SEE, Big Bang

[joeb33050]

Big bangs are reported with small charges of slow burning powders, sometimes blowing up the gun.
This happens infrequently and appears to be non-reproducible and is explained in great detail by theorists. (Some similarities to the chamber-ringing phenomenon.)
I'm starting to have enough powder measure bridging events documented to see that it is entirely possible to drop too much powder in one case out of a lot of many.
(Please, check your charged cases with a flashlight!)
So, I'm beginning to suspect that this small-charge phenomenon may be really a large-charge phenomenon caused by powder bridging in the measure.
I'm sure that opinions abound, has anyone any evidence to counter this theory/explanation?
joe b.

[Char-Gar]

I always peek inside the case with a flashlight. As mentioned in the other thread, I have never experience briding, but I have found an empty case or two. Thankfully I have never found a double charge.

Years ago I read an article by Kent Bellah. He made a powder column gage by cutting off a No. 2 pencil, sticking it in the case on top of the power and marking the pencil where it exited the case mouth. He would place this pencil gage in the charged case to check for uniformity. This is more accurate than the eyeball, but the eyeball can catch serous charge errors.

[felix]

Yeah, I use the pencil trick quite often, especially when trying to maximize the height of the powder for a specific boolit seating depth, leaving just a smite of breathing room for primer flame expansion. I don't like to crush powder, and barely do so when necessary by keeping any filler used (poly type preferred) in place. ... felix

[Shepherd2]

I've had many instances of bridging with my RCBS Uniflow over the years. More than once I've thrown a charge and put that case in the tray and on the next case had the powder overflow the case when the bridged powder let go. I can see where joeb is coming from with the small charge really being a big charge.

I use the pencil method sometimes and use a flashlight everytime. Heck, I even use the flashlight when I've trickled the charges to get the final weight.

[fourarmed]

SR-4759 is about the worst one to bridge that I have used, but any of the big stick extruded powders will do it occasionally. I put my cases in a loading block and charge them by holding the block under the measure. I charge the cases in order: down one row and back the next. Then I pull down my magnifier lamp and look in each one. If bridging occurs, one case will be low on powder, and the case next to it will have extra. This enlarged difference is easy to spot.

I don't know what causes the occasional blowups blamed on SEE. With very slow powders, it probably isn't overcharging. You can't get enough of it the case in most calibers. With faster powders, I'd bet Joe is right.

[9.3X62AL]

Interesting theory, Joe.

My experience with the RCBS Duo-Measure has been like Chargar's--a few short feeds from time to time, so I either use the loading blocks and a flashlight or limit myself to ball and short-cut stick powders when the measure is used on the P-W pistol machine. There's enough agitation by the mechanism on the P-W to guard against bridging, and using powders that flow smoothly is another step in the direction of consistency.

[Larry Gibson]

joeb33050

"Big bangs are reported with small charges of slow burning powders, sometimes blowing up the gun. This happens infrequently and appears to be non-reproducible and is explained in great detail by theorists. (Some similarities to the chamber-ringing phenomenon."

Not so, S.E.E (Secondary Explosion Effect) is no longer theory and has been reproduced in laboratories. Below is an article that appeared some years ago in Handloader explaining S.E.E. Thought you and others might be interested in it. I will have to make two or three posts to get it all in.

Larry Gibson

Handloader- readers have doubtless heard of a term called secondary explosion effect (S.E.E.). It is a theory that attempts to explain the catastrophic failure of some rifles while firing seemingly reasonable handloads or reduced loads using slow-burning powders. Theories have been offered and debated in these pages and elsewhere, but they have been just that, theories, because no one has been able to reproduce effects under laboratory conditions. The purpose here is not to debate S.E.E. but rather to report on a specific incident and the results of tests done to discover the cause of catastrophic failure.

One of the great problems with attempting to theorize on the cause of catastrophic failures is that we must do so after the fact. We have the corpse, usually with some parts missing and must try to figure out what went wrong. Learned theories are offered, sometimes conflicting, and we end up with a bunch of folks shouting in print, 'You're wrong.' "No, you’re wrong." Since the event they're arguing about what without benefit of instrumentation, either one could be right. The events I describe here represent the first instance of an event produced under controlled laboratory conditions and documented on industry standard pressure measuring equipment that provides a plausible explanation offered to explain S.E.E.

The following is simple. It goes all the way back to Shooting 101 where we learned that bore obstructions blow up guns. There are no explosions, no mysterious wave amplifications; it's just a case of several factors, combining in worst case conditions to create a bore obstruction with the bullet.

In early 1989 a major manufacturer began development of a load for the 6.5x55mm Swedish that was to be added to their product line. Development was uneventful and all work was done using the copper crusher pressure measuring system, for there were no standards established for piezo-electric pressure measurement in the 6.5x55mm. The copper crusher method of pressure measurement has been with us for generations, but it is not without its limitations. The results obtained are not true "maximum" pressures, and it provides only a single data point. There is no way that one can deduce what is happening during the period the powder is burning, nor can one see other significant ballistic events.

A quantity of ammunition was loaded using a relatively slow-burning, non-canister propellant with a 140-grain bullet. After load development in ammunition manufacturer’s pressure guns, it is common practice to function test ammunition in a variety of available rifles to ensure satisfactory performance before it is released for sale to the public.

As function testing of the 6.5x55mm ammunition was begun using Swedish Mauser rifles, they noticed some of the same signs of excess pressure every handloader is taught. to look for - flattened primers, enlarged primer pockets and heavy bolt lift. All the ammunition fired in the pressure gun had been perfectly acceptable, but SAAMI test barrels and chambers are made to tightly controlled specifications so the first supposition was that some element within the test gun was contributing to high pressures. Then a "spontaneous disassembly" occurred that destroyed the action but left the barrel undamaged. The bore was clear and showed no bulges. It was immediately identified as a high pressures failure and an investigation was begun. The barrel from the wrecked Mauser action was fitted with a collar that allowed it to be mounted in a universal receiver, and an industry standard conformal piezoelectric transducer was installed. Another test was performed using the Oehler Model 82 piezoelectric pressure measuring system equipped with a trace hold oscilloscope.

(Fig !)
round pressure (psi) velocity (fps)
1 48,820 2,601
2 53,849 2,662
3 57,609 2,708
4 57,999 2,720
5 54,093 2,687
6 58,634 2,731
7 62,150 2,754
8 82,120 2,875

Pressure tests are commonly done with a 10-round string and as you can see from the chart, pressures increased very gradually on rounds I through 4. At the fifth shot, pressure dropped and then continued to increase until, at the eighth shot, pressure, went to 82,120 psi; and the technician wisely stopped the test. The raw data was then used to prepare additional graphs (fig. 1) which show that, after ignition, pressures dropped momentarily to near zero on the graph before beginning to rise again.

[Larry Gibson]

S.E.E. continued.

To interpret this data we have to first understand the ground rules applicable to pressure testing with conformal transducers. The key term here is 'offset" which relates, primarily, to the specific cartridge and the brass used therein and must be determined for each transducer and lot of brass. The offset is the amount of pressure required to obturate the case to the chamber and begin to exert pressure upon the transducer. In this case the offset was 3,800 psi so when we look at the time/pressure curves produced in the test; we must understand that we are not actually seeing pressures below the level of the offset. There is a distinct dip in the curve, however, shortly after the pressure begins to rise when it drops to a level somewhere at or below the offset pressure. All we can say for sure is that, at this point, the pressure is <3,800 psi. Engineers calculated that for the specific bullet being used it would take pressure of at least 5,000 psi just to keep the bullet moving.

As I said, there are a number of variables at work here, but the main culprit is a very long leade or throat erosion. It takes relatively little pressure to eject the bullet from the cartridge case (de-bullet), which produces a significant increase in volume. Unless the rate of gas production is fast enough to keep up with the increase in volume, pressure must drop. The simple equation is PIVI=P2V' where P = pressure and V = volume. It is helpful in considering the phenomena reported here to view the rifle barrel and chamber as a cylinder whose volume is determined by the position of the bullet at any given point in time. If the bullet is moving, the volume is continuously increasing until the bullet exits the barrel.

If P2 is at or below the pressure required to keep the bullet moving it must stop. Then we run into our old friend inertia. Bodies at rest tend to remain at rest, but all the powder burning behind the resting bullet doesn't know about that. It keeps burning and pressure rises. Sometimes we get lucky and the bullet starts to move and relieve some of that pressure, but in a worst case of a rough bore and/or soft bullet it doesn't, and pressure continues to build until something else lets go. Most of the time this will occur around the primer pocket and gas will be released through the flash hole, but we're talking about events that are taking place quickly (milliseconds); and if pressure rises at a rate faster than it is being relieved, a catastrophic failure is inevitable It has been theorized that many 'accidents" represent a combination of effects which combine, in worst case conditions, to produce a catastrophic failure. Robert Greenleaf (Rifle No. 146) presents convincing evidence to show that conditions rarely remain the same, and the condition of the barrel and throat combined with different bullet characteristics can produce markedly different pressure levels for the same load. This is certainly seen in this data where a series of eight shots of the same ammunition delivered pressures ranging, and steadily increasing, from 48,820 psi up to 82,120 psi, at which point the test was stopped. We can, from looking at this test data, presume that all rounds (except perhaps the first) displayed some degree of temporary bore obstruction, but that the bullet was blown out of the barrel. Fortunately universal receivers are capable of containing considerable pressures, and it is certainly possible that the pressure generated by the last shot would have wrecked a standard rifle.

One factor that cannot be accurately measured with this data is the possible contribution of fouling from the bullet itself. It seems reasonable to assume that some accumulated fouling was blown out on the fourth shot, which accounts for the drop in pressure at shot No. 5.

When the engineers were able to examine and expand the time/pressure curves produced during this test, it became obvious that each shot showed a pronounced drop in pressure very early in the ignition/burning cycle and, on the shot where the pressure reached 82,120 psi, it dropped to the baseline before resuming a climb to the stratosphere. It would be easy to think that the fire went out, but a more reasonable explanation is that the burning rate of the powder became even slower. We know that pressure is a major component of the burning rate of any powder, and it depends upon adequate pressure levels being reached and maintained. In fact, what is shown in this case is that the amount of gas being generated was not sufficient to keep the bullet moving. If pressures drop below some optimum level, burning slows down and is often incomplete. Of course there will always be a quantity of unburned powder from any shot, and this observation has led to some of the conclusions regarding S.E.E.

[Larry Gibson]

In order for the pressure to rise to catastrophic proportions some other adverse conditions must also be present. These involve the cartridge case, the bullet, chamber and barrel and need to be discussed individually.

Bullet pull: We know that an adequate amount of tension between the case neck and bullet is a prerequisite for uniform combustion. This term, called bullet pull, is independent of the firearm and is routinely measured in the factories. Crimps may or may not be used to increase bullet pull, but most centerfire rifle cartridges depend primarily on tension between the case and bullet. If you've ever committed the sin of firing a cartridge into which you have neglected to dispense powder, you know that the primer alone is perfectly capable of propelling the bullet several inches down the barrel. Pressure generated by a primer alone can be as much as 4,000 psi in a conventional centerfire rifle cartridge; so it is certainly possible, in a normal round, for the primer impulse alone to be sufficient to get the bullet moving before little if any pressure has been generated by the powder charge.

Chamber: In the area of the case neck there must always be some clearance between the case and the chamber wall, but if this area is too large there is little resistance and the bullet can be released with very little pres sure behind it.

Condition of the barrel and throat: The impact of conditions within the chamber and throat are difficult for the handloader to analyze, and a throat that appears normal under cursory inspection may be revealed to be rough and irregular when seen through a bore scope. Greenleaf's report (Rifle No. 146) details how pressure increased as the number of rounds fired through a test barrel grew larger. This can only be attributable to a deterioration of the throat and leade on that particular barrel. In this instance SAAMI standard barrels were used and showed no irregularities, and it was only when the same ammunition was fired in a 'field' barrel with more generous tolerances and wear in these areas that problems were seen.

Bullet hardness and stiffness: The shape and construction of the specific bullet used can be a major factor in the levels of pressure developed by any given load. Bullets undergo some degree of deformation as they enter the bore, and the force required for them to engrave the rifling and obturate to bore dimensions can vary considerably.

Temperature: We know that pressures tend to increase as the barrel heats up, and a round that produces perfectly normal pressures from a cold barrel might show signs of excess pressure when the barrel is hot.

Work presented here answers questions. Some of the findings support theories offered to explain S.E.E. some don't. We haven't, for example, seen any evidence to indicate that there is ever an explosion, and many authorities doubt that there is. Perhaps what we need is a better name. Taken to its most basic component, what we have is that most fundamental cause of catastrophic failures: a bore obstruction. The difference here is that the offender is the bullet itself effect rather than some external source is both predictable and reproducible in the light of this new evidence, but it is highly dependent upon a combination of factors that produce disastrous results. If one or more is absent, everything will probably turn out fine; but when all come together, pressures rise and, sooner or later, sooner or later, something will fail. While it would appear that slow-burning powders contribute significantly, until now we didn't exactly know what to look for. I think it's at least theoretically possible for a bullet to stop in a barrel if the other conditions are bad enough with propellants other than the slower grades.

Have you ever fired a load that you had used often and suddenly gotten signs of excess pressure such as difficult bolt lift or flattened primers, and then fired another that seemed perfectly normal? I think this happens with some frequency, and our normal recourse is to shrug our shoulders and also be a bright red flag waving in keep on shooting; h6wever, this could front of our nose that is telling us that something is wrong. In the light of these findings, it could be telling us that a bullet did a stutter step before it went on out the barrel. The question then becomes what should we do about it. My first suggestion would be a careful investigation of the condition of the bore, especially the throat or leade to see if there is any erosion or roughness followed by thorough cleaning. A chamber cast might be in order to get precise measurements. If the barrel shows obvious signs of wear or throat erosion, the cure is obviously to replace it or set it back and rechamber. If the barrel appears to be within specifications, however, a change of bullet or propellant may be enough to solve the problem. The importance of this information is that it explains, with laboratory documentation, what can happen when the wheels fall off in the worst way. It seems like such a reasonable answer to many of the mysterious ka-booms that good reloaders have had with good handloads, and it is something we all need to keep in the back of our minds in case we encounter something out of the ordinary. While the data here was generated using the 6.5x55 Swedish cartridge, the observations are not specific to that round. They could occur with almost anything.

[felix]

Bad assumption, Larry, in that article. This condition they encountered has nothing to do with the throat dimensions as they stated in black in white. Short throats, new barrel having no more than say 200 condom rounds through it, exhibited the same scenaro. 25 grains of H322 (the first lot issued to public) in a 308W with powder down on top of a fully engraved 180 grainer with WW primers of the day did the very same thing OUT OF A PERFECTLY CLEANED BARREL. Three shots were taken, each with a DIFFERENT characteristic in RANDOM sequence as to "pressure" before I pulled the remaining rounds checking for powder amount variation. Nada. ... felix

[StarMetal]

Larry,

Good report, but until the labs can set all the the variables to have a consistant blow-up with each and every shot gauranteed, I don't buy it. I've also had more they quite a few rounds that either didn't have powder in them or the powder wasn't ignited by the primer...that didn't even push the bullet out of the case. I've never in my life time had a bullet pushed several inches up a bore by a primer alone. The one case where the primer lit off but the powder didn't was with a 243, I believe the powder was some bulk 4350 that I suspected wasn't stored in air tight moisture resistant containers. At any rate I waited a good while before ejecting the round and when I got home I pulled the bullet. The powder had all the graphite burned off of it and it was yellow, the color before it's graphited and the primer was spend. Never moved the bullet a smidgen. Now I'm NOT saying a primer doesn't push a bullet out of the case...I have had it happen, but I've also have had where it wasn't pushed out of the case on quite a few different rounds including both rifle and pistol. What we need is a thorough test on primers pushing bullets.

I think there are too many variables and I think they may be closer to what is happening, but in my book no cigar.

Joe

[felix]

Joe, there was a test on the primers pushing a condom out of a barrel. Done in 1996, I think. Check out your past Precision Shooting magazines in and around that time. Something like 20 primers tested. Yes, in the gun(s) they used, the condoms made it up into the barrel quite a ways. Keep in mind the gun was a tight necked piece. ... felix

[StarMetal]

Felix,

Yes, I don't doubt one bit what they found. Apparently there must be a wide range of variables with using our personal firearms. How tight the chamber and neck is, how tight the neck tension on the bullet, the bullet diameter, the crimp..type of primer, etc. , go name just a few. If we all performed this test and home and reported here I bet we would get tests that showed the bullets didn't leave the case to bullets went up the bore pretty far and everything inbetween.

Yes we agree on this one Felix.

Joe

[StarMetal]

I'll have to agree with Felix on the throats. There are way too many shooters, like varmint shooter and 1000 yard target shooters that definately have their rifle chamber throats change sizes in a very short time period that keep on shooting the same load until the accuracy deteriorates to the point where they scrape the barrel . Don't hear too much about blow-ups from them.

Joe

[BruceB]

Howdy, all;

Well, I HAVE had a case (no pun) where the bullet stopped about four inches ahead of the chamber in a 7mm Remington Magnum. When I say "stopped", I mean, that was where I found it while examining the wreckage of a Browning Safari-Grade FN Mauser. No primer is ever going to push a bullet that far, especially a heavy-for-caliber, thick-jacketed Bitterroot.

There was also visible evidence of a low-pressure condition following ignition, this being a LARGE shoulder collapse extending over half the length of the case. The collapsed area evidently survived due to the later extreme pressure being on both the inside and outside of the case wall. The entire head of the case was vaporized, with brass plating in evidence all through the action.

The action was ruined, but held together (as designed) with the third lug bearing HARD in its recess and the main lugs imprinted into the receiver almost 1/8 of an inch. Many parts were either distorted by the gas or simply missing.

Another article by Roger Stowers in a Handloader issue in the '80s described his REPEATABLE creation of the SEE phenomenon in a big-case 6.5mm wildcat, as I recall.

Many thanks to Larry for his posting of this fascinating article.

[Larry Gibson]

Felix/StarMetal

First my response was to demonstrate that S.E.E. had been reproduced in laboritories and was no longer theory. No one says S.E.E. is "an every shot" phenominon and therefor should be duplicated every shot. The fact is it has been duplicated.

Like BuceB and others I too have had bullets stop up the bore. I have also been present when three S.E.E.s occured. A 6.5x55, 280 Remington and a .308 Win. H4831 was used in the 6.5 and .308 and Mrp was being used in the .280. The circumstances were very simular to the description in the article, actually almost identical. I also have had bullets moved out of the case and stuck in the throat (cast and jacketed) by the primer alone. It depends on case volume and neck tension. The article simply states that with reduced loads of slow powders the bullet can be pushed forward into the throat and stick there prior to proper ignition of the powder charge. This in essance is an obstructed bore. I was not able to print the oscill -whatever that machine is - graphs which clearly show the delayed pressure curve and the pressure spikes when the bullet sticks.

I also noted that neither of you mentioned your guns blowing up when giving the reasons you think S.E.E doesn't happen that way. Can't say as since you didn't have an S.E.E. that your disagreement is valid. Your just pointing out anomalies. Note that in most every case of S.E.E. that involves slow powders it is not the first shot that explodes but is one of the subsequant rounds. Something causes the bullets to stick. Felix is perhaps fortunate that he quite shooting after three rounds as it looks like he was on the verge of an S.E.E. It also doesn't have to be jacketed bullets either. There was a couple of interesting S.E.E.s reported a couple years back involving Contenders with 45-70 barrels, 300 or so gr GC'd hard cast bullets and light loads of 2400. Handguns were being carried with muzzle down and were simply raised to fire. First shot was click - bang, second shot was click - boom. Same principle, simply an S.E.E.

Larry Gibson

[StarMetal]

Larry,

I wonder if a jacketed bullet was loaded up against the rifling and the powder charge adjusted accordingly, if SEE would disappear?? At least in high power jacketed rifle loads.

Joe

[StarMetal]

Larry,

How about the way you have told us you get a stuck bullet out of the bore, by firing a charge of powder in an empty shell, behind it. In essence a large capacity shell. Why isn't the bullet up the barrel an obstruction in this case? What's the difference if a bullet gets pushed out of the case and then the pressure poops out for a micro micro second then starts again in comparison to your bullet removel method?

The way I'm looking at this is like for fire. For fire you have to have oxygen, fuel, temperature for it to burn. Of course a source of ignition too. If anyone of those things are missing, there will be no fire, even if the remaining ones are drastically changed. That's how I look at SEE. If they know what causes it 100 percent they can duplicate it 100 percent. Until then they will never convince me.

Joe

[rockrat]

Had a SEE happen to me with a near new S&W M29 sihlouette. Just bought some AA#9 and was trying it with a 295gr SWC. I had pan weighed each charge and dumped in the cases in the loading block. Visually checked each charge as to height in the case. Took out the next day shooting at a target and the last 9 rounds at a few P. dogs. On the 7th round, there was a weird sound , no recoil, and a kinda pink flash. Wondered where the P.d. was as I didn't see the bullet impact(had previous shots) and the topstrap was in my line of sight(almost 90 degree angle) with part of the sight in my shirt and my friend 50yds away wondering what that was that flew over his head (part of cylinder)! One SEE is enough!!!

[StarMetal]

rockrat,

How do you explain what happen? If you're positive that all the charges were perfect, how you explain it. It's not SEE, it's something else then. I haven't looked your load up to see if it was max or pass, but will guess it wasn't.

Joe

[versifier]

Larry,
Thank you for the posting. A most informative article and enough food for thought to keep me chewing on it for a while. We have had some good discussions here about SEEs and their possible causes. I am still in the camp that thinks eventually we will find several different causes, possibly even differing causes for different action types. Every bit of good research fits another piece in the puzzle.

As to powder bridging with extruded propellants, I have a simple technique that I use with my Uniflow, and it will work with any steel drum type measure. I tap hard twice on the filling stroke, then tap hard three times on the dispensing stroke. It yields measurably more consistant charges, and it minimizes the bridging phenomenon. You can see its effectiveness through the transparent plastic of the drop tube, and the measure does bridge with only one and sometimes with only two taps when measuring IMR powders. It has become a learned reflex after years of doing it, and I do it automatically even with Alliant and othe easy to meter powders.
I use loading blocks and visually check each case every time, and I can honestly say that in more than thirty years and god alone knows how many thousands and thousands of rounds, I have never had powder bridging cause a partially/overcharged case. I have, when interrupted during the case charging operation, both missed a case and restarted on the wrong one and double charged, but visual inspection with a bright lamp has always caught the empties, and the overflow has clued me in to the doubles. I am very paranoid when using pistol powders in handgun and rifle cases in charge weights that fill less than half the case volume, and I usually check them twice with the bright lamp. I am a creature of habit, and I rely on my habitual routines help to keep me safe.

[Larry Gibson]

Larry,

I wonder if a jacketed bullet was loaded up against the rifling and the powder charge adjusted accordingly, if SEE would disappear?? At least in high power jacketed rifle loads.

Joe

That may or may not work, don't know. However we need to remember that SEEs are generally caused from a combination of conditions; reduce charges of relatively slow burning powders (leaving some air space), a relatively long throat, a roughened or fouled throat and the probable positioning of the powder at the front of the chamber.

"How about the way you have told us you get a stuck bullet out of the bore, by firing a charge of powder in an empty shell, behind it. In essence a large capacity shell."

The equation there utilizes a small charge of fast burning powder (Unique to be specific) which ignites and burns efficiently in small doses in large cases. The fast powders also don't have the deterrants on them to control burning rates like the slow powders. I also advise (as does Hatcher who I got this method from) that the muzzle was raised prior to firing to position the powder back against the primer. The use of easily igniteable fast burning powders in large capacity cases for reduced loads have not resulted in SEEs. Double and triple charges of the fast powders in large capacity cases have resulted in exploded firearms but these were primary explosions not secondary ones. The faster powders have a proven track record with reduced charges as do most of the medium burning powders. It is the slow burning powders that get into SEE situations. A single charge of 10 gr of Unique does not generate anywhere near the max pressures in an '06 regardless of how it is ignites. It is a safe, proven method of removing a stuck bullet. I would not suggest it be done with a 90% case full of 4831 though.

I am not suprised that rockrat had an SEE with AA#9. It is a slower burning pistol powder that sometimes has ignition problems. I also had similar (didn't blow the gun but I had bullets stuck in the forcing cone) problems with it and H110 when standard primers were used and the cases weren't full. That was a long time ago before I realized what SEE was about. Note all the warnings these days about using reduced charges with such powders and the recommendation for magnum primer use. I do use both powders but they are top end loads with plenty of neck tension, a strong crimp and magnum primers. No problems then.

Let me ask this; Are you and Felix saying there have been SEE problems with cases full of the slow powders and cast bullets? Reason I ask is I've not heard of it before and I've shot quite a few such loads the last few years with powders such as 4831, RL19, RL22 and H414. These were shot in the .308 and the '06 based on input from this forum as I was trying to search for the holy grail of high velocity cast bullet accuracy; sub 2 MOA accuracy above 145,000 RPM. I've not had any indication of SEE with such loads. Has anyone?

Larry Gibson

[StarMetal]

Larry,

No, I'm not saying I've seen SEE with cast bullets. Felix may have though, he's been in this shooting business for a long time.

You the firing of a cartridge takes place in micro seconds. I wonder in the event of a SEE, if because things don't go quite right lighting the powder off, that it adds alittle time to the whole sequence that the pressure created in hell inside the barrel longer and that causes the problem? You know , pull the trigger FLASH, powder burns, BOOM bullet gone. But in a SEE maybe it's pull the trigger FLASH and powder goes fizzzzzzzz burn BOOM BOOM gun is ruined. Just a thought.

Joe

[waksupi]

Interesting. Has anyone else ever heard of SEE occurring in a revolver? I wouldn't think it possible, with the cylinder gap for the pressure to escape through.
hmmmmm.........

[rockrat]

StarMetal. All I know is that I later found out that the load I used was waayy below what should have been a starting load. The first cylinderful was quite accurate and had planned on using it in a sihlouette match the next day. Probably taken a chunk of my leg instead. :violin:

http://i34.photobucket.com/albums/d149/Bigdog337/DSC00044.jpg




See if this works!!!

[Larry Gibson]

StarMetal

" But in a SEE maybe it's pull the trigger FLASH and powder goes fizzzzzzzz burn BOOM BOOM gun is ruined."

That seems to be the case, while the "fizzzzzzzz" is going on the bullet moves into the throat or bore and becomes stuck. Then when the "burn" happens the SEE occurs.

Waksupi

Rockrat's picture/example is one. It has all the classic elements; reduced load of slow burning powder, long throat (cylinder throat to forcing cone and fired successfully several times before SEE.

I've seen several of those and like I said earlier am lucky I didn't have one. Back in the late '60s and early '70s there were several revolvers (most PPC competition revolvers in .38 Special) blown in a similar manner. Many believed initially that the low volume charge of 2.7 gr Bullseye under the WCs was "detonating. After exhaustive research by Hercules it was determined that it was not detonation but a matter of double and tripple charges that were occuring with the use of the C&H (I think that was the name) progressive reloading press. The press went defunct, 2.7 gr Bullseye is still an excellent target load and there've been no more blow ups. They were over loads though and not SEEs. However, SEEs such as rockrat's still occur with some frequency.

Larry Gibson

[felix]

I have NEVER seen, or even heard about, a SEE with a full case of powder. However, I know of a person killed by standing behind a gun with bolt out, but by a cartridge case as a projectile when the round was tapped by using a hard ramrod. Vibration was enough to set off the powder and the case blew out the back, bullet remaining with ramrod intact. H322, early version. The same powder I had when I had a SEE, three times in a row. Couldn't believe it then, but after seeing other complications with that same lot of powder, I became an advocate rapidly, even though the term SEE has been dreampt up considerably later. ... felix

[felix]

Because of this occurance (last post) I have concluded without any doubt that WAVE action is the culprit. Sending a boolit down the bore, and then having the powder catch fire will shove the boolit out sorta normally provided the boolit does not expand enough causing a "tight neck" simulation in the bore. If the boolit expands too much, then the wave action will surely take place, and possibly setting some, and sometimes all, the powder off at once. Those folks in the lab are not setting up these conditions for the criteria to happenstance, else they would conclude the same conclusions that I have. Keep in mind that the primer in the case that killed the person was still 100 percent intact. This indicates that heat or force did not affect the primer. The time was just too short. WAVE ACTION!!! ... felix

[StarMetal]

Felix,

Please explain how vibration set off the powder.

Joe

[felix]

Ok, Joe, I will try. All material things have a breaking point, called in math terms a set of eigenvalues where each represents a certain frequency. If you will, a barrel sweet point, for example, is the same condition but in a positive sense instead, PROVIDED the frequency
is not an eigenvalue. If a sweet frequency is EXACTLY equal to a sour frequency, sooner or later the barrel will crack. It will be sooner if the frequecy is high, and much, much later if the frequency is a low one. An example of a low frequency blowup is when a suspension bridge can be seen swaying in a consistent pattern with increasing amplitude because of a certain wind velocity (speed and direction. Same thing can happen when a bunch of folks cross a bridge with only a few anchoring points. A bridge is no longer designed without extensive eigenvalue computations with many different kinds in loads (wind, water, cars, etc.). An example of a high frequency blow up is when the spaceship (War of the Worlds) couldn't handle the sound waves generated by some loud speaker on a truck. Sharper the offending frequency, AND, sharper the hole is in the material to be blown up, the more percentage of power is garnished by the material from the offending source. This is why microwave ovens work better for some foods (material) and not others. The E=MC2 works here very nicely, which says that energy and material are the same but in different forms. We know that all material is composed of vibrating somethings, and adding external vibrations of the same frequency of the majority somethings will play havoc on that entire material. ... felix

[jhalcott]

star ,a friend of mine was shooting Sillywets with his DanWesson 44mag. he had fired 3 shots and the 4th "acted" funny.A click,then a large flash from the barrel cylinder gap.Since there was no indication of the bullet hitting down range,I made him check the bore.He had already cocked the hammer for his 5th shot.He reluctantly opened the cylinder and looked into the barrel.the bullet WAS in the bore.There was also lots of unburnt powder The last shot was longer than when he loaded it.It was made up in old brass that had become work hardened from 15+ shots. The bullets were cast from wheel weights and not gas checked. SEE or what??

[felix]

No, a SEE would generate such a force as to move the boolit out at some fantastic velocity, or just blow the gun up pronto. In your situation, I suspect the case fell apart from being too brittle, or the powder/primer was infected (age or what???) enough for the load to became a squib. Were the first three shots accurate? Drinking cokes during loading? Need some history here. ... felix

[Larry Gibson]

jhalcott

Felix is correct, there was no SEE. However, I'd say your friend was damn close to one. It appears fortunate that the bullet moved into the barrel and cleared the barrel/cylinder gap. This allowed the gas to vent and prevented it from reaching max pressure. Had the bullet stuck in the throat of the forcing cone and obturated to seal the throat of the cylinder the Dan Wessom my have ended up looking like the Smith & Wesson picutered above.

Larry Gibson