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Old November 17, 2012, 11:27 PM   #1
Swampstalker
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Fuller’s Earth, Secondary Explosive Effect, and How Time Flies

Howdy, Foax!

I’m reliving “those famous days of yesteryear,” when reloading was once for me a compelling, daily routine. After a hiatus of more than 40 years, I’m preparing to introduce my adult son to the hobby, to round out his appreciation of firearms science. In the course of my preparations, I discovered that I cannot seem to find any contemporary references to the once popular practice of “topping off” incompletely filled cartridge cases with Fuller’s Earth, ostensibly to prevent the phenomenon which we still know as “Secondary Explosive Effect.” If adding Fuller’s Earth to partially filled cases is truly no longer done, can anyone tell me why not? In other words, after I left off reloading in 1970 to help defeat the Evil Empire, what happened next?

Thanx & best regards, Walt
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Old November 17, 2012, 11:49 PM   #2
Jimro
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Because adding dirt to your cartridge is not good for the bore of your rifle.

The secondary explosive effect takes place with slow powders, IMR 4831 or N205, when used in low case fill loads.

This effect is not known to happen with faster powders such as IMR 4064 or H4895.

Choose an appropriate powder for the cartridge and bullet weight you are reloading, and all will be well. No need for a case filler.

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Old November 18, 2012, 10:29 AM   #3
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Walt, Adding anything on top of the powder charge changes the internal volume of the case and will increase pressure for any given powder charge. In normal, center fire cases using smokeless powder, with a powder that is appropriate to the cartridge, no filler is needed, and may in fact reduce accuracy.

Black Powder cartridges are a different kettle of fish...in any event, consult a good manual... one updated in the last ten years or so, and choose a good powder...Lyman's manuals have always indicated the best powders for velocity and/or accuracy as a part of their write up....I'd suggest starting there. Forget the fillers, they're just not used anymore.

And welcome back to the fold....Rod
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Old November 18, 2012, 11:03 AM   #4
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There are modern alternatives to what you're trying to do, probably. Tell us what your goal is and we'll help you get there.
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Old November 18, 2012, 11:59 AM   #5
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Modern high power rifle shells do not need fillers to work. At least not as long as the powder-fill is at least 85% to 100% and above, which is a compressed load. Most powder now a days is not position sensitive.

Older black powder cartridges like the 45/70 usually run at 50% powder-fill, then a filler can make a difference on the plus side for accuracy and better/closer extreme spreads.

Fillers used today are; Dacron used to give quilts their fluff, and kapok which is used in life preservers. Since both are fluffy and weigh very little for the volume they occupy, the don't raise pressures much, if at all.
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Old November 18, 2012, 12:49 PM   #6
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Don't know exactly what Fuller's Earth is, but today Cream of Wheat, and Dacron fluff are used as fillers (I'm sure there are other fillers used, I'm just not familiar with them). The use of fillers isn't real popular today as powder density/loads usually can reach the 100% case capacity safely without anything to take up air space in the cartridge...
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Old November 18, 2012, 01:35 PM   #7
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There was pre-ignition, there was two flame fronts colliding, there was knock, anti knock? All having to do with Ethel (http://www.thefreedictionary.com/tetraethyllead) in the gas tank, then there was timing and the ability of the ethyl in the gas tank to prevent knock. Then came auto mechanics, auto mechanics applied the theory/principles of combustion in the chamber to combustion? in the chamber, and, to them it made sense (to them).

(Then someone wrote and recorded a song about having Ethel in his gas tank and no girl in his heart)

There was a phenomena that involved chance, meaning it will not happen every time but, there is a slight/remote chance bad habits will result in the next round fired will render your fire arm scrap, the auto mechanics did not buy into a foreigner getting into their business/theories/principals. The foreign company went on about their business, they claimed time was a factor.

Powder ignition can be position sensitive, I am not the fan of spreading my powder thinly across the bottom of the case when laid on its side (as in from the bottom of the case to the base of the bullet). When the trigger is pulled there are two speeds to consider, the ignition of the primer and the burn speed of the powder, I know, ‘it’ is fast, but, I have been at the range when a shooter/reloader was in mortal combat with his pistol, he could not pull the trigger, he could not open the cylinder, he could not get the cylinder to rotate. In short his Model 66 was locked up, he had a bullet stuck between the cylinder and barrel. One of his newly reloaded rounds had no powder, the primer launched the bullet.

then there is the two speeds to consider, the primer and the powder burn speed, the primer is the fastest , the powder comes in second, then there is the powder position, if the primer can launch the bullet into the forcing cone the bullet can have a running start but because time is a factor the bullet can stop in the forcing cone at the rifling, then comes the powder burn with an increase in pressure, everything is working, not as planned but working, when, suddenly and without warning the expanding gas caused by the burning powder has no place to go, the bullet is jammed, without time to get it moving again, the rise is pressure exceeds the ability of the fire arm to handle the pressure, as a results, the fire arm is rendered scrap.

Excuses: “I ‘musta’ had a double charged case....etc.. or “It handled like a doll buggy right up to ‘pulling the trigger’, like the Deacons Masterpiece there it lay all in a heap” or “All I have ever feed it is reduced loads, nothing but a steady diet of reduced loads”. Back to the phenomena, “It does not happen ever time, it can happen”, the foreign company moved on doing what they do and reloaders still return from the range with firearms rendered scarp without a clue. Reloaders apply a strange standard to the phenomena, if reduced loads cause the problem it should do it every time as in a repeatable results.

Then there is the DUH factor in reloading. “WHAT HAPPENED?” “I DON”T KNOW, I MUSTA HAD A DOUBLE POWDER CHARGE!!” Go through response that involving case weight and measuring, the most irresponsible answer has to do with accuracy. The last chance a reloader has to prevent an accident that could prevent rendering their firearm scrap is before firing, back to weighing components, if a reloader does not know the cases weight before loading there is no way to determine if a case has too much or not enough powder.

I loaded 250 rounds of 30/06 on my Dillon 550B, after I finished I weighed ever round, there was 18 grains difference between the heaviest and lightest, not a DUH moment, there was that much difference between case weights.

Back to the range with the shooter with the Model 66 S&W, we drove his bullet back into the cylinder, in his mind everything was good to go, so he started to chamber 6 more reloads, and we had issues with that, he did not know if one of his cases got no powder and the next case got twice the recommended daily dosage, he did not weigh his cases before and again after, we could not convince him a scale, bean or digital, could distinguish the difference in weight between a round with powder and a round without powder, we offered him all the ammo he could fire, we offered to help him with his reloading, we offered to give or loan him equipment to go with his brand new Dillon 550 B. He packed up all his equipment and left.

Then there is the BIG TRAIN WRECK, an event staged between two trains, bleachers were set-up, spectators were knocked off the bleachers, backwards, the train wreck had nothing to do with reloading, but there is another phenomena, pack a case with powder then pack the case with a filler, pull the trigger, between the expanding gas and the filler is a collision, it is possible to ring the inside of the case when the filler expands and or is compressed, I am not a fan of reduced loads, when I form cases I form first then fire, when I eject a fired case it is ejected as a once fired case, others fire form.

F, Guffey
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Old November 18, 2012, 03:15 PM   #8
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F guff, how did that rambling diatribe have anything to do with the OP's question? Auto mechanics? I thought this was a reloading forum?!

Fillers have been used with great success in cartridges for eons. In the case of a square of dacron pushed down on top of the powder, it holds the powder there by friction of the square of fabric on the sides of the case. It's very light weight does not affect chamber pressure. OR ring a chamber. A solid wad would do that, IF it happened to come loose from the bullet to position itself between the powder and bullet.
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Old November 18, 2012, 03:40 PM   #9
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Welcome back and thanks for asking our advice

Quote:
Swampstalker

Fuller’s Earth, Secondary Explosive Effect, and How Time Flies

(edited for brevity)
In other words, after I left off reloading in 1970 to help defeat the Evil Empire, what happened next?

Thanx & best regards, Walt
Really, few radical changes have occurred in the science and art of reloading since the development of smokeless powder. There have been (as you see) incremental changes. Abandoning the use of fillers is one. Snuffy and mikld pointed out that the wide choices of new powders allow picking ones that don't require fillers (because of near 100% case fill, position insensitivity or stable burn rates over a wider range of pressures).

What chamberings will you and your Son be loading? Are you dusting off your old press or getting new gear? What are your goals?

Lost Sheep
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Old November 19, 2012, 03:44 PM   #10
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“F guff, how did that rambling diatribe have anything to do with the OP's question? Auto mechanics? I thought this was a reloading forum?!”

Snuffy, some of by best friends are/were auto mechanics, but when it comes to rendering a rifle/pistol scrap I do not believe the detonation rational and that part where they tell me “What you do not understand is there is are two flame fronts and they meet in the middle etc., etc..”

the case forms a column for the powder between the case head and bullet base, I am the fan of igniting my powder column from the head of the case to the base of the bullet, I do not want anything between the case head and bullet base but powder, but if I do put something else (besides air) between the top of the powder column and bullet base the something else is going to compress, if the material that is placed between the top of the powder column and bullet base is abrasive a ring can appear. I know, some pack toilet paper in the case to keep the powder stacked against the primer, I am out of John Wayne toilet paper, even with John Wayne toilet Paper, when compressed with thousands of pounds of psi, toilet paper is abrasive.

I am not the fan of reduced loads, I believe powders are position sensitive, some more than other.

F. Guffey
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Old November 19, 2012, 05:16 PM   #11
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Fuller's Earth?
What ever happened to using toilet paper?
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Old November 19, 2012, 05:36 PM   #12
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I believe that Mr. F. Guffey is trying to insinuate (albeit in a rambling and disjointed way) that using fillers in general will cause chamber ringing. In other words, I think he is trying warn people away from fillers. (Why he couldn't just SAY that is beyond me.)

So, I will say just what I always say to those who trot out that old swayback nag.....that fillers will likely ring your chamber and ruin your gun. What I say to that is - NONSENSE. Fillers will cause problems if the user does NOT know HOW to use them.....and uses them incorrectly. So, if you don't know how, then DON'T do it. Simple as that. Leave fillers to those who KNOW - or take the time to LEARN - rather than trying to throw a wet blanket over the concept.

I myself (and others here) have been using fillers for many years (over 10 years, in my case)....with NO ill effects whatsoever. I have, in fact, achieved improved accuracy, with jacketed rifle bullets, moderate loads of medium-slow rifle powders (IMR 4895, for example) and dacron fibrefill. I use dacron or cotton wool filler in EVERY one of my paper-patched, cast bullet 8mm Mauser loads (and have for many years) - with excellent accuracy and consistency. With it, I get 2100 - 2200 fps from an 18" barrel, 1.5" or smaller groups at 100 yds, a clean bore after shooting 40 - 50 rounds and no discernible barrel wear - all while using soft, PLAIN base cast bullets (NO gas checks). NO rings in my barrels, either.

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Old November 20, 2012, 06:00 AM   #13
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It must be because I am old but I actually understood and enjoyed Frank Guffey's rambling explanation. We must have run with similar folks going thru life.

I will not get into the filler and fireforming arena-enough said already.

As always, I seem to pick up one little bit of interesting information here every day.

Gary
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Old November 20, 2012, 10:08 AM   #14
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Yes. I think the engine cylinder is apropos. Knocking is detonation of the gasoline and air mix. It used to be hypothesized that it was initiated by echoing waves in the cylinder forming additive nodes, but the advent of transparent cylinders and ultra high frame rate cameras showed that, more mundanely, it simply initiates at the hottest point in the cylinder. Well, we've known since the Civil War that nitroglycerin would detonate spontaneously when it got warm enough, so perhaps that shouldn't have been such a total surprise.

It seems likely to me that detonation in firearms is likewise initiated by heat once some portion of the powder gets hot enough to fuse but is delayed in receiving an ignition spark. Filling the case better helps gets it to light up before fusing. It also increases the capacity of the charge to absorb heat by phase change as fusing tries to start (enthalpy of fusion). You see that in squibbed out loads, where what looks like sintered chunks of powder of powder have formed, but are still porous as fusion is incomplete. More complete fusion would provide the contiguous medium a detonating compression wave likes to travel through, and may be what can happen to smaller charges.

I'll add a warning that, despite conventional wisdom to the contrary, SEE's can happen with fast powder, too. The Finnish Gunwriter's site describes a .308 disassembled by a load of 3 grains of N320 (pretty fast pistol powder; about 10% case fill in that example). Fast powder detonations are not as commonly reported as for small loads of slow powder, but when all the stars line up wrong. . . KB. Since reading about that particular event, I've made it a personal rule of thumb that even my loads of fast powders have to fill a case at least 20%.

I don't actually know if the reason for fast powder SEE's being less common is actually because of the powder properties or if it's just a self-selecting observation. The latter could happen due to these events requiring a lot of empty space in the case that you only get in rifle cartridge cases and because slow powders are more likely to be what a rifle handloader has on hand when temptation leads him to run experiments with greatly reduced loads.

Chamber ringing happens. It's was described one time in, I think, The Fouling Shot by a fellow who didn't believe in it until he got a bore scope. It can happen very slowly, and I think his was in a chamber with 10,000 rounds of filled case ammo through it that he found the forming. He just hadn't been aware it was there before looking through the scope. That said, I've never heard of the light plastic fillers causing a problem. Polyester (e.g., Dacron) pillow stuffing, for example, or the commercial Puff-lon filler. These seem to melt down to very little volume, so its as if, once ignition gets under way, they get out of the way.

Rapid chamber ringing seems to me more likely to happen to fellows who develop a load without filler, then add filler without reducing the charge weight, not realizing that robbing the chamber of empty air space will greatly increase his peak pressure for that same charge. The air-filled pillow stuffing doesn't take away nearly so much total air space, and that may be another reason you don't hear about ringing with it. It allows for larger charges.
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Old November 20, 2012, 10:45 AM   #15
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Can someone show this rookie what chamber ringing looks like? Maybe a bore scope picture or a drawing of some sort? Curiosity is killing this cat.
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Old November 20, 2012, 12:00 PM   #16
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Mainly because SEE is bogus.
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Old November 20, 2012, 12:19 PM   #17
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Quote:
Mainly because SEE is bogus.
I won't go that far...Yet...

But it is my understanding that many people and companies with expensive test equipment have yet to reproduces the 'effect'...Not once...

Anyone with evidence to the contrary, I'd really be obliged to you for showing it to me...
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Old November 20, 2012, 01:51 PM   #18
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It's not bogus but it is a bit mysterious.

Many people thought the secondary pressure spike near the muzzle that can be created under certain conditions was nonsense too... until one man figured out how to reproduce it, and blow the end off rifle barrels.

I suspect that SEE with really low charges is a similar phenomenon. The bullet begins to accelerate but pressure drops rapidly and the bullet's acceleration (not necessarily speed) drops off. The shockwave catches up and a localized ultra-high pressure event is triggered, which propagates through the remaining powder and "BOOM!" It just happens very close to the chamber instead of at the far end of the barrel.

I have no evidence to back it up, but it makes sense in my little brain.
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Old November 20, 2012, 02:37 PM   #19
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Thanks for the article...

From the link:

Quote:
If there is insufficient gas produced by the powder (burn rate too slow), pressure behind the bullet will drop excessively. Then, as the bullet's rate of acceleration falls due to bore friction, gases may "catch up" to the bullet before it exits the barrel and produce a secondary pressure event. In the above load we believe the heat generated from initial ignition coupled with a secondary pressure event increased the burn rate of residual ball powder to near detonation.
If I understand this, they are theorizing that the bullet is not under constant pressure past the initial spike, and that due to the 'slowing of acceleration' the expanding gasses then 'catch up' to the bullet?

Not proof of SEE, but interesting theory...
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Old November 20, 2012, 02:40 PM   #20
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I suspect that SEE with really low charges is a similar phenomenon. The bullet begins to accelerate but pressure drops rapidly and the bullet's acceleration (not necessarily speed) drops off. The shockwave catches up and a localized ultra-high pressure event is triggered, which propagates through the remaining powder and "BOOM!" It just happens very close to the chamber instead of at the far end of the barrel.

As I pointed out earlier...If this is real, then you'd think this amazing equipment and software would be seeing anomalous/extreme events at the chamber, even if they do not end in catastrophic failure...
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Old November 20, 2012, 02:50 PM   #21
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An alternate explanation is that the primer explosion pushes the bullet into the lands, jamming it in place. This causes the burning powder to not have the normal expansion space because the bullet is not moving forward and the force of resistance is greater on a stationary object than a moving object.

This causes a "plugged bore" event and the pressure level in the cartridge increases to detonation levels, and then boom.

The exact causes of SEE aren't as important as ensuring the conditions that are known to cause it are avoided.

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Old November 20, 2012, 02:57 PM   #22
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Quote:
Originally Posted by Salmoneye
As I pointed out earlier...If this is real, then you'd think this amazing equipment and software would be seeing anomalous/extreme events at the chamber, even if they do not end in catastrophic failure...
You'd think, but the phenomenon certainly does happen. I suspect that the exact chain needed to cause it is very particular. Like getting bit by a shark while surfing, hit by lightning on the beach, having your ambulance crash and then your medivac helicopter crash after you're rescued from the ambulance. Unlikely to happen but given enough chances...

Quote:
Originally Posted by Jimro
An alternate explanation is that the primer explosion pushes the bullet into the lands, jamming it in place. This causes the burning powder to not have the normal expansion space because the bullet is not moving forward and the force of resistance is greater on a stationary object than a moving object.
I can't discount the idea entirely but we know how much extra pressure is created by jamming the bullet in the rifling and it shouldn't be any where near enough to create a bomb out of what should be a very low pressure system.

It seems unlikely to me but the whole thing is unlikely, so who knows.

It's possible that your idea fits with my idea actually. The bullet jumps forward into the rifling and then stops, rather than my initial suggestions that it just slows down. Could be that it doesn't stop entirely but the rifling slows it down enough... Any guess is as good as mine, I imagine.
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Old November 20, 2012, 03:11 PM   #23
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Alternate theory #2,

The increased surface area of a low case fill charge causes more powder to burn at once, increasing pressure faster than one would expect for a slow powder, until detonation heat/pressure is achieved. Filling a 300 Win Mag case to 50% fill would expose a lot more powder to the initial flame than a 90% case fill. If the primer flame ignited all the powder at the top of the stack causing the powder to burn downward this makes a lot of sense.

Normally the primer flame is contained towards the rear of the case by packed powder, and the powder burns from back to front (unless you modify your cases for frontal ignition).

Anyways, the SEE is real and there are lot of ways it could happen, at least in terms of physics/chemistry.

The problem with being a scientist is figuring out exactly what is happening. The problem with being an engineer is figuring out how to keep it from happening.

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Old November 20, 2012, 03:42 PM   #24
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I've heard that theory too, it's why it's typically recommended to not use loads of slow powders less than around 65%.

The trouble with detecting early warning signs and or pressure events that don't cause complete failures, I think, is the time scale of these events.

A "normal" pressure rise is in the neighborhood of .00025 seconds. A pressure event that burns all that powder fast enough to create the pressure which would be needed to blow up a gun, pressures that are 2x normal max and something like 4 or 5x the indicated pressure of these loads, might take like .00005 seconds or something.

Maybe detectable with the right equipment but probably not in the $400 price range of RSI Pressure Trace and similar consumer level equipment.
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Old November 20, 2012, 04:58 PM   #25
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Quote:
An alternate explanation is that the primer explosion pushes the bullet into the lands, jamming it in place. This causes the burning powder to not have the normal expansion space because the bullet is not moving forward and the force of resistance is greater on a stationary object than a moving object
Ed Matunas said this was the reason "Winchester will never build another .220 Swift rifle." The roughening of the throat by erosion from hot loads made it subject to this sort of stop and go pressure surge.
I am not sold on the concept but it is as good as any of the other wild theories that explain but do not predict.
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