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First off this is not mine.

A buddy emailed this to me.

Enjoy and be happy it was not you!

Terry
 

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Hmmm, maybe a caseload of Bullseye wasn't such a good idea.

Don
 

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I am guessing S&W won't "repair or replace"? :shock:

Seriously, this is why it is so important to pay attention to the loading books and components at hand. Yikes!!
 

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I had a 29 do that on WWB ammo. When I calmmed down I looked at the cylinder walls of the undamaged walls and noticed defects where each of cuts were for the lock up. Under closer examination all three showed cracks starting. I FIRMLY do not believe it was the WWB ammo as that was "gentle" as far as most factory ammo was concerned.
 

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It has always been normal to blame the location of the stop notches and when S&W did the re-work of the M29 back in the 90s those were changed. If they were a significant weakness I'd think we would see lots of failures such as these pictures show, but absent overloaded ammo how can that explain why the charge holes on both sides go too?

I've only seen a few, but the metalurgical reports on this type of catastrophic failure always include "high pressure" as a cause.
 

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This showed up on the S&W forum awhile back and the consensus was a large overcharge of very fast powder. Takes a high-order of detonation to remove the topstrap, let alone, remove the adjacent chambers.
 

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[quoteTakes a high-order of detonation to remove the topstrap, let alone, remove the adjacent chambers.
][/quote]

Not so. 75- 80,000 psi will do it.

While it is a handy excuse to say "detonation" nobody has ever been able to produce it in a laboratory.

This is something I have really studied but the best documentation was provided by the NRA and H.P. White that was published in the December, 1978 American Rifleman. At that time people were claiming that a charge of 2.7 gr. Bullseye in a .38 Special "detonated" and produced exactly the destruction shown.

They used pressure test equipment and even went so far as to replace the primer with PETN (balasting cap stuff) and could not get anywhere. They finally were able to blow guns up at will, but only with a double charge (5.4 gr.) AND seating the wadcutter bullet below the case mouth by 3/16". That gave a pressure of 76,100 psi and a catastrophic failure. A simple double charge only gave 32,300 psi.
 

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Back in the early 1990s, there was a fellow who shot IPSC with us using one of the Springfield Factory Comp P9 in .40 S&W. At indoor matches, we marveled at how his comp always blew the insulation off of the ceiling baffles. It looked like a snow storm, and his head and shoulders would be coated with it by the end of the stage. Later when the state match rolled around, we found out the reason why. He was running a power factor in the 210+ range! When asked what his load was, he explained that he just took the primed case, and scooped it into the powder to fill it. :shocked:
 

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Decades ago, I was in a now-defunct gun store in Pittsburgh and observed a gun enter the store cursing at high volume and proceed to the counter with a box in hand. Briefly he was complaining about a "defective gun" he wanted replaced.

Opening the box displayed a Colt Diamondback with the tops of 3 chambers gone, the topstrap bowed and the barrel pointing downward at an intersting angle.

A little quiet discussion revealed he was using Bullseye powder since he was loading target loads and was filling the case. Don't recall what HP White got when they tested some of his remaining roman candles, but it was noteworthy.
 

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Okay Charlie, maybe detonation was the wrong term to use. It seemed alot easier to say than 'Rapid over-expansion of the chamber due to an inordinately-large powder-charge thereby deposing the topstrap and adjacent chambers from the immediate area of operations.'

Can I be a gun-writer now??? LOL!! Just kidding around Charlie.

:lol: :lol: :lol: :lol:
 

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Charlie Petty said:
[quoteTakes a high-order of detonation to remove the topstrap, let alone, remove the adjacent chambers.]

Not so. 75- 80,000 psi will do it.

While it is a handy excuse to say "detonation" nobody has ever been able to produce it in a laboratory.

This is something I have really studied but the best documentation was provided by the NRA and H.P. White that was published in the December, 1978 American Rifleman. At that time people were claiming that a charge of 2.7 gr. Bullseye in a .38 Special "detonated" and produced exactly the destruction shown.

They used pressure test equipment and even went so far as to replace the primer with PETN (balasting cap stuff) and could not get anywhere. They finally were able to blow guns up at will, but only with a double charge (5.4 gr.) AND seating the wadcutter bullet below the case mouth by 3/16". That gave a pressure of 76,100 psi and a catastrophic failure. A simple double charge only gave 32,300 psi.
Yes, I remember the pre-Internet rumor of the cause of the "Bullseye Surprise" being rather soundly debunked.

So much of the body of knowledge seems to be getting buried these days.

On the other hand, the "Secondary Explosion Effect" (mis-named!!! It's just a severe pressure excursion or "spike") does appear to have some basis in a credible theory, complete with the unpredictability of barrel friction interrupting the normally-continuous increase in burning chamber volume. But that is the opposite situation, slow-burning powders, heavy bullets, and rifle calibers with rifle powders.
 

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I was able to do some work looking into the so called SEE and it was possible to produce a situation where the bullet left the case and went a few inches down the barrel and stopped. Mr. Newton was right and once it stops it takes a lot to get it moving again but the powder was continuing to burn behind it and in a worst case stuff came unglued.

This was documented with pressure measuring equipment. I did this a long time ago and do not recall the precise numbers but they were >100,000 psi.

The industry term is "bullet in bore" which is accurate but does not really describe the effect. It is emphatically NOT an explosion. In the early stages there was not enough gas produced to keep the bullet moving and it became a body at rest.

Slow burning powders were a key element but some other conditions had to be met too. A rough bore, excessive freebore or eroded throat were contributing factors because the primer impulse alone might be enough to push the bullet out of the case (the engineers called it "de-bulleting") but the powder couldn't keep it going.

On a time/ pressure graph there would be an initial spike that fell off quickly to zero- or at least below the sensitivity of the gauge- when the bullet stopped and then an almost striaight up line to a pressure far above the strength of brass or gun.
 

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Yup. A simplistic language dictionary definition would call an SEE event an "explosion" based on the release of high-pressure gas, but I believe the scientific/engineering meaning of "detonate" fits something called "adiabatic shock".

Explosives have wavefront propagation speeds along the order of 10,000 fps or more, IIRC.

Ah, the memories:
It may have been leaking natural gas combined with free O2 from the ammonium perchlorate which ultimately led to what I *believe* was the adiabatic shock that lit off maybe 100 or more pallets of ammonium perchlorate and/or other chlorate oxidizers all at once in my hometown one fine May day in 1988.

I was trying to figure a way to take a hot local brunette to tour the neighboring marshmallow factory the next week or two, but removal of most of its roof in the "incident" took that off the options list.

Most of the workers at the place, and another nearby one which also made AP and other oxidizers, needed some education about the extreme conditions wherein a mere oxidizer could explode without a fuel being added to the mix.

Yeah, propellants *don't* behave like explosives. That's why terrorists DON'T use Bullseye or any other nitrocellulose product to try to blow up planes.
 
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