Reducing loads below minimum?

[Ohio Rusty]

I've been doing some powder research for my next reloads, and I'm excited at the prospect of using Trail Boss. TB is recommended for cast boolits and low velocity loads, both of which I'm trying to achieve for C.A.S. when the wife and I get into the sport later this year (have to buy some guns to shoot!) My new LEE mould arrived yesterday, a 358-125-RF. A nice light bullet with a flat face, good for most target work. Hodgdon says in their load data for a 125 bullet 3.0 gr. of TB will give a velocity of 753 at 11.600 psi. I'd like to shoot this 125 bullet closer to wad cutter velocity of around 650 fps. When you start reducing loads by 10% or 15%, do you just get lower velocities, or do other factors come into play that I'm not seeing? I do know that if you get too small of a load, that detonation can occur. This doesn't seem likely being Trail Boss is so bulky and fills the case. Any opinions on reduced loads of Trail Boss? Testing will be done using a Ruger New Model Blackhawk with a 4 5/8's length barrel.
Ohio Rusty

[jerrold]

You said it yourself. Detonation is possible with too little powder. Don't guess it won' t happen. Don't take the chance. don't do it:coffee:

[felix]

You should have no problems with TB while lowering the charge, especially when the case is more than 50 percent full with the boolit seated. The primary reason is based upon its ignition characteristics more than anything else. When you see info in the reloading books where the average pressure of the loads used in the books is below 20K cup/psi, that would indicate the powder was made easier to ignite. ... felix

[tomf52]

Everything I have read about this detonation thing seems to be with the slower burning powders. There is much discussuion lately on many forums about shooters using 2 or 3 grains of Bullseye (a fast powder) in large bottleneck rifle cartridges to make soft plinker loads. If there was to be a detonation problem because of charge weight to capacity ratio you think it would show itself here. I have reduced Bullseye in 357 cases down to a very low level with no trouble. To repeat myself, the problem seems to be with the slower burning powders. Get some good books on reloading and read to enlighten and assure yourself before venturing too far from the norm. Lee's reloading manual has at least a small section on this topic. Hope this helps you, Tom

[felix]

A SEE condition can happen anytime when wave mechanics is involved. A primer is an explosive device, and sends out a strong shock wave. Should that shock wave bounce around and become additive in some crazy fashion as to ignite the powder all at once, or at least "major" portion of that powder, then you can expect that powder to become an explosive device as well, causing even more shock waves. There is probably not enough energy in 2 grains of BE to totally corrupt a gun, but any tight bolt lift from any light charge is indicative that a SEE condition was the cause. ... felix

Using a chrono is the only way to check out a particular load for real. Short of using a chrono, you can test loads for ES (extreme velocity spread) over a body of water. Any large deviation between shots is the most reliable indication that a problem exists with the load being used. ... felix

[Larry Gibson]

Sometimes it is not good to go below the recommended charge for powders for several reasons. Many powders do not burning efficiently until a certain pressure is reached. Going below that can result in bullets stuck in bores, lots of unburned powder to foul or jam things, the powder not burning and the bullet sticking in the forcing cone jaming the cylinder, etc.

The Bullseye detonation theory was disproven by Hercules and Fedeal Cartridge in extensive laboratory tests back in the late '70s. The myth continues.

SEE (Secondary Explosion Effect) is caused when reduced loads of slow burning powder are used. It actually creates the condition of a bore obstruction and has nothing to do with "wave bounce" or the shock wave theory. SEE is produceable in the laboratory quite readily. There was an excellent article published in Handloder Magazine's June-July, 1997 edition. Other similar articles have been published elsewhere. The "wave theory" and the "detonation theory" are still theories as ballisticians have not been able to replicate them.

Balisticians have replicated SEE and disproved "detonation" with Bullseye yet the myth continues.

I do not know if reducing loads for Trail Boss will work or not. I use Bullseye because it is ignition friendly and thus not very position sensitive. I have used as little as 1.3 gr of Bullseye in 8x57 cases with a 210 gr bullet (235 fps) for what is called "cat's sneeze" loads. In the 38 Special I have used as little as 1 gr of Bullseye with a 105 gr Lee SWC for gallery loads.

Bullseye is an excellent powder for the application of low end reduced/gallery/plinking loads with cast bullets.

Larry Gibson

[felix]

Larry, please define bore obstruction. ... felix

[Dale53]

Ohio Rusty;
A 125 gr cast bullet with a velocity of 750 fps in a full size revolver will already give you very light recoil. I cannot see the necessity of reducing recoil further. It WILL be somewhat more than a .22 rimfire but it should not AT ALL be a problem for even a slight built woman. Recoil recovery should not be a problem, either.

I have shot extensively where FAST double action work has been needed and I found no slow down using loads somewhat heavier than you are suggesting, here.

So, my suggestion is to simply try the Trail Boss loads as given by Hodgdon Powder (125 gr bullet at 750 fps). FWIW, many 148 gr target wadcutters have a velocity in a six inch barrel of 770 fps. They are TAME.

Dale53

[R. Dupraz]

Ohio Rusty:

Just contact Hodgdon. They'll know the right answer!

R. Dupraz
1st US Infantry
Fort Randall
Dept of Dakota

[Larry Gibson]

Larry, please define bore obstruction. ... felix

In the case of SEE (I believe I've posted that Handloader article here before) the primer explosion goes past the powder and pushes the bullet into the throat before the pressure curve of the powder ignition has the force to keep the bullet moving. The bullet sticks in the throat which is rough or fouled from one or several previous shots. The bullet is really stuck there and becomes the bore obstruction. The powder continues to burn and with no expansion down the bore the pressure rises to obstructive levels. If you've ever fired really light loads or pellets or wax bullets from primers only you know that there is an aweful lot of grit left in the throat areas. I have stuck two such bullets bullets in throats and they were really stuck. They could not be driven out nor shot out with another reduced charge. They were very stuck.

If you read through reports of SEEs you'll find most all SEEs occured on the 2nd to 10th shot. There may have been a hangfire in one or more of the previous shots, the chamber is either long throated or a light weight bullet is used (creates a long throat) and a reduced charge of slow burning powder is used. The 25-06 with 87 or 100 gr bullets and reduced charges of 4831 were notorious for SEEs. In the article it is the 6.5 Swede that is the offender. I've also seen a Swede SEE on one of our local ranges. He was using 100 gr bullets over very light loads of 4831 (surplus - he still had a keg of it). On the third shot the rifle blew. A most interesting SEE was the case of a fellow with a 14" Contender in 45-70. He had hunted with it quite a bit and had it throated to seat the Speer 400 gr bullet out to the bottom canalure. He was shooting some 300 gr HPs with a light charge of 2400. He fired three shots holding the muzzle down and raising it straight up level. Obviously the powder charge was staying in the front of the case. The third shot was a hangfire, a click - bang but he took no notice that something was amiss. The fourth shot was the SEE which destroyed the gun. A classic case of the bullet becoming the bore obstruction.

I know of no documented SEE with a cast bullet.

Larry Gibson

[Firebird]

It wasn't proved that SEE can't happen with Bullseye powder, it was calculated that 2.8 grains of Bullseye simply doesn't contain enough energy to blow a cylinder. This is in reference to the old bullseye shooting load of 148 grain HBWC in a 38 Special blowing cylinders during bullseye shoots back in the 50's. Hodgdon proved that it couldn't be because of detonation or SEE or anything besides double or triple loading the case since there simply isn't enough energy to blow the cylinder, even if the bullet is fixed in position, with only the standard load of 2.8 grains of Bullseye powder.

[felix]

You got it! ... felix

[Ricochet]

If you Google with various combinations of words including "pressure excursion," you'll turn up documents indicating that extremely wide pressure variations like 2X-3X are common with various reduced loads, but the peak pressures of the high rounds usually aren't high enough to wreck the gun. We all have tried loads that just wouldn't shoot, and this is likely a reason some of them wouldn't.

I've read and thought up various reasons why these effects occur, and likely several of them are valid under different circumstances. I've seen several statements from various folks (like Felix) claiming to be able to reproduce the phenomenon at will, without explanation of how. If indeed it's common knowledge among ballisticians, I'd like to read the details. Shouldn't be a secret if it's common knowledge among the ballistics pros, and sharing the knowledge with "the rest of us" could help to keep us out of trouble. I doubt there's any money to be made out of it, unless someone wants to turn expert witness for a plaintiff claiming that a loading data publisher knew a load was dangerous, published it anyway, and someone suffered damages. That'd be a hard one to make stick, I think.

I have a hard time believing that moving the bullet into the bore throat and sticking it could cause a destructive pressure rise all by itself. Jammed bullets certainly cause pressure increases, as QuickLoad's settings will confirm, but starting a jacketed bullet from rest against the lands still only requires a few hundred pounds of total force at most. That can only raise the shot start pressure by a few thousand PSI. If that situation's combined with the powder jamming into the bottleneck of a case in such a way that many of the powder grains shatter when it starts moving, or the mass of powder all "sloshes" forward and hits the front of the chamber with a "water hammer" effect, again shattering grains and exposing more surface area to burning, or the stuck bullet with a slow igniting powder contributes to a hangfire situation with gases heating the interior of the powder grains to burn much more rapidly when they do ignite, I could understand it. I'm skeptical of the bouncing shock wave theories, but can't show that they're wrong.

Anybody got a copy of that 1997 Handloading article I could read?

[felix]

Ricochet, use 25 grains 1970's H322 with actual 180 grain 311291, sized 308 for gun that normally shoots 311 just perfectly (as determined later), with quenched WW, in a close fitting throat belgium browning at a minus 40 degree angle, using 1970's WW standard large rifle primers. I still have gun, cases, primers and powder, and prolly some boolits left from that batch. I want JPL, MIT, CalTech to take it and do a number with it. PS.. Ambient was room temperature at about 40 percent humidity. ... felix

[Ricochet]

Interesting!

Is that what you shot three SEE conditions in a row with?

What sort of pressure signs did it produce? (Presumably not a kaboom.)

Now I'm wondering what it was about that load that produced the high pressure?

I agree, it would be fascinating for a well equipped lab to study such a condition and figure out just WHY it does what it does.

Thanks, Felix!

[Larry Gibson]

Anybody got a copy of that 1997 Handloading article I could read?

I've emailed you the article. I've read quite a bit regards to this subject over the years. It is difficult to extrapolate fact from opinion. I go with the facts when presented. A friend has an Oehler M42 that does measure pressure. He has found throughtesting that with the reduced cahrges of slow burning powders there are indeed pressure spikes that can be dangerous. He also found that with the faster powders the spike are from those charges hat burn efficiently vs those that don't. However as you state the spikes are still within safe parameters. Once the charge is in a pressure range where the powders burn eficiently the spikes are not present because all are in that range. He has tested numerous reduced loads with Bullseye and not found the spikes.

Larry Gibson

[Larry Gibson]

It wasn't proved that SEE can't happen with Bullseye powder, it was calculated that 2.8 grains of Bullseye simply doesn't contain enough energy to blow a cylinder. This is in reference to the old bullseye shooting load of 148 grain HBWC in a 38 Special blowing cylinders during bullseye shoots back in the 50's. Hodgdon proved that it couldn't be because of detonation or SEE or anything besides double or triple loading the case since there simply isn't enough energy to blow the cylinder, even if the bullet is fixed in position, with only the standard load of 2.8 grains of Bullseye powder.

I believe you are confusing the "detonation theory" with SEE. They are different. It was the charge of 2.7/2.8 gr Bullseye (the standard target load for HBWCs in .38 Specials) that was thought to detonate because of it's small volume in the case. In the case of SEE the powder does not detonate but burns normally.

Larry Gibson

[Larry Gibson]

Ricochet

It's coming in 3 messages due to length.

Larry Gibson

[felix]

Yes, Larry, the terminology is the problem, just like in the confusion of datum-line, headspace, et. al. As far as I am concerned, dataum-line/headspace are the same in context, as well as detonation/explosion/SEE. ... felix

[drinks]

[Larry;
Can you give me a date for when you posted the article?
I went to Handloader site, but they only have back issues available from '99.
Thanks, Don

QUOTE=Larry Gibson;160457]Ricochet

It's coming in 3 messages due to length.

Larry Gibson[/QUOTE]

[felix]

Wave mechanics is the only thing that excited a round to fire at a BR match. A bolt was closed upon a round that felt too tight. Freshly turned necks were not turned enough. The bolt was hammered open and knocked out leaving the round intact within the chamber. The round was hammered from the muzzle with a cleaning round, and the round fired at that time. The wife was holding the gun on the bags. The case flew out and killed the wife (died in hospital), and the case was extracted from her having the primer perfectly intact and unfired. The load was the typically loaded H322 6PPC round. Yes, upon investigation, that powder was the very same lot I had in my 308 load as spoken about earlier. WAVE MECHANICS supplied the energy necessary to ignite that powder, and that is not questionable. It does NOT take a genious to understand this, but apparently it does take an infinite amount of time for us who don't have confidence in our own abilities. Yes, unfortunately, "The myth continues" for most of us. ... felix

[Ricochet]

Larry, thanks for sending me the article! It'll be on my computer when i get home. :-D

[Uncle R.]

I've seen conflicting opinions and articles on Detonation/SEE/Wave Mechanics pretty much since I was old enough to read. I seriously doubt that anyone's figured it out for sure. I use the 2.7 grs. Bullseye load in my .38s with confidence but I'll tell you all that tiny loads of ANY powder rattling around in big rifle cases scare the crap oughta me... It only has to happen to you ONCE to make you a believer.
My first effort at a reduced cast load in a high-powered rifle was the RCBS 7mm 140 gr. Silhouette bullet in a .280 caliber Ruger 77V. The load was right out of the Lyman Cast Bullet Handbook of that era - perhaps 1980. The charge was Green Dot in an unremembered quantity but roughly 17 grs. Initial accuracy was HORRIBLE with groups maybe 2" wide and three FEET high at 100 yards. Obviously wild velocity swings - but younger and none too bright I kept at it, experimenting with (among other things) roll crimps and magnum primers in an attempt to get uniform ignition.
The last round of my final session with Green Dot left a tell-tale wisp of smoke from the breech and the bolt handle frozen tight. I tried forcing it - first at the range and then at home but couldn't budge it with any reasonable force. Afraid I'd break it, I took it to my friendly local smithy.
HE opened the bolt out of my presence (?) and showed me the empty case. The head was expanded so far that the case looked like a belted magnum. The primer (what was left of it) just fell out of the greatly expanded pocket as soon as the case was pulled from the bolt head. Obviously WAY high pressure - maybe 70 or 80K? God bless Bill Ruger and that model 77 - and out the door went ANY interest in loading shotgun powder in rifle cases.
Double charge? I suppose it MAY have been, although I was an experienced and careful loader even back then. But given that wild vertical stringing who can doubt that some weird delayed ignition/wave effect could have taken place? I can't speak for anyone else but I'll stay away from such loads in MY rifles...
Uncle R

[Nueces]

felix, can you recommend some reading on the wave mechanics hypothesis for this accident? Almost all reading I've done up to now in this area has been in the print media, very little experience on web boards, so I'm sure I've missed a lot of spirited analysis. I'd like to know how the investigator ruled out such things as ignition of a powder grain at the neck when the bullet was struck by the cleaning rod.

Thanks, Mark

[felix]

Mark, no, I cannot give you anything relating to this killing incident, except the article (very small, at that, as to hide it) in Precision Shooting. I can go and possibly find it should you ask for a reprint. However, it is not likely someone would use new cases without the gun being cleaned. BR guns are typically cleaned after every 8 to 10 rounds, and perhaps after as many as 20 rounds when using moly bullets, making the chance for some powder being ignited via friction quite extremely remote. Wave mechanics makes extensive use of math and by itself (as a beginner) would be mighty tough to comprehend. The areas of interest would be in the arena of eigenvalues. ... felix

[Nueces]

felix, thanks for getting back on this. It's hard to be clear about an idea on this sort of forum, without sounding like a pedantic PITA. So, sorry I didn't make my picture clear - was thinking of powder inside the case, perhaps at the juncture of bullet base and case neck. I know of an old case in which an early solid-fuel rocket technician was fatally injured when he torqued down the stem of a pressure bomb onto a flake of propellant - blew the stem through his head. That memory suggested the possibility of an ignition source for this other story. Anybody else ever clamp an old toy paper cap in a vise and tap the jaw to set it off? It will result in immediate attendance by the disciplinary-adult-in-charge!

I also appreciate your caution before wantonly exposing my tender gray cells to eigenvalues. However, please know that you may speak with complete freedom. It's not like you asked me to 'express my feelings' or anything really scary like that. :mrgreen: I'm actually equipped to talk hard science. Though I've been flying airplanes for a long time, one BA is in math and my PhD is in physics. I still enjoy figurin' stuff out and hearing how others do it. I'd very much like to try to wade through a wave mechanical argument in this case. Was this mentioned in the PS blurb? Your post just seems to indicate an established backstory for this idea, just lookin' for it, that's all.

Mark

[felix]

Mark, I'm glad you were not torqued off, like very well could have happened literally with that H322 like you said. Anyway you look at it, pressure was applied to transform the powder. You could have applied the same amount of pressure gently, and nothing would have happened except that the power would be just crushed. That means in the description of the powder in matrix form, describing the potential energy contained within, the matrix continuously displayed a non-zero characteristic equation during and after being crushed. Now, if during the crushing of the powder (mechanically, or by energy wave) the matrix went though a transition where the characteristic equation went through a complete zero pattern, the powder would blow. Getting into the transformation math would tax my feeble brain to the extent of keeping me up until this time next year. The last time I had to go through this stuff was bad enough. And, that was when I was in my 30's maximum (military contract). However, should you want to play, I will be your sounding board. So, fire away should you so desire. ... felix

[Nueces]

Hey, I do not want to mess with a man's rest! But, I do like to play. :-D

And, no wonder my Google work has not turned up anything yet - this is old military contract stuff. Plus, even years ago, when I was doing physics every day, most of us could walk a few feet down the hall, ask another physiker what he was doing and get completely snowed. For example, I didn't know that propellants were describable by linear equations. Without seeing this formulation, I'm not going to get how the transformation you refer to results in kaboom. Plus, we're now talking about SEE, or whatever, right? Not just what set off the accident round in an open breech.

I'll do some looking for this matrix formulation and I'd appreciate it if you'd post anything you recall about it. This may be 'play', but, at my age, it's also self preservation. Use it or lose it, CRS, sometimes I just get distrac

[felix]

Yes, we are talking, SEE, explosion, detonation, or whatever you want to call it. Energy transformation into wave forms such that something "destructive" happens. In actually the word SEE stands for secondary explosion effect. According to what Larry implies, the powder burns in all cases. Therefore, there is only one explosion, and that is the primer itself. So, by his admission, a SEE is not a SEE by strict definition. ... felix

[georgeld]

Mark/Felix:

Think this thru.
WE don't have access to THAT primer of course.
My question is, did they assume it hadn't fired because there was no firing pin dimple?? OR had it actually not fired??

There's no doubt in the world in my mind that if/when this powder fired, regardless of the cause. That primer also fired from the sparks and/or heat.

My thoughts are this: The primer was tight in place. The bullet was hammered back into the case.

The powder was mashed by the hammering thru the primer hole into the primer anvil and back against the cup setting it off from the open side rather than dimpling the cup from the proper place.

Personally I would believe this is what happened rather than wave's and all that technical stuff. BUT: we'll never know for sure, right?

Quite a discussion, have enjoyed reading it. Thank you,

[felix]

Yes, George, that is possible. But, even if the anvil was broken or not, who can tell what did it? Powder crushing, or the explosion of the powder. If the anvil was still intact, and the plastic coating (if any) over the primer not broken, even microscopically, then we would know for sure the primer was never involved. I personally think the primer was not involved at all because someone prolly would have printed the condition of the primer as being fired, but not punched from the rear in some later issue of some gun rag somewhere including PS. ... felix

[Larry Gibson]

Yes, we are talking, SEE, explosion, detonation, or whatever you want to call it. Energy transformation into wave forms such that something "destructive" happens. In actually the word SEE stands for secondary explosion effect. According to what Larry implies, the powder burns in all cases. Therefore, there is only one explosion, and that is the primer itself. So, by his admission, a SEE is not a SEE by strict definition. ... felix

Felix

I don't imply anything, the "explosion" in SEE refers to the rifle exploding not the powder. The primer does what primers do, the powder does what powders do and when the pressure exceeds the threshold of the rilfe to contain it it explodes. That's not to hard to understand.

Larry Gibson

[missionary5155]

Good morning Setting off primers is very easy from the inside or anvil side... I have experimented ... not very scientificly.... putting pressure on anvils one at a time and discovered it does not take much to make the little rascles pop.
Mike

[felix]

Very hard for me to understand, Larry. I have never blown up the same rifle twice. ... felix

[Larry Gibson]

Very hard for me to understand, Larry. I have never blown up the same rifle twice. ... felix

If the rifle didn't explode then you did not have a complete SEE as the rifle exploding is the key part to the word "Secondary" in SEE (Secondary Explosian Effect). You may have come close but apparently were lucky that the bullet moved before the pressure threshold of the action was reached. Close, but in this case "no cigar" was fortunate. All the indications are there but as I've said I've not seen a documented case of SEE (complete) where a cast bullet was used. I've only seen cases where jacketed bullets were used.

Larry Gibson

[felix]

If blowing up the rifle is the secondary explosion, what was the primary explosion? ... felix

[Larry Gibson]

If blowing up the rifle is the secondary explosion, what was the primary explosion? ... felix

If you read the article it explains it. It is the primer explosion and the beginning or the powder burn that drives the bullet forward into the throat and lands. That is the first exposion. However, the reduced charge of slow burning powder has not yet produced enough pressure for the bullet to keep moving so it gets stuck in the fouled and/or rough throat area. Pressure actually drops a bit at this point as the internal volume has increased faster than the generated gas (remember a slow burning powder here) can maintain the pressure. The powder continues to burn wit pressure building and if the bullet isn't stuck you get the hang fire (click - bang) as the bullet is shot out. You may or may not get signs of excessive pressure depending on whether excessive pressure developed before the bullet moved. If the bullet is stuck and doesn't move (bore obstruction) and the pressure exceeds the structural strength of the action you get the SEE (secondary explosion).

Larry Gibson

[felix]

OK, Larry, that makes it clear on what you are thinking. In that particular situation, if you add one more explosion, the term SEE would have to be termed TEE, for trinary explosion effect: primer, powder, gun. But you said the powder never goes through an explosive state, so you have never seen a TEE by that definition, right? ... felix

[leftiye]

So, the burning rate of powder doesn't go vertical on the graph as pressure rises?

[Larry Gibson]

Felix

I hate to mention this but smokeless powder does not "explode" when ignited by the flame of the primer explosion, it progressively burns. That's why they are all listed by their burning rate not "exploding" rate. The problem appears that you are trying to convince yourself that something makes the powder "explode". The point is, it doesn't.

Larry Gibson

[Larry Gibson]

So, the burning rate of powder doesn't go vertical on the graph as pressure rises?

No, the graph representation of the burning rate of smokeless powder's increase in pressure is not vertical (as in straight up) but progressively increases.

Larry Gibson

[felix]

Larry, are you saying there is no need for a primer to explode? ... felix

[longbow]

I have question for you all.

Back onto the subject of reduced loads and potential problems - where this thread started I think.

I have read many comments pro and con about using small charges of fast powders for reduced loads. It seems to be a common practice and certainly the Lyman Cast Bullet handbook lists many loadings for Red Dot, Green Dot, Unique, Bullseye and others for cast boolit shooting in rifles.

Many of these loads must be less than 50% loading density. This seems to lead to some undesirable situations: large air space allowing primer flash over giving inconsistent ignition and the potential for double charging. Now I understand that some powders are "position insensitive" so the large air space may not be a problem but certainly double charging is.

I also read a lot of negative comments about using cereal or other fillers. Most of the comments seem to be about high pressure and ringing chambers.

Now I would have to agree that using a small charge of powder in a large cartridge with a small bore (say 22-250) and topping up with a cereal filler or shotgun buffer filler might lead to some problems what with the filler having to compress and squeeze through that little neck and also the weight of the filler being significant with respect to a little 40 or 50 gr. boolit.

So ,let's look at another situation that is probably more common - say .303 British with a 200 gr. cast boolit. Similar with .308 Winchester, 30-06, 8mm Mauser, etc.

Here you have a moderate sized body and not too small neck. It seems to me that the benefits of a filler outweigh the disadvantages: takes up all that volume and should improve efficiency with a subsequent increase in pressure but most cast boolit loads are reduced from J bullet loads anyway, protects the boolit base from heat and erosion, cheap (cheaper than gas checks), the weight of filler is realitively small compared to the weight of the boolit certainly for medium to heavy boolits in a 30 cal., eliminates the possiblity of double charging.

I see cartridges developed to reduce case capacity for subsonic or reduced/low velocity loads so loading density is high but this also increases pressure.

What major difference are there in reducing case capacity by reducing size versus reducing case capacity by use of filler? Both result in less case volume and increased pressure for a given charge/boolit weight. The filler adds a little extra mass and possibly a little extra friction.

So far I have used loads for .303 British with 200 gr. boolits, Unique and IMR 4320 powders with and without fillers (working up loads of course) with no signs of pressure and so far better results with than without fillers.

For the Unique I am filling up empty space for a 12 gr. charge and for the 4320 I am reducing the load to 29 grs. but I think got poor ignition or just inconsistent burn with the light load until I added filler.

I guess having said all that what I am asking is for any reduced load in a .303 British, 30-40 Krag, .308. 30-06, 8mm, etc. why would you be better off with an air space- especially if it might result in inconsistent ignition, double charging, detonation/SEE?

I don't want to start an argument, I am just curious.

Longbow

[Larry Gibson]

Larry, are you saying there is no need for a primer to explode? ... felix

Where in the heck did you come up with that from anything I've said?

Larry Gibson

[felix]

"when IGNITED by the flame" ... felix

[Larry Gibson]

"when IGNITED by the flame" ... felix

Well perhaps you might reread a reloding manual or two to refresh your memory, and you might want to pay close attention to the part on how a cartridge fires. The firing pin strikes the primer crushing the priming compound between the cup and the anvil causing it to explode. The flame from the prmer explosion (some call THAT a detonation) goes through the flash hole and guess what? The flame ignites the powder, that's what! All quite elementary my dear Watson.

Larry Gibson

[felix]

Ok, then, no explosion required. The flame ignites the powder. So, all we need is a flame producer. ... felix

[leftiye]

No, the graph representation of the burning rate of smokeless powder's increase in pressure is not vertical (as in straight up) but progressively increases.

Larry Gibson

I believe the correct term is "progressively increases exponentially" and it does eventually go vertical (eventually in a nanosecond). The rate increases (the powder burns faster) at the higher pressures until a high enough pressure comes about that the burning rate is vertical on the graph.

[Larry Gibson]

Ok, then, no explosion required. The flame ignites the powder. So, all we need is a flame producer. ... felix

Ok Felix, this has turned to the sublime. You've pulled my leg enough.

Larry Gibson

[Larry Gibson]

I believe the correct term is "progressively increases exponentially" and it does eventually go vertical (eventually in a nanosecond). The rate increases (the powder burns faster) at the higher pressures until a high enough pressure comes about that the burning rate is vertical on the graph.

In the oscilliscope graphs I've seen (unfortuneately I wasn't able to copy the one for the article) I don't recall a vertical line but then a nanoseconds worth may not have shown or I may not have noticed. Sounds reasonable enough when the pressure spikes during a very high pressure explosion. But even with the explosion of the primer on the graphs show a "progressive increase exponentially".

Larry Gibson

[felix]

Agreed, Larry! Mutual right to think as one does. Many views of the same thing. One of these days mental telepathy will become the language of choice. ... felix

[leftiye]

Larry,

I appreciate your tolerance. Whether or not the particulars are absolutely correct or not, I think the process is well established. In fact I think that perhaps the most important (or one of the most important) understanding in reloading is based on this concept. That being how to judge when a working maximum pressure has been reached (and to cease to try more powder rather than harm gun & self). Puristically this understanding is based on understanding that the burning rate is about to become out of control due to high pressures demonstrated by previous loading.

Powders do all burn faster the higher the pressure is. What happens when they go above the recommended pressures in the burning rate graphs? Are they still linear? Alternatively, what is the burning rate of powder X at 120,000 psi. just before the reciever lets go? Whatever it is, it wasn't ever expected to be utilized with that powder, and probably closely resembles an explosion.

[uscra112]

A bit late this party, but let me add the following scraps of info. I've been wondering about this "detonation" legend for years.

1.) The term for what our powder does is "deflagrate". Meaning the molecules of
the material re-arrange themselves in the presence of heat, with an exothermic result, and the evolution of large amounts of gas. The heat keeps the process going. Also, Boyle's Law says that increased pressure in a gas without proportionally increased volume makes the gas hotter all by itself.

2.) Detonation, as the High Explosive guys define it, is the case where the molecules of a material re-arrange themselves when they receive a shock. It does NOT require heat. The result is the very sudden evolution of very large amounts of gas, and thus an extreme pressure pulse, even in open air. What makes the H.E. detonation so devastating is that extreme suddenness with which the whole mass changes state, and the suddenness comes because the shock wave propagates at extreme speeds. (Many thousands of feet per second, if I remember right).

3. ) Detonation as the infernal combustion engine guys (i.e. me) define it, is a different matter. We define detonation as a case where the fuel-air charge in the cylinder begins to ignite spontaneously in more than one spot due to high pressure AND heat radiation, (from the initial flame front at the plug), combining to create new ignition spots where there shouldn't be any. The charge burns much faster than it should, but it still ain't detonation in the HE sense. It DOES create extreme pressures in the cylinder though, and can punch through pistons, crush rods, and mash bearings like they were putty.

THAT SAID:

A small charge of pistol powder in a large case has never, to my knowledge, been shown to blow up a gun. There just ain't enough material in the available in the charge to create that much gas.

But the case of some SLOW powders blowing up a gun when the charge is too small MAY approximate the I.C. engine case. In a large case completely full of powder, the deflagration proceeds from the point of ignition through the charge in a "flame front" until it's all consumed. Just like an engine. This is because it is HEAT that sets the powder grain to deflagrating, not shock or pressure. The rate of deflagration DOES increase if the pressure rises, so we kinda hope the bullet is going down the barl fast enough to keep the volume expanding and the pressure curve in reasonable territory. This why loading density matters. Low loading densities can lead to less consistancy in flame-front propagation.

Back around WW2 there were experiments (Elmer Keith was involved, wouldn't you know it!) at trying to utilize this fact by extending a tube from the primer to the front of the case, so as to start the deflagration from the FRONT. They then also loaded two different powders, one slow (in front) and one faster (in back). This was an an effort to lengthen the time that there was high pressure in the barrel, and thus get higher velocities without extreme peak pressures. After all, the total impulse to the boolit is the INTEGRAL under that pressure curve. This scheme exactly duplicates the way these big compressed-air pumpkin cannon work. (The "Second Amendment" cannon gets tested every year near my house. They start their vegetable "boolit" down the barrel with low pressure, then when its partway down and moving they release a second high-pressure tank into the breech. If they hit it with the high pressure too soon, they get "pie filling". BTW they actually use melons, not pumpkins.)

This "duplex loading" turned out to be a dangerous dead end, and wasn't continued. The point of mentioning all this is to support my contention that there is a "flame front" that propagates through large charges of powder.

NOW - consider the case where a less-than-caseload charge of a "slow" powder is ignited. Because it's not a case-full, the primer blast scatters the charge out, and it ignites at several different locations within the volume. The time for the whole charge to deflagrate is less, because there's multiple flame fronts. It may also be that the scattered powder allows radiation from the back of the case to reach the front, to aggravate the problem. So the mechanism may be just like "detonation" in an engine. A big charge of one of those "slow" powders contains a LOT of energy waiting to be released. If this mechanism as I've suggested it can get the process going too fast, it CAN blow up the gun.

But it has nothing to do with "wave mechanics". This "wave mechanics" thing comes from the confusion of terms. The H.E. guys work with materials that will turn from solid to gas in microseconds when hit by a shock wave, and they call that "detonation". Our propellants WILL NOT "detonate" in that sense. The atoms are not arranged that way. But they CAN "detonate" in the I.C. engine sense, and make a bloody mess doing it.

Now, why is it that the powders that seem susceptible to this are always "ball" powders? Extruded powders with a hole thru the middle are made that way to help control the deflagration rate. Deflagration takes place only on the surface of the grain. To slow the powder down, and thus broaden that pressure curve and reduce the peak pressure, the hollow tube form was developed. The surface area inside the tube starts out small, and gets larger as the deflagrated material (gas) blows away. Thus, it has less opportunity to create a sudden, early pressure spike. Ball powders are solid. Their geometry is exactly backwards. They start with the largest area, and burn down to a small area. To control this, the powder has a coating that inhibits the early deflagration rate. Is it possible that in the presence of higher than normal pressures this delaying mechanism breaks down? I'm not a chemist, just a greasy-fingernail Mechanical penguineer. Somebody get me a grant.

BTW ball powders were developed as a low-cost way to recycle salvage powder during the war. Phil Sharpe wrote a VERY detailed explanation in his book 'A Complete Guide to Handloading." If you can find a copy, buy it. I will sell you mine for about half a million USD.

[floodgate]

uscra112:

Good discussion!. I'm not so well up on the auto engine stuff, but I did work on military pyrotechnics and shaped charges* with some talented "powder monkeys" some 40 years back, and did quite a lot of reading on the topic. The "technical" definition of "detonation" - applied to a single solid grain of explosive at least - is that the flame front propagates at a speed in excess of the speed of sound IN THE EXPLOSIVE MEDIUM - typically around 25,000 feet per second (sound velocity goes up as the density of the medium increases; much faster in TNT than the 1100+/- fps in air). But this "technical definition" is a bit hard to apply to a loose charge of small individual grains, so we're still doing "informed guesswork".

floodgate

* One of the most awesome sights I have ever seen was a 60" stack of battleship armor plate with a hole clear through it (about 1/4" at the far end, but you could still see light through it) from an experimental shaped charge. YIKES!!!

[longbow]

uscra112:

That is one of the best descriptions and explanations I have heard yet and makes a lot of sense to me. I have often wondered if the problem was due to primer flash over, or whatever you want to call it, igniting a large surface of exposed powder - multiple ignition points - for a powder that was designed to burn at high loading density with "end on" ignition.

If you didn't see my question above please scroll up and take a look. Your explanation is basically why I asked the question about fillers to effectively maintain a high loading density with reduced charges of slow burning powder.

If you have any comments or explanations I would appreciate your input - and form others as well.

Thanks,
Longbow

[uscra112]

I've messed with fillers, and I came to the same conclusion as Col. Harrison did. As someone pointed out, non-combustible solid granular fillers like cream of wheat have to crowd thru the case neck, so they're not a good idea for bottleneck cases. Pressures can go very high. In a straight case, they're probably less trouble, but I did all my experiments with the .35 Remington case. Even in a straight case, they still constitute extra mass that has to be moved, and that means higher pressures.

Harrison and I agree that the best "filler" is Kapok or Dacron fibers. Between 1/2 grain and 1.5 grains will keep the powder back against the primer, and assure better and more consistent ignition and deflagration rates. The filler all vaporizes in the case, and leaves the gun as gas, unless the load is very low, or you've used too much of it. No pressure spikes.

I've messed about with this XMP5744 powder quite a bit. It's got about the burn rate of 4227, and it really is the right stuff for low-density loadings. How they do it I do not know, except that I surmise that the secret must be in the coating. Fundamentally it's a pretty energetic material, something like 20% nitroglycerine. Maybe if Winchester could license the XMP5744 secret, the ball powders would not be so dangerous. Until then, I'll burn lots of XMP5744 for my lead boolit loads.

[georgeld]

Larry G:
Just read your: "powder doesn't explode".
Ok, I agree there. BUT: some yrs ago after I hadn't reloaded for about 20+yrs.
Dad was storing my equipment and leftover powder for about 20lbs of 50 cent and buck a pound mostly 4895 & 4831.

He wanted to 'develope a seeping spring' in the pasture. Believing he could do that by blowing it up with dynamite he bought five sticks. Also, believing I'd never get back into reloading again he wanted to get rid of my gun powder. SO: put the sticks in the hole's, poured all that fine powder down around it. Then covered it up with a bunch of dirt and big rocks and set her off.

When the wash tub sized boulders and dust quit flying overhead at 120yds or so. He went to check it out and not only found quite a stream flowing, but, quite a pond blown out too. He'd borrowed a loader to do some digging, but, didn't need it.

IF smokeless powder don't explode. Even with detonation exposed by the dynamite. What happened?? Surely all that smokeless fired mighty suddenly also.

Longbow: You've asked about filler and lite charges of shotgun powders. I used CoW on top of 10gr bullseye in .223 brass to make .222mag cases stopped the neck up with TP and fired it in the air. The headspace was in excess enough the primers were kicked about halfway out because the shoulder didn't contact the chamber. After about 50 I gave up and just loaded them about min. with standard loads and they came out perfect then and accuracy wasn't too bad either.

I also load lots of '06 with 4-7gr Red Dot and no filler at all under a 115gr cast slug for plinkers. They're great for women and kids to learn how to shoot the big guns without getting hurt by recoil. They're also very accurate out to about 100 feet then they get too slow and go wild. Although I've never used them for it, they'd be perfect for rabbits or such up close. Say, carry a few in your pocket while out elk hunting for when blue grouse are seen setting around begging to be shot for camp meat. It's rather exasperating to be out hunting and have someone fire off some full charge'd mag's and come back to camp with a grouse or two. That's what pistols are for, but, not everyone carry's one.

Great discussion,

[DOUBLEJK]

George
5 sticks a TNT detonated in paked wet ground is quite a sight all by itself...
Water being the uncompressible mass it is tranfers energy rather well...
I imagine that powder probably ignighted but doubt it added much depth or area to the pond....
Ya aught see what a 50# bag of Phosphate fertilizer... 1 3lb. coffee can of diesel soaked sawdust n a blastin' cap will dig....:-D

[Larry Gibson]

leftiye

I don't recall seeing a oscilliscope graphs made uder the circumstance you describe. Not to say there aren't any as I'd bet ballistic labs do have them. The info probably is not released as the tests were no doubt conducted by the manufactures of the ammo, actions or powders and are close hold secrets. What you say makes sense to me. Another thing to remember in these is that the metal (the firearm actions in our discusion) exhibits different charactoristics when it is shattered froman explosion vs bursting from over pressure. The metalurgists can determine which quite readily.

You are quite right that understanding and reading pressure signs correctly, particularly with a gronograph. You can readily judge when the pressures get erratic or inconsistant when a working maximum pressure has been reached as you say. It is the learning how to read and judge this that is important. Thanks for the enlightening discussion.

Larry Gibson

[PatMarlin]

I know of no documented SEE with a cast bullet.

Larry Gibson

I read the article on the SEE as someone emailed it to me, and it's very interesting and makes sense to me, but what about cast boolits? Does it happen, or is it just that it hasn't been documented?

Also what about the effects of throat errosion mentioned in the article where cast boolits are concerned?

[PatMarlin]

Suggestions from Richard Lee in his book Modern Reloading. Loading a reduced "too Little" powder charge load with very slow powder and large rifle cases can be a dangerous pressure spike situation, so he offers this info... Quote-

"A very conservative guide line would be to limit charge reduction to 20% for the slowest powder on the Burning Rate Chart (he's refering to the burning rate chart listed in his book which is an extensive list of common powders). You may increase the reduction by 1% for each preceeding 30 powders on the chart. Limit total reduction to 50% for the rest except for greatly reduced squib loads. Load these with a very fast but extremely light load."

[Larry Gibson]

georgeld

DOUBLEJK's explanation is pretty much right on. Most dynomite is used as a "pusher" because the explosive velocity is low enough the it pushes instead of shatters. A lot of dirt can be moved, as you witnessed, with 5 sticks. Particularly if there is a water base underneath. This is somewhat an inverse "tamping" effect and multiplies the total force of the explosion by directing it up and out in this case.

Larry Gibson.

[Larry Gibson]

uscra112

Interesting treatise but I've a couple points or questions. I question whether the "flame-front propagation" theory will hunt. First of all to my knowledge it has not been reproduced under controlled conditions. Second, the SEE occurs when a slow burning powder (for the case volume) is used. These are harder to ingnite because of the flame retardents put on/in them to retard burning. It's what makes the "slow" burning. Thus wouldn't a reduced charge of a medium burning powder with the flame (heat) blowing through it be more suseptible to "flame-front propagation" simply because it is esier to ignite? Following that it would seem to me that a 60 to 70% loading density of 4895 would be a very dangerous thing. However it is not.

Also I must disagree with "Now, why is it that the powders that seem susceptible to this are always "ball" powders?" If one is old enough to remember or does some research you will find this SEE problem surface with the availability of surplus 4831. It was so cheap many wanted to used it for everything. The first cases of reported SEE most often involved the 25-06 (considered an "overbore" cartridge back then), the lighter weight varmint bullets (85-100 gr) and reduced or "starting loads" of surplus 4831. There have been numerous other slow burning extruded powders involved in SEE before the problem or warnings about the same potential with ball powders surfaced.

Larry Gibson

[Larry Gibson]

I read the article on the SEE as someone emailed it to me, and it's very interesting and makes sense to me, but what about cast boolits? Does it happen, or is it just that it hasn't been documented?

Also what about the effects of throat errosion mentioned in the article where cast boolits are concerned?

I would think that the same conditions that cause the SEE with jacketed bullets could very well happen with cast bullets. Felix's reported example may have been one. However, I don't think an SEE has been reported with the use of cast bullets because the complete SEE did not happen. There is a certain point with a lead bullet, even a hard cast heat treated bullet, where it's shear strength will give way and it will strip, flow, bend or whatever and move. This "shear" limit of a stuck cast bullet is much, much below that of a stuck jacketed bullet. This "shear" limit also occurs with cast bullets at a pressure level that is below the structural integrety limit of the actions or even perhaps the brass cartridge cases. Thus the cast bullet that gets stuck in the throat is shot out before the pressure goes over the limit and the SEE occurs. My thoughts on why we haven't a documented case of SEE with cast bullets anyway.

Larry Gibson

[felix]

The two grades of dynamite used most often is 40 percent (nitroglycerin) and 80 percent. Sawdust (big chip) is used as the carrier when made by DuPont (used to be). 40 percent is the stump remover, like when clearing land; 80 percent used to crack big rocks, like when making a road through the hills/mountains. Both grades require blasting caps (explosive) for reliable ignition. It is very dangerous not to include the caps on the fuse, because of the hang-fire probability. ... felix

[Ricochet]

uscra112, there are a couple of points I'll disagree with you on. One, "detonation" or "SEE" is definitely not confined to Ball powders. The best known reports were with reduced charges of IMR 4831 in .25-06.

Secondly, though smokeless propellants deflagrate in normal use, that does NOT mean that they are incapable of detonation. There is no clear defining line between substances that detonate and substances that deflagrate. It usually depends on the circumstances of initiation. Plain guncotton is a high explosive, and used to be used that way a great deal. Even when kept wet to make it less sensitive, it detonates with great violence when initiated with a blasting cap. On the other hand, dynamite will usually burn quietly when ignited with a flame.

"Gelatinizing" nitrocelluose with a solvent or nitroglycerine was found to desensitize it so it would deflagrate as a propellant instead of detonating. (Many explosives can similarly be "dead pressed" to high density under pressure and become very difficult to detonate.) But that doesn't mean it won't explode if initiated with a high explosive, as in the case with the dynamite above.

Pretty much every explosive or propellant can be detonated by impact. There are standard tests involving dropping steel weights on a sample on an anvil, rating them by height. Some obviously are way more sensitive than others, but that doesn't mean the "safe" ones are incapable of shock detonation.

Gen. Hatcher, in his Notebook, relates an interesting story of a soldier assigned for some reason to fire .30-06 ball rounds through a large can of smokeless powder who was bowled over by the blast when the bullet impact detonated the powder.

Deflagration is a process the rate of which is influenced by the temperature of the solid propellant before ignition as well as the transfer of heat to the surface by convection/conduction from the hot gas surrounding the propellant grains and radiation from the incandescent gases and particles. If the propellant is hot, deflagration proceeds at a much faster rate. We know that from shooting the same loads in winter and summer. This is the basis for my hypothesis of hangfires (or the situation in the Handloader article with the bullet initially moving out at low gas pressure and then hanging up down the bore) producing a condition where much of the deterrent-coated powder doesn't ignite immediately, but is surrounded by hot gas that heats the unignited powder so it's already quite warm when it finally does ignite. Then it burns far more rapidly than its usual rate, causing a very steep pressure rise.

[TAWILDCATT]

I've been doing some powder research for my next reloads, and I'm excited at the prospect of using Trail Boss. TB is recommended for cast boolits and low velocity loads, both of which I'm trying to achieve for C.A.S. when the wife and I get into the sport later this year (have to buy some guns to shoot!) My new LEE mould arrived yesterday, a 358-125-RF. A nice light bullet with a flat face, good for most target work. Hodgdon says in their load data for a 125 bullet 3.0 gr. of TB will give a velocity of 753 at 11.600 psi. I'd like to shoot this 125 bullet closer to wad cutter velocity of around 650 fps. When you start reducing loads by 10% or 15%, do you just get lower velocities, or do other factors come into play that I'm not seeing? I do know that if you get too small of a load, that detonation can occur. This doesn't seem likely being Trail Boss is so bulky and fills the case. Any opinions on reduced loads of Trail Boss? Testing will be done using a Ruger New Model Blackhawk with a 4 5/8's length barrel.
Ohio Rusty

I use 13 gr red dot in 30/06 and other military rds with 170gr lead boolits at 1680fs its when you use slow burning powder there are problems.should have 60% capacity with those.deep discusions muddy the water:Fire: :Fire:

[Larry Gibson]

Ricochet

"Gen. Hatcher, in his Notebook, relates an interesting story of a soldier assigned for some reason to fire .30-06 ball rounds through a large can of smokeless powder who was bowled over by the blast when the bullet impact detonated the powder. "

Page or chapter that is in, I can't find it.

Larry Gibson

[longbow]

uscra112:

Thanks for the response.

I'm not so much thinking about granular fillers for really small loads of fast powders, more for reduced loads of slow powders. It seems the general consensus is that reducing slow powders much below minimum loading book recommendations results in poor accuracy and may lead to dangerous pressures - SEE, detonation or whatever mechanism occurs.

I guess my thought is quite simply that with a reduced load (below book minimum but not as low as 10 or 15 grs. in say a 30-06) of relatively slow powder there is a lot of air space so chance for poor ignition, mutliple ignition points, etc.. By adding filler the air space is eliminated so ignition and performance should be improved and of course pressure will increase - but that would happen in a smaller volume cratridge or with higher loading density in what is being used.

About the filler being squeezed through the neck of the cartridge I certainly can't argue but then what happens to a case full of really slow burning powder? It doesn't all burn in the case so must also be compressed and squeezed through the neck and until it burns it is also a dead mass being pushed up the barrel behind the boolit.

Again, I am not arguing with anyone just looking for answers and opinions.

Thanks,
Longbow

[felix]

The only real answer is to fill the case up, and even that is not failsafe. ... felix

[uscra112]

Thanks for helping my eddication along, guys. I've never been a hell-for-leather, big-cartridge shooter, nor am I a milsurp powder devotee, so my reading missed the info about 4831.

And I'm only hypothesizing about this anyway. It makes sense to me because I'm so familiar with I.C. engines. Racers are always running on the ragged edge. If they're not, they're giving up power. So as I think I mentioned, when I took up reloading and started reading, the similarity jumped out at me. To push the velocity limit, you push the pressure limit. Push it too far, and you got a problem.

The only way we'll ever know anything concrete about this SEE is when somebody can devote the time and resources to instrument a few barrels, build a bunker with remote controls, and then try to MAKE them do the SEE thing. Once you can reproduce a phenomenon, you know something about it, and you can study it to learn more.

I'd love to be the guy - instrumentation and measurement has been a passion since my first real job in 1966, building spectrometers and polar nephelometers. (Yes, there is such a thing, and you know what one is, that makes two of us on the planet.) But I'm too poor and over-employed, so it'll have to fall to someone else.

I can't even completely rule out "wave" hypotheses from my thought experiments. Gas dynamics being what they are, maybe you could get two pressure waves inside the case to interfere in such a way as to get a very high pressure in just part of the case volume for a microsecond or three. That would also spike pressures by increasing the deflagration rate in that part of the volume by some large factor. How this would happen I can't imagine, but I won't say it can't happen. The math I used to read about for chamber design probably wouldn't be relevent, because none of those had internal pressures of 50,000 PSI, nor were they full of nitrocellulose looking to be something else. The guys who run top fuel drag racers are pretty close - the charge in their combustion chambers is almost all liquid at TDC, I'm told, and it's alcohol and oxidizer, not too far from our propellants, chemically. Some cosmologist who can model plasma behaviour in stars might have an idea. Know any?

[felix]

With your background as exhibited, it might help some to think about oily rags catching fire all by themelves, and how you would formulate the circumstance in mathematical terms. ... felix

[Ricochet]

Ricochet

"Gen. Hatcher, in his Notebook, relates an interesting story of a soldier assigned for some reason to fire .30-06 ball rounds through a large can of smokeless powder who was bowled over by the blast when the bullet impact detonated the powder. "

Page or chapter that is in, I can't find it.

Larry Gibson
Hatcher's Notebook is chock full of interesting stuff that's terribly hard to go back and find later. In my Third Edition it's in Chapter XXI, Explosions and Powder Fires, pp. 527-8, in the subheading Ignition of Powder by Rifle Bullets. It's short enough to quote in full:

"Right after World War I some mysterious magazine fires occurred, which were laid to bullets from careless hunters, and it was decided to see if a rifle bullet fired into a large can of powder could set it off. Some experiments were conducted in which large cans (150 lbs.) of smokeless powder were fired at with Springfield rifles. It was found that sometimes such a bullet would ignite the powder. In one such test, the firer got a surprise, for this time he seated himself about 100 feet away and fired into the very bottom of the can. Instead of igniting, it exploded with great violence, and turned the startled firer end over end. It seems that if there is more than about 2 feet of powder above the point of entrance of the bullet, the powder may explode instead of simply burning."

[Larry Gibson]

Hatcher's Notebook is chock full of interesting stuff that's terribly hard to go back and find later. In my Third Edition it's in Chapter XXI, Explosions and Powder Fires, pp. 527-8, in the subheading Ignition of Powder by Rifle Bullets.

I don't have the third edition that was published after Hatcher's death, my edition does not contain that information. It would be interesting to have more back ground on the type of powder used back then vs powders now days as there has been much improvement. I can say is in the early '70s in Oregon there were several legislative "explosive" bills that would have severely controlled and limited possesion of black and smokeless powder. A dealer provided numerous cans powder from Bullseye on up through 4831 in burning rate. We shot them with a .220 Swift to give the powder the most "shock". All we managed to do was fertilize the area around the cans of powder. No explosions but then I guess we didn't use 150 pound kegs, may have been a reason there. I also know that I've been through two wars an numerous crappy places in between. I have had ammunition in magazines shot off me and seen numerous other types of small arms amunition that has been shot. I've never heard of it exploding nor even heard any barracks BS about in in 42 years of Army service.

There have been all sorts of theories regarding what occurs when a gun blows up for some unknown reason. All are still theories except two of them. Those two have been proven in laboratories by repeatable tests. Those two are; Bullseye does "detonate" when used in small quanities and SEE is caused by the bullet becoming a bore obstruction. I will go with proven facts thank you. You may go with whatever other theories you wish.

Larry Gibson

[uscra112]

Larry, can you cite the testing that showed that SEE is a bore obstruction problem? That would probably shoot down my homegrown theory.

[Larry Gibson]

Larry, can you cite the testing that showed that SEE is a bore obstruction problem? That would probably shoot down my homegrown theory.

Emailed the article to you.

Larry Gibson

[felix]

The scenario:

Two new guns, a 270W Sako AV, and a 243W Kimber 84B, both having been shot less than a couple of hundred rounds at most with factory ammo. Guns delivered were previously sighted by the owner, the Sako at approx 200, and the Kinber at exactly 100 as determined by me. The owner indicated complete satisfaction with the factory loads in each gun, but desired an inventory of equivalent ammo cheaper.

DP85 powder was selected as being the best compromise for each gun. Remington Core-Lokts were selected: 130 grainers for the Sako, 100 grainers for the Kimber.
Cases were from the owner and others obtained from folks on the board. Primers I had on hand.

Sized fully and washed the cases throughly, checked lengths to be within 0.010, and separated by brand. Dummy rounds were made to seat the respective bullets to 0.010 off of a land jam. Typical condom loading for me is to show a magic marker scrape (very minor scrape) around the circumference of the bullet upon complete bolt closure. These rounds exhibited exactly that. Good to go.

Powder speed reported to be between 4350 and 4831. It is a ball powder with multi-sized granules. I chose 55 grains for the 270, one grain over suggested for a 150 grain bullet printed as such on the black plastic container from Powder Valley. I chose the Federal Magnum LR primer. Loaded 5 rounds and went to the river, 7 miles from the house. The rounds shot left and high of my standard 100 yard mark, but were entire consistent. Came home and cleaned gun. Lots of copper. Load too hot? Yes, after checking cases. Cases used miked 0.465 on the body just above the extractor groove BEFORE shooting, and AFTER were 0.468.

Different day, loaded 5 new miked cases with 53 grains. They shot 0.467, a difference of 0.002 from initial. Still to hot. Walked the scope 3 inches to the right, and 1.5 inches down during the shoot. Being a left handed gun, that was OK, because I am right handed. The cheek piece on the stock might be grabbing the gun wrong. Keep in mind the gun was sighted by the owner for 200 yards and I was shooting at a hunnert.

Different day, loaded 5 new miked cases with 51 grains, and changed primer to Rem standard LR. Each shot took out a rock from a third to a half the size of the small X in the Loopy 3.5-10 scope set at 10 power with ZERO parallax. I was happy as that exceeded the owner's expectation by far. The rocks blew up as if an atomic bomb hit them. I was indeed lucky to see it through the scope because of the recoil. (I hate recoil!!!! Youse guys with those 45-70's can have all of the rock-n-roll you want!!!! More power to ya'll.)

Bingo-bango, we have a load as I thought driving home. Oooops! Measured the cases: differences of 0.001-2-2-1-4. So what, wrote the 0.004 case off as a soft case because each shot hit the target right on.

Loaded the next sequence, going back to the magnum primer. This time the accuracy was the same not moving the scope one iota, but one round popped a primer. Not good.

Shot the 243 with 38 grains using the same magnum primer. No case expansion, no excess copper. Not even a scope adjustment. It is a right handed gun with a 3.5-10 Grand Slam Weaver. I hit the same relative sized rocks as intended, even with the parallax not correct and showing some fuzziness too. (At 50 yards, the scope is perfect in 85 degree heat. Set at factory to be error free at 100 yards in room temperature). Load is perfect as is.

Loaded up 10 for each gun with cases already shot, and miked. Using the magnum primer for all 20 rounds. Purpose of the shoot was to obtain hold-over amounts. On the fourth shot with the Sako the extractor was detatched. The three previous cases shot measured exactly 0.467, and the fourth: 0.483!!!

Came home to see my friendly smithy who put the extractor back on the bolt.
Pulled the remaining 270 ammo. Going to another powder for this 270.

Will do the 243 in the next couple of days.

... felix

[Ricochet]

Felix, how consistently mixed are the different size grains in that ball powder?

I've read on the Web that WW630 got pulled off the market for issues of inconsistent mixing or separation of different granulations that were supposed to be mixed together to give an appropriate average burning rate.

It's an interesting physical problem to mix together granular solids. Not nearly as simple as it appears.

[felix]

You heard right about 630. I made mention of that some time ago. Well, this powder is a mixture for sure with some really small granules and some really large ones in comparison. What is disturbing is that the powder bridged twice during 60 loadings. The powder also looks like it had an oil spill, i.e., rainbow colors on the concrete, when you look at it inside of a filled case. That would be the nitroglycerin, and in my opinion that should not be obvious. If the powder is "wet" and stored for some time in a case, that powder will turn into concrete within the case. All kinds of ES is the result of shooting the rounds so effected. Corky and I are researching this further. He has a jug of the same lot. Hopefully, his is clean because it is a useful speed in what we are doing. If his is corrupted as I THINK mine is, we have to make further arrangements. Use it fast, dump it, and/or alert PowderValley for a recall. ... felix

[runfiverun]

i would be very leery of a powder of mixed granule sizes. as any type of vibration,
like cars passing the house, could cause you to have a jug that got progressively faster as
you used it's contents.
shudder......i make my own problems............don't need that type of help.