it may also be the load that produces the best performance within safe pressure limits.

In the 1980's I tried my hand at designing a cast boolit cartridge for deer hunting to work on that concept.
Wanted the right case volume for the bore and boolit weight, an elongated pressure curve to avoid destructive plastic deformation.
Load testing with progressively faster powders reduced the vertical stringing until plastic deformation produced lateral increases in group size. That's how I verified the powder burn rate suited to the case, the boolit and the rifle. It ended up being in the IMR4320 to 760 neighborhood with magnum rifle powders. Then the serious development began.

That's not gonna work for people who are not working with the equipment I was working with but thought I'd throw the saga out there by the campfire just the same.

[Good Cheer]

Hmm, maybe I could finagle adapting that technique to working up loads for 9.3x74R.

[Chev. William]

Ok, Chev.?
I have read of H110 Loads for the .30 carbine cartridge, using RN 110Grain FMJ bullets (similar to Military Ball ammo) that list charges from 80% fill to 97% fill yet The 'Warning on H110 say keep within 3% of Max Charge when using H110/W296 Propellant.

This seems to be a Contradiction.

Chev. William

[EDG]

I don't think the original poster knows enough to have a reasonable conversation on the subject.

Some of his question can be answered by studying powder volumes powder specific gravities and powder burn rates.

He should study loading data until he is sure that he knows the right answer.

[Larry Gibson]

I have read of H110 Loads for the .30 carbine cartridge, using RN 110Grain FMJ bullets (similar to Military Ball ammo) that list charges from 80% fill to 97% fill yet The 'Warning on H110 say keep within 3% of Max Charge when using H110/W296 Propellant.

This seems to be a Contradiction.

Chev. William

I believe the original intent of that warning was with handgun loads intended for use in revolvers with barrel/cylinder gaps.

[John Boy]

Load up a rifle case with pistol h110 powder, I'll hold your beer and watch. Load up a case with Alliant 300-MP, slow burning pistol powder with a couple of notches slower than H110 and watch from ... a long distance away!