Many thanks to all those involved, and especially the gun owner, with whom I have spoken and who graciously agrees to ship the barrels to me for an evaluation

The gun is a 1908 Reg. frame 16g No. 0 L.C. Smith with fluid steel barrels.
The shells were Cheddite for Herters "Select Field Dove and Quail" 1 oz. at 1165 fps, or the old 2 1/2 Dr. Eq. I have no pressure data for that load, but similar loads run about 9,000 psi.

The gun has been used regularly since purchased 2 years ago. The chambers have been measured at 2 3/4"; suggesting the chambers have been lengthened unless the barrels are so marked.

The blow-up occurred on the Sporting Clays course. The shooter did not perceive anything out-of-the-ordinary before or with the blow-up; other than the load report in his ear. No increased recoil. A piece/pieces of barrel struck the tree to the right but was not recovered. I failed to ask him if there was any chance that a 28g shell could have been in his vest, but will do so.

Images courtesy of Dr. Jim, which I believe show a ring bulge at the forcing cone suggesting an obstruction





The shell used at the blow-up. Clearly the Cheddite hulls have a separate plastic base wad



Fortunately, the shooter has the 6 hulls used immediately before the blow-up, and believes the base wad is present and intact in each.

He will send me the barrels, the 6 shells used before the blow-up, the blow-up hull, the remainder of the unfired shells, and the shell box.

Almost never do we have an opportunity to analyze an event like this, and can always learn something when we are able to do so. Stay tuned!

Can’t tell from a photo, but that chamber sure looks thin.

Thin, and rough.

Best,
Ted

I agree- looks like tool marks in the chamber area- were there other 16 gauge shell lengths in 1905 when this Field Grade Smith was mfg'd.?? I thought back then 2&9/16" for 16 gauge, 2 & 3/4" for 12 gauge in the L.C. Smith standards--

Two things, however- (1) neither the shooter or any by-standers were hurt (although I suspect it will take a lot of Pine-Sol to get the brown greasy stains off the gent's shoes- and (2) It was a Field grade, not a A-3-- RWTF

Best I can do with the image. Lots more to follow.

Good close detail- now I am wondering about the possible tool marks- as you would think they would follow the 360 degree I.D. of the barrel chamber- the grooved mark I can see looks to be maybe a fraction of a full 360 degree arc--

what is the barrel wall thickness in front of the chambers of both barrels?

The tool marks seem to suggest that the chambers were lengthened with a common hand drill with dull bits.

That let go at the breech.
Look at the shell.
Look how thin the chamber wall is at the rib.....one of the most important places we cannot measure wall thickness.
Look how compromised the chamber to rib solder is.....it is black and crumbly, looking just like the little chunk missing about half way down the chamber I bet that was there a while...little chunk or pit let go, eat solder from inside out and after some time.....boom.

I see no ring bulge, I see the back of the chamber letting go and peeling the barrel forward.....not saying for sure it was not obstructed but that was going to go....sooner not later.

Hunter Arms used a brazed hook and rib extension



and the wall adjacent to the (sorta) triangular hook piece and top rib extension piece was flat

The whole chamber is one giant ring bulge.

This looks for all the world like a 28/16 accident.

Drew, thanks once again for your time and effort on accidents like these. It's something all of us who shoot old shotguns need to think about.

I have a number of once fired Herter's 16ga hulls on hand. Like virtually all 2 3/4" shells, they're a little short of that mark--but not much. I get them at about 1/32" short of 2 3/4". So definitely longer than what was probably an original 2 9/16" chamber (possibly lengthened).

I'm with you. I instantly focused in on the back of the chamber by the rib. Very thin and part of that fracture looks old and well fouled, as if it had been broken for a while before the coup de grâce.

I don't think a 28 gauge skell will lodge in a 16 gauge gun. As far as I know, that will only occur with a 12/20 combination

Scary how thin the chamber has been filed on the inside near the rib! Gives me chills just to see it! And yet, I have a number of guns joined the same way. Makes one appreciate one piece monoblocked barrels or The Sauer shoe lumps.

It is not as well known as it is a less common occurrence since the 16ga is not normally shot in any of the regular Clays games, but Yes a 28 ga shell will lodge in the forcing cone of a 16 gauge gun, same as will a 20 in a 12.

From the appearance of the chamber, I would guess it has been lengthened & not an expert job by any means. I seriously doubt though that was the cause of the burst. Wile the 2 9/16" was standard for the 16 in that era American Guns were not universally marked for chamber length & were available "On Order" in several different lengths. As I recall in 16 they could be ordered in 2 9/16",
2 3/4", 2 7/8", 3" as well as 3¼". In many cases, A "Long cone" generally means at least the cone has been lengthened & often the chamber as well. it truly is anyone's guess as to what the original chamber length was. Many chambers, however, were lengthened with reamers having standard cones prior to the long cone becoming popular.

Very lucky no one was hurt. Gives me even more reason to never alter a forcing cone or chamber. Wish I had wised up years ago. That chamber does look thin and the black area worries me a bit. A split with let go?

I imagine billions of shots have been fired in guns joined similar to this one with no ill effects and we can only guess the pressures many have digested without even a burp. Millions of guns were made this way. So, I’m going to say time has proven it to be safe. I keep looking at that dark area in the break up about 1 1/4” forward of the breech. I agree with others, it is dark and not consistent with the rest of the fracture. Could have been a crack that went unnoticed until it let loose with an exclamation point!

I'd also say it looks scary how thinned the barrel looks around the rib. There may be some ring bulge present, but it has the look like the chamber hinged outward with the pivot point around the right side of the extractor notch. Note to myself, take a look in the chamber towards the midline, my feeling is that dark spot would have looked suspicious without much effort. Thanks Doc Drew for presenting the incident, doing the digging, and explaining the possible rib extension construction that's hidden from view. Will be watching for updates.

I'd edit to add, that even though it may have been a common construction technique, it certainly has the look like it breaks the classic rules of barrel thickness for the location. It could have been exaggerated by chamber work, but it still leaves the possibility of relative thinness combined with potentially higher corrosion risk in the same general area. Only thoughts.

I agree about the dark area. It may have been compromised for some time.

The chamber doesn't surprise me at all. I've seen many original chambers with tool marks. One Sterlingworth had identical grooves in both chambers from a burr on the chambering reamer and those chambers were original 2 5/8ths. The low angle at which we view the chambers when looking in the barrel makes them look smooth. Even when they are not.

There may be very little to no displacement of the rib, and it does not appear to have burst 6 to 12 inches down the barrel as Doc Drew had mentioned in the "How much barrel obstruction" thread.

Possibly the braze failed allowing the lateral wall to "tin can" open? Obviously the barrel flats are very thick.




A 10g Parker felt to have a base wad obstruction with an asymmetric 'ring bulge' related to the addition thickness of the brazed barrel flats

A detonation. Always use best quality ammo.

Give Ted a cigar for being the first to note how thin the chamber wall is.

Give 775 a cigar for expounding upon that observation with more detail about the very thin area under the rib, and the dark spot where the big rip probably started.

I wonder if the owner of these barrels realizes that the guy he sent them to for analysis of the rupture is absolutely unqualified to make a determination of cause for this blow-up. Seriously, this is someone who was arguing several weeks ago that chamber lengthening in vintage doubles could result in GREATER WALL THICKNESS at the end of the recut chambers. It took a couple days with drawings and detailed explanations of the obvious to convince him otherwise. I'm pretty sure just mentioning this little detail will be used as evidence that I have acid and hate in my soul. Should be good for a Scripture verse or two. Maybe even a picture of Guatemalan kids or a dead dog.

There is no evidence that a "Detonation" occurred here. Detonation in the chamber of a gun would simply shatter it into smithereens. Detonations occur in High Explosives, not ordinary Smokeless Propellants.

"Detonation" can occur when a smokeless propellant is used in a manner not suitable for the application. Detonation with smokeless is hard to "pin down", but usually occurs when a small charge of slow burning propellant is used in a case that allows a lot of empty space where the propellant is housed, like a centerfire rifle case ............. not likely with a shotshell.

SRH

It appears to me that pressure sufficient to cause this failure was applied to the full length of the chamber.

The entire right side of the chamber is bulged out and levered by the flats where a crease is evident.

This one has a different look to it than some others we've seen here.

re: detonation
Short version
Detonation of smokeless shotgun powder HAS been demonstrated experimentally
Detonation of smokeless shotgun powder in a shotshell have NOT been demonstrated
Long version
http://www.trapshooters.com/threads/smokeless-powder-ddt.245629/

IMHO this is the result of detonation. The remains of a Perazzi MX8

re: 20 in a 12 burst. This may have been one. Long aneurysmal bulge with burst and burst forward of the obstruction



re: expertise. It doesn't take a lot of brains or talent to record wall thickness numbers; just the equipment and practice therewith to establish repeatable numbers and the willingness to spend the time to do it right; and it does take time.

Correct- in most cases, and overloaded shell can be the culprit- RWTF

I recall reading about all those big magnum rifles which could be loaded with a compressed charge of a slow burning powder such as 1831 which was very popular in that era. Then it seems some folks wanted a reduced load so as this was then a surplus powder & available at extremely attractive they just cut back & loaded about a half charge. Most of the time everything went OK but on occasion, one would get a blown up gun. A lot of p[eop;e started hollering Detonation from all the exposure of the charge to the primer flash. Ballistics labs could not reproduce any high pressures at all & some went so far as to say this simply could not occur & had to be from some other cause rather than loading the light charge.

Rifles, however, continued to blow up. Investigation finally proved it was actually a failure of the slow burning powder to properly ignite with the primer force pushing the bullet into the bore & when the powder then caught the bullet itself acted as an obstruction. To the best of my knowledge, it was proven beyond doubt none of these bursts had been due to detonation.

Many feel that a lot of the early burst shotgun barrels when the switch to smokeless came in was from a similar cause. It took a while to realize the primers which were successfully used with black were simply not sufficiently hot to ignite smokeless resulting in an ignition lag. Damascus, of course,
became the ScapeGoat.

So yes under some conditions it is possible to get a "Detonation" with smokeless pro[pellant, but I would have virtually no concern of it happening inside a gun barrel. Plus like I said a detonation would not have just split the chamber, it would have made shrapnel out of it. With a true detonation, there is no such thing as a slow burn or fast burn, the entire charge simply GOES as one. It needs neither a projectile in front nor an overcharge to totally shatter the chamber. This is NOT the condition I am seeing in this gun.

Miller,
I seem to recall that the researchers could get a detonation out of a shotgun with an old, factory loaded shell that had been exposed to a lot of vibration, such as rattling around in a cars glove box for years, and then being used. The theory was the powder broke down into dust, which, then acted as an explosive, rather than a propellant.
Looking at that pizza gun give me the willies.


Best,
Ted

Believe what you want, but a detonation is an entirely different thing than excess pressure, which is quite easy to see occurring under the circumstances you mention. Many, Many times the word Detonation is used incorrectly to describe what is not truly a detonation at all.

Sometimes "UNEXPLAINED STUFF" just happens. It seems unlikely we will never truly know what caused this shotgun malfunction. We can postulate, presume, and suppose - but will never be sure. Thankfully, no one was hurt.

When used in explosive devices, the main cause of damage from a detonation is the supersonic blast front (a powerful shock wave) in the surrounding area. This is a significant distinction from deflagrations where the exothermic wave is subsonic and maximum pressures are at most one eighth[citation needed] as great. Therefore, detonation is a feature for destructive purpose while deflagration is favored for the acceleration of firearms' projectiles. However, detonation waves may also be used for less destructive purposes, including deposition of coatings to a surface[25] or cleaning of equipment (e.g. slag removal[26]) and even explosively welding together metals that would otherwise fail to fuse. Pulse detonation engines use the detonation wave for aerospace propulsion.[27] The first flight of an aircraft powered by a pulse detonation engine took place at the Mojave Air & Space Port on January 31, 2008.[28]

So very often we hear a very rapid Deflagration described as a Detonation, but they are Horses of Two different colors or Apples & Oranges, however, one prefers to put it. Purely & simply the charge in this gun in question did not detonate.

OK. So a pipe bomb loaded with Green Dot doesnt actually detonate?

If shot leaves the barrel at or above but 1150 fps, is it a detonation? I've read the definition of detonation before, but cannot reconcile it with ballistics or ammunition without incorporating a few other assumptions that may be wrong.

Interesting that the rib is separated well ahead of the chamber and damage area.







I also agree that the fault seems to be the thin chamber area with blackened edges just under the rib extension. That looks like it has leaked for quite some time, resulting in corrosion, and ultimately this burst.

Curl

Not in the same sense as a high explosive would detonate, John. The difference is burn rate, high explosive usually considered to burn at a minimum of 3,000 meters per second. The deflagration you typically get from a propellant, like smokeless powder, is the result of a slower burn rate. Typically slower than the speed of sound. So while a pipe bomb appropriately packed with smokeless powder, especially if ignited by something that will give it a significant jolt (like a primer in a shell, or a blasting cap in a pipe bomb) will make a pretty impressive "boom!", it will be a much less violent blast than if the pipe bomb contained even a smaller quantity of a high explosive, like C-4--which burns at a much faster rate. As Miller points out, detonation (high explosive) vs deflagration (low explosive).

On the picture showing the chamber, what happened to the rest of the metal to where it shows nothing and then shows that area twice the thickness.
It looks like whomever did the chamber lengthening, really screwed up by not centering the cutter to the bore. And why would you take anything out that close to the breech when that dimension should have been ok.
All chambers were .014 in 2 3/4". The forcing cone is 1/2" then to bore which for that year would be .650

If this gun was sent from the factory with 2 3/4" chambers it would have 2 3/4 Inches in an oval circle on the right barrel flat. With the way that chamber looks, that was not done at the factory.
Brother Drew, when you get those barrels I would measure the chamber diameter in the left barrel and it should be .745.

Unless I am missing something, that chamber was egg shaped before this happened.

Gentlemen,

When having the Chambers opened up on an L.C. Smith double gun, it is advised that you have a Master Gun Maker do the job, somebody like Freddie Brunner or Rich Painter.

This looks like a Chamber that was not opened properly, causing failure after repeated usage. Left alone at 2 9/16" the gun would have had no problem.

Pine Creek/Dave
L.C. Smith Man

Did they ream out the chamber at the same time they altered the forcing cone area or is that a normally thin area that just gave it up over time? I think that is a thin area that got a small crack in it, then got weaker over time as the crack got longer or the entire chamber area became separated.

I had a Fox 20 which had a small split area on the left barrel that vented into the space between the ribs. Barrels had been cut and they never sealed the end back up so moisture got into the area between the ribs. Over time it became a split that vented gasses. I noticed it when I was going to fill in the space between the barrels for a rust rebluing. 20" from the chamber area it made no real difference to me. It was ported into the space between the barrels and ribs. Had that been in between the chamber I could see it blowing up just like this gun did. Rust is a very bad thing for guns.
.

I appreciate everyone's (well not quite everyone) thoughts. This is a close up of the area in question. It is unfortunate that the missing chunk of barrel could not be found

I find it hard to believe that Hunter Arms Co. would pass the barrel in question with that thin of a wall in that area. It is also hard to judge how far back the thin wall is compared to the heaver wall down from it. At this point it would start to curve up but if the heavier wall was say .150, the thin area looks to be half of that and would definitely not pass their inspection.
Back then Hunter Arms proof tested their guns with twice the powder that was used back then. There were no proof marks stamped on the flats until the 1920's.
Also the groove that looks to be even with the extractor down from the breech would not be from the company.
Be interesting in what is found in the left barrel.

I do not think the chambers were oval prior to blowing. If so, the fired shells that Drew got with the gun should bear that out, but I'll bet against it.

I also do not think chamber lengthening was involved either. That chamber blew too far back, and was too thin from the day it rolled out the door. The solder behind it does not look too well done either, so if there was a bit of void in places, that would be a spot where pressures would work the steel, perhaps creating a crack where the darkened area of the break is. From there some corrosion or just more time and fatigue and eventually, it had to let go.

In any event, I think this gun was doomed when it was born.

It would be interesting to section the left barrel in the area where the walls are so thin on the right. Any chance that could be done?

OK, that makes sense. Sematics aside, somehow that chamer, and shell exploded. I suspect that dark area inicates corrosion that weakened the area. Add to that a ammo quality and 19th century design specs, boom.

Drew, can you see the solder joint on the left side? From viewing the right, it appears that you may be able to visually see how thick it is directly from the rear.

I agree with BrentD. I think there's a good possibility that the chambers are original. I don't think most people realize how rough chambers can be on these old guns. And how would they know about, or measure that thin wall, in a manufacturing environment of 100 years ago?Maybe the barrel sets were chambered after the barrels were joined up. Does anyone really know the sequence of assembly that Smith used? I think they probably were built that way and finally gave up. That gun lasted a lot longer than the manufacturer probably intended. I think Gunmakers would be amazed that were still shooting these things 80 to 140 years later. This event is also a good reminder to stick to low pressure loads if at all possible. Anyone of us could have hidden defects in one of our old treasures.

We'll hopefully know a lot more when the barrels arrive.

To be clear, the wedge shaped top rib extension and hook are brazed to the barrels. See the images on p. 1. The joined metals have a very strong bond ie. a mono-metal, and the top wedge and bottom wedge should be considered as contributing to the barrel wall strength.

METL charges about $1000 for a formal Failure Analysis. Sectioning of the barrel and examination with photomicroscopy alone could be performed.

When discussing barrels alone, properly designed and manufactured barrels, of the correct steel for the application, free of defects or corrosion, used with loads for which they were designed and proved (by the maker in the U.S.), have an indefinite lifetime. Unfortunately, bad things happen to barrels in 110 years of use, abuse, and inexpert barrelsmithing.

The hang tag that came on that gun listed 2 1/2 dram 1 oz. shot, and Nitro powder loads then had similar pressures as today. And again, this is in reference to the barrels, not the wood or internal parts which do indeed wear, and wear out.

If it comes to that, I will ante up.

But it is so much more fun to make definitive diagnoses with the least amount of data...

In the meantime, the rib extension to barrel bond looks anything but very strong. How much is corrosion vs. just a poor job, I can only guess.

Thank you JHJ. We'll take it one step at a time.
Metallurgical testing labs make the big $s diagnosing pipeline blow-outs and airplanes falling from the sky. It is possible that one of the METL engineer could perform one stereo macroscopic examination and explain with some certainty what happened just for the cost of a consultation fee.

Miller, the word that has been used in reloading literature for decades, when referring to a reduced charge of slow burning powder in a large capacity case that causes damage, is detonation. You may not agree with the terminology, but that is the term that has been used to describe it for ages. It may be an incorrect usage of the word, but it is what has been used for as long as I can remember to describe the event.

So, your issue should be not as much with our usage of it as much as with the original writers who coined the phrase. We're just ignorant enough to continue with it.

SRH

So just what do you think the missing piece could tell us that the photo of the very thin section doesn't already show?

It is highly doubtful that a chamber lengthening reamer would have enough lateral force exerted on it during a minor lengthening process, to create the thin area.

Since there is no other pitting or corrosion apparent in the remains of the chamber, it is highly unlikely rust or corrosion was involved. More likely... The chamber was probably thin from the beginning, and that thin area just happened to include a small inclusion of rolled-in scale. It happens, and should be a stark reminder that our fluid steel isn't necessarily homogeneous and free of internal defects, just because we can't see them. Even the best steel mills in the world, with excellent quality control, sometimes make scrap. Sometimes that scrap makes it out the door. Metallurgical testing of the remaining 99.9% of this blown barrel might not reveal another hidden defect.

It seems apparent that there was also some prior leakage of powder gasses due to this combination of defects, and that was causing a separation of the rib braze joint. When enough surface area of the braze joint was compromised, it finally let loose. It seems unlikely this barrel was ever proofed with a double the normal pressure load, or it probably would never have made it out the factory door. But it is likely the braze joint added enough strength to this thin area for all these years to contain normal chamber pressures. The tensile strength of a good braze joint can approach the strength of a welded joint. I think that short section of rib was essentially a patch over a thin and defective area that finally failed.

There might be a fair chance that something was machined out of round, the groove for the rim of the shell does not look uniform. Any old pictures of the chambering setup during manufacture? If the rim recess was cut with the chamber reamer, some other secondary machining very well may have been done in there.

Still, I'd think that if there're signs of pitting in the chamber towards the rib, one might wonder if the hoop strength in the area is affected, knowing it starts off relatively thinner.

why not just measure the barrel wall thickness of both barrels in front of the chambers and post that data here?

Great idea Ed. Since the Preacher argued several weeks ago that chamber lengthening in vintage doubles could result in GREATER WALL THICKNESS at the end of the recut chambers, maybe they got so thick that it actually created an obstruction!

Sheesh! Maybe we should all donate to collect $1000.00 for failure analysis, and continue to make a mountain out of a mole-hill, when the cause of the burst is pretty apparent.

I think it's reasonable to guess that the defect progressed, fresh broken steel or brazing would be bright.

I wouldn't think this is propellant gase damage or coloration. The location would seem to indicate that a hull would seal against the chamber wall. This pit, or defect, or inclusion would have had to have been past the 2 3/4 in. hull length. Also, I'd think if gases came back along the rib extension stub like the darkness suggests, the shooter might see fouling on the breech face and rib extension.

Stan;
With all due respect that's not the way, I read it. When this phenomenon first began appearing many "Suspected" detonation. It was ultimately "Proven" that it was not a detonation, but indeed was a pressure spike from an obstruction, the bullet being fired is the obstruction.

The only difference in this from sticking the muzzle of a shotgun in the mud & firing it, thus blowing the end of the barrel off is in the latter case the powder has all been burned, though the gas is still expanding. In the case of the rifle, it occurs so near the breech that the powder is still burning as well as the gas expanding. In Neither case though does a detonation occur.

I simply Refuse to use the Wrong term when I "KNOW" it is wrong as that only serves to propagate the Error..

Edited quote from BrentD




Think you hit the nail on the head, why ream out a chamber, also just looking, but the tear appears to be angled, I would be surprised if when measured the walls are as thin as they look!

Stan, the Army originally trained me as a Combat Engineer. Specifically, a Combat Demolition Specialist. But that was over 50 years ago, and I had to dredge up very old memories and then confirm them with a bit of research (and a big hint from Miller when he used the term "deflagration"). Because ammunition doesn't use a high explosive as a propellant--which is a very good thing for all of us!--it never really detonates. But used in ways it was never intended to be used--like in a pipe bomb--smokeless powder will certainly explode. That term applies accurately to powder just as much as it does to TNT, dynamite, C-4, Composition B, etc--all of which have explosive properties. We don't normally talk about an explosion in reference to ammunition fired in a gun, but in fact--smokeless powder being a low explosive--that would be a more accurate term than detonation, which is a term that differentiates high explosives from low explosives.

But I doubt we're going to end up using English more accurately regarding ammunition, because we've all been using it inaccurately for far too long.

I respect your constant diligence to use the correct terminology, Miller, but in today's world you may be tilting at windmills. It simply doesn't bother me when a word or phrase has taken on "a life of it's own", and the rest of the world completely understands the intended meaning of it.

While were at it, tho' ............ I imagine you don't much like the word "detonation" used in this regard, either. Gasoline doesn't really explode either, does it? it burns. If it actually did detonate, I expect it would blow the engine, as you say, to "smithereens". But, the most highly technical researchers and test labs use the word to describe this phenomenon that takes place inside the combustion chamber of an internal combustion engine.

https://www.enginelogics.com/engine-detonation/

All my best, SRH

I assume the shells used will be tested for pressure.

Here is another idea for consideration. When the barrels were assembled into a bundle for brazing together, the barrels had "flats" filed on the sides, where they came into contact with the top and bottom wedges/rib extensions. When a close fit was achieved, everything was cleaned and wired together with flux and brazing material in the joints. Then they were heated until the brazing material flows. Sometimes the bundles were heated until they "glowed". If one of the flats on a barrel was filed too thin, itself a problem, the too thin section would be more likely to "burn" in heating the bundle. After assembly, this couldn't be seen by an inspector and if it passed proof, it would be passed to the public. One proof load doesn't always show a defect, sometimes it takes repeated "shocks". Rechambering the gun is not what caused the incident.
Mike

Thank you Mike, and good thinking.

Yes, I will receive some unfired shells from the same box and intend to send them for ballistic testing.

ed: I don't have the barrels yet.

re: the missing chunk. This is the blown out segment from the 2014 study



It would seem obvious that actually measuring the wall thickness of the edges, esp. the medial formerly brazed edge (numbers are good; eyes fool us) might be of worth. And preparation of the edges for photomicrographs by the metallurgical engineer at METL is much easier using the chunk than cutting up the remains of the barrel.

Arrogance is a dangerous thing. One tends to make a presumptive diagnosis, then seek data to confirm that presumption, and discount or ignore data contrary to that presumption. In medicine, it gets patients killed BTW.

And since William seems intent on turning this (once again) thread into his personal toddler wading pool of filth and an opportunity to continue our feud, and since it is my time and money, of which I have, I'll choose to do what it takes to arrive at a reasonable conclusion as to the cause of the blow-out, and just maybe we can learn something. What a concept!

This might be helpful. A 1906 00 12g and the rib extension braze line is quite apparent. The hook line is more difficult to see in the image, but apparent visually



Clearly the superior-medial barrel that was ground flat is much thinner, but again, because of the strength of the (correctly performed) braze, the "wall thickness" includes the wedge.

The key words being "correctly performed". I have my doubts.

I think that the gun managed for so many years would seem to indicate that the braze connection was within an acceptable range, which would include the temperature to perform the braze. I don't think these incidents are design or execution problems, but more likely exceeding an intended limit or changes that had subsequently happened.

Perhaps it was simply metal fatigue. Higher pressure modern ammo, causing imperceptable expansion and retraction on each shot, exacerbated by the failure point (dark spot). 100 years and thousands of iterations, she finally let go. (^contraction)

If that is the scenario, the Energy Dispersive X-ray (EDX) scanning photomicrograph of the fracture edge would look something like this: from left to right low cycle ductile fatigue "waves in the sand" or "beach marks", then plastic deformation (stretching) "fish eyes", and then terminal cleavage



If an extreme pressure over-load burst there would be no "waves in the sand"

Now then, if you were to include the pre existing condition of a large area of corrosion, how would this play out?

At some point the pressure found bursting the chamber an easier route than the, or what once was, that huge "16ga tunnel" it had been using for 100 years.

Porosity spot on the dark area.

I am in agreement with 775. There was a pre-existing crack/break, where the barrel was milled for the barrel extension, at midchamber. That point is clearly shown in the picture as having previous corrosion while the rest of the fracture surface is fresh metal. This, in my opinion, is the root cause. Whether there was an obstruction to speed it along is to be determined. That missing chunk of chamber would be nice to evaluate.

John

John, it certainly would be nice to see the outer surface of the missing piece. Somehow it let go along the braze joint, so either it was a bad braze or there was corrosion - at least that makes some sense to me given what we have seen so far. I think the dark spot on the break would be confirmed on the other piece as well. I think this gun was doomed at birth, but we may never know.

Now, that's no way to talk about the Preacher and his thin skinned sensitivity over someone retaliating for his prior personal attacks. Seems like Drew can dish it out, but he can't take it. He should have thought about that beforehand. But it's easier for him to cry and play the victim.

I still wonder what good accurate wall thickness measurements are for someone like Drew, who actually thought that chamber lengthening would result in GREATER WALL THICKNESS at the end of the recut chambers??? All the measuring instruments in the world are just wasted on someone who isn't smart enough to interpret the data. But if you copy and paste enough photomicrographs and stuff from sources who really are knowledgeable, you might fool people into thinking you are a big-time expert in metallurgy or barrel burst analysis.

Sherman Bell didn't need Metl or any other Metallurgical testing firm to tell him that it was excessive pressure which caused the bursts in his Damascus barrels... or that the barrels finally let loose at the thinnest and presumably weakest point. Heaven forbid we should simply rely on common sense and things that are plain to see.

That does appear to be where the initial fracture took place. Similar in that respect to the gun Bell subjected to gross overpressure (load in excess of 30,000 psi, if my memory serves). It blew out from the void between the barrels where the extractor rod rides. An obvious "weak point"--but not very weak in that gun (a vintage Parker), given that it took that much pressure to result in a catastrophic failure.

The only failure I've had a chance to look at (a few minutes after it happened) similarly started at a weak point. The gun in question was a Fox, which has slender rods (or guide pins?) on the outside of the extractor, riding in channels just below each barrel. A friend, looking at the gun with its blown right chamber, pointed to the void where the pin rides, thinking it was a flaw in the metal. And it very clearly blew from the outer edge of the barrel inwards, toward the rib, rather than from between the barrels out. Just part of that particular gun's design, but also an area which is weaker, thus vulnerable to failure if there is significant overpressure in the breech area.

Ah William. Once again the blind hatred is making you appear the fool.
In the hope of learning something 2 of the barrels used by Sherman Bell, with the technical support of Tom Armbrust, and published in The Double Gun Journal Vol. 10, Issue 4, Winter, 1999, “Finding Out For Myself” Part II and Vol. 16, Issue 2, Summer 2005, “Finding Out For Myself” Part IX were given to the pseudonymous Zircon, a metallurgical engineer, who posted “Contribute Junk To Advance Barrel Strength Knowledge” on two public internet forums in 2005 requesting vintage barrels for composition and strength testing. By 2006 he had accumulated almost 40 samples, both Fluid Steel and Pattern Welded. Part of the collection included the Damascus barrels from the Parker GH and the Vulcan Steel barrels from the Parker VH that had been the subjects of Bell's destructive testing.
Both guns were subjected to sequentially higher pressure loads at about 2,000 pounds/square inch (psi) increments. The GH testing started at 11,900 psi and one chamber ruptured at 29,620 psi. The VH started with a Proof Load of 18,560 psi. Both chambers bulged at 29,620 psi and ruptured at 31,620 psi.

A formal Failure Analysis was proved to the BOD of the PGCA, with photomicrographs and Energy Dispersive X-ray (EDX) Scanning Electron Micrographs, but to my knowledge it has not been published.
A partial report was placed on a Public Domain forum, and is worth reading
http://www.familyfriendsfirearms.com/forum/archive/index.php/t-55364.html
The mode of failure of the barrels is not necessarily applicable to our subject barrel since the failures were induced by higher and higher pressure loads, but the fluid steel barrel failed by abrupt brittle rupture, and the damascus barrel by low cycle fatigue with ultimate ductile fracture.

and what Larry said
"On the two old Parker barrels, there is a screw hole that comes up from the bottom and pins the extractors in place. Both barrels failed at that hole, because it takes a (segment) out of the side of the chamber and is the thinnest portion of the chambered area."

I communicated with Zircon in February 2008 regarding his Analysis, then again in 2015. He still had the barrel samples and intended to do composition and tensile strength testing, and also intended to submit his Failure Analysis on the Parker barrels for publication.

"Things that are plain to see" commonly are not what they appear to be, and we all "see" what we want to see.

BTW: have you purchased a wall thickness gauge yet? Looking forward to a bunch of end-of-the-chamber numbers for our knowledge base.

The "porosity spot" might look like this; corrosion stress micro-fractures

This Parker chamber blow-out was presumed to start at the screw hole and extractor guide channel
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=491058&page=5



And the point of a failure analysis is to avoid the same, which Savage must have missed. As of 2018, lawsuits related to the Savage 10ML II (designed for use with Smokeless Powder) with Crucible 416R Chromium Stainless Steel barrels were ongoing. It is alleged that catastrophic barrel failures have been the result of both a design flaw (screw hole) and a metallurgical flaw (manganese sulfide inclusions in the 416R)
https://cases.justia.com/federal/appellate-courts/ca6/12-1475/12-1475-2013-08-09.pdf?ts=1411028258

So, it seems this site is populated with a plethora of metalurgists, ballesticians and other experts. I spent 35 years as a Field Service Engineer, as a front line troubleshooter. So I still ask, why did the pressure change direction? What changed after 10000 firings? Has anyone else noticed the hull case mouth isnt even close to normally opened?

I suggest a combination of garbage ammo and a seriously weakened chamber, over time, resulted in this failure. If one is to own such a shotgun, then use proper ammo.

Maybe I'm not looking at the same hull as you, but I don't see anything abnormal about the mouth of the hull.
Pete

The crimp appears to be straightened out as if fired, but certainly damaged in a way that might reflect the way the barrel is damaged. Do you see signs that the shot and wad ejected laterally out of the barrel damage opening?

Having loaded over 100,000 shotshells, that hull didnt open properly.

ok andy

If the chamber let go before the wads and shot went up the bore what would you expect to see. An incompletely opened hull or what remains of one.

Unless when they cut this hul opened and damaged the inner base wad, is does not look right and I said that from the beginning. It will be interesting to see when Brother Drew gets the empty hulls to see if one is missing the inner base wad.

That information from the Sherman Bell experiments is all old news Drew, and repeating it again still won't make you any brighter. Neither will the use of big words that you probably don't understand.

I don't know why you are hung up on the fact that I haven't given you any wall thickness measurements from barrels which have had their chambers lengthened???... aside from your childish and insecure need to attempt to discredit me. Miller and I spent considerable time trying to explain that YOUR assertion that chamber lengthening in vintage doubles could result in GREATER WALL THICKNESS at the end of the recut chambers was wrong. Miller even gave you a picture to simplify it, but you still didn't want to accept the obvious.

That should have told everyone here what is glaringly obvious to me. You are not a shotgun barrel expert, and you don't have what it takes to ever get there. Copy-and-Paste regurgitation of other people's work and metallurgical terms isn't going to change that. And all the measuring instruments in the world are not going to change that either. Nor will contacting Zircon again.

And your decision to launch your personal attacks on me over the last couple years insures that I'll continue to remind everyone what a dim-witted phoney you are. I'm guessing that isn't the "eternal significance" you spoke of in your "Down One" personal attack thread. I'm not sure why you call me William. I have been called Keith since I was an infant. But if that makes you and your friend SKB feel like more of a man... then by all means keep on doing it... You both need all the help you can get. Have a nice day.

Not enjoying being treated how you treat others Billie? I find that incredibly amusing.

Speaking of not being smart, you are the only board member that I know of that has admitted to criminal conduct on an open forum. Now that is DUMB, but quite possibly just another of your innumerable lies.



Did the other shoe ever drop?

Care to share any of the evidence you claim(a total lie) to have about me being involved in a conspiracy to silence you?

Looks like beautiful weather in your part of Pennsylvania today Bill, maybe get out and get yourself some fresh air.


Have a great day.
Steve

This is my 16g Regular frame Smith, and the braze joint was much more difficult to demonstrate in an image



It is apparent that the filed flat superior-medial wall where it abuts the top rib extension wedge is much thinner than the rest of the barrel. That is of course not to exclude the possibility of a failure in the braze joint.

Drew, given the way the barrel burst, I think it is fair to say that the braze failed. It may have been do to some corrosion, or something else, but if the braze was as strong as the steel, it would have failed elsewhere, or not failed at all.

That would be good braze, that was as strong as the steel. You know that isn’t possible, right?

Smith’s were built with a corrosive flux used at barrel assembly. If corrosion led into the chamber, and allowed combustion gasses into the area between the rib and the tubes, that might explain what we are seeing in the black area. It also might explain why it looks like a 12/28 burst, without a clearly defined ring bulge.
The chamber wall appears thinner, from what I can see in an internet photo, then can be explained by stretch to elastic yield, but, it is only an internet photo, so far.
But, it is the most worrisome thing I can see.

Best,
Ted

Well, now we hear from SKB, the Official State Fruit of Colorado. Hi Stevie, I see you are still upset about me confronting your gay little friend Shortshells. Since you keep accusing me of admitting to criminal behavior, why don't you just notify law enforcement already?

Actually, one of your Liberal pals really did admit to criminal behavior here. That was King Brown, who publicly admitted to illegally crossing the U.S.-Canada border several times with a pistol in his airplane. But I'll bet you don't think that was stupid or wrong, because King shares your Liberal Left Democrat mindset.

I'm not at all concerned about the personal attacks that came from your other Closet Libtard friend Drew. I was simply responding to his crybaby complaining, when he was the one who thought it would be a grand idea to initiate our little feud. I guess he though he is above getting hit back.

So anyhow, do you think the Preacher will chastise you for taking his "Mountain-Out-Of-Molehill" barrel burst thread into the weeds? I kinda doubt it, because as I observed, you Libtards all stick together, and are very selective about the things you all whine about.

Hey, do you plan to post anymore links from known anti-gunners like Peter Philips and Gunpolicy.org to support new anti-gun legislation... or to cover your lies claiming no guns are registered in New Zealand? That was something that most gunsmiths would never do. Well, gunsmiths who have brains anyway.

You have a nice day too Stevie.

Was the flux Smith used to Braze the breech assembly any different than other makers used for the same purpose? If so what flux did Each Maker use.

The two main fluxes for a solder joint are an acid flux & a resin flux. To the best of my knowledge, neither of these were used for Brazing.

Lies, Lies and more Lies. It is what you do Billie.

On the NZ debate you stated that in spite of gun registration the attack in NZ happened. I replied guns are not registered in NZ and then clarified that 3% of them were registered at the time of the attack and posted a link to a NY Post article stating the same. I never posted a link to Gunpolicy.org. If you have another source showing a higher registration rate please post it Bill.

Did you just admit to your criminal behavior?

Any evidence of the conspiracy you claim that I am involved in trying to silence your nonsensical blathering?

Have a nice day Billie. You are fooling no one with your LIES.
Steve