Detonation ?
What is the general consensus among experienced loaders when it comes to "light loads" and so called detonation ? Does light powder volume versus remaining case volume increase the chances of a round detonating in such a manner as to spike pressure to the point of destroying a handgun?
One example I was given is when a minimum powder load is shifted in a case such as when the barrel is pointed down and then the gun is fired, the position or lay of the powder can have several flash points thereby increasing pressure. Is this common ?
One example I was given is when a minimum powder load is shifted in a case such as when the barrel is pointed down and then the gun is fired, the position or lay of the powder can have several flash points thereby increasing pressure. Is this common ?
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XXCross -- Congratulations for holding your own in this technical discussion. By reading your comments it appears to me that you have worked in ballistics RDT&E. Good deal. During my career I also was involved in RDT&E associated with tank guns. You and JustC gave very well balanced and supportable information. And, of course, you are absolutely correct about using X-ray flash photography for viewing ammunition, weapons components, as well as instrumentation at the target head. While this on-going discussion dealt only with relatively basic concepts of propellant ignition, it would be interesting to read comments by unknowledgeable people regarding more advanced subjects, such as ATGM warheads and their performance on various target arrays. That could be real entertaining reading. 0 -
Umm...THANK YOU (beads of sweat running down my forehead). Actually I was never directly involved with the test data gathering , but I did eat lunch with a couple of guys that were. My task was to build the devices that got the job done. (hence my firsthand knowledge of how we know what goes on in the chamber of a gun at the time of firing..albeit a large gun) Would you believe they actually photograph the ignition sequence of nuclear warheads ! It was interesting work and not likely to be duplicated in the civilian market.....WAY pricy...unless you're spending the taxpayers money. (joke, eh) Anyone care to open another juicy topic ? 0 -
OK XXCross, glad to have you aboard this site. I do know about the photos of the nuclear warhead tests. It is pretty amazing to see. I happen to like tank gun and ATGM tets, especially tandem warheads and top attack muntions. 0 -
quote:Originally posted by XXCross
Thank you JustC, I feel vindicated.
Rocky, in the loads you are referring to, the loading still has a density of 70% to 80% or better. (you can still hear it rattle) Loadings that are prone to detonation are in the 25% or less category. It is not so much the "available energy" as the rate at which it comes to bear that causes the damage. (aka shockwave)
I agree with JustC. However, the loads you need to watch out for are not the 25% and below, they are the 25%-60% loads with slow powders. I have used 25% or less loads on a number of occasions to pop out a bullet stuck in the barrel from primer or super light load discharge. At that light of powder load the primer does flash across the entire powder charge and ignites it all. However, the reduced load doesn't give enough pressure to damage the gun. Only enough to remove the bullet from the barrel. Above 25%, and especially closest to about 50%, the charge can produce enough pressure to damage the firearm.
Rocky,
I don't know how you come to believe that smokeless powder in a contained case does not "burn" It burns just like a cigar...only about 21,000 times faster. Which as heat is released gives us that nice high pressure curve by which we can launch bullets. Because we contain that pressure momentarily in a brass case.
I can give you a like example of that in C4. I can take the same amount of C4 and in three different configurations, cut a tree in half, blow a hole through the middle of it, or detonate (burn at an extremely high rate of speed) it with minimal damage to the tree. It's because the compound burns directionally that I could do that. Smokeless gunpowder burns directionally, That's why we can use it to push bullets so fast.0 -
I don't know where you think I said gunpowder doesn't burn. It most certainly does. It just doesn't burn in a cartridge case like a cigar.
Blowups in Cowboy loads are due to double-charging, not SEE. If the primer blast (it is absofrickinglutely not a "spark") across a light charge of fast powder causes SEE, then why DOESN'T it happen in thousands and thousand of handgun firings and almost all rifle firings?
Nobody here has yet explained how their pet theory does NOT cause SEE most of the time.
Oh, since we're tossing qualifications out there, I speak regularly with genuine ballistic experts in the small arms industry. Not nuclear energy, not military explosives and not "something I heard somewhere." I even eat lunch with them. NONE of them give the ideas here much weight.0 -
Perhaps the enraptured members on this thread would like to learn how and why internal ballistics catastrophically blow out a revolver's cyclinder in locations ranging from horizontal-left, to various minutes of arc vertical, and to horizontal-right, BUT do not blow cylinders below horizontal. All photographs that I have seen of blown out cyclinders showed the damage at or above the horizontal plane, and not below the horizontal plane. Perhaps there is a scientific, ballistician's explanation for this observable effect. It appears that Rocky is more knowledgable than anyone else on this subject. I for one would appreciate learning the explanation. 0 -
cowboy action loads are in strait wall cases, which operate at less pressure due to no bottleneck. When you put that fast powder into a bottlenecked case (which was produced with the purpose of increasing pressure by forcing "x" amount of propellant/plasma through an opening of "y" dia, which is less than the diameter of the case) you get the possibility of SEE since pressure will build to higher amounts, and the pressure curve will also sharply increase simultaneously. 0 -
I think I'll just sit this one out. 0 -
quote:Originally posted by Bergtreffer
Perhaps the enraptured members on this thread would like to learn how and why internal ballistics catastrophically blow out a revolver's cyclinder in locations ranging from horizontal-left, to various minutes of arc vertical, and to horizontal-right, BUT do not blow cylinders below horizontal. All photographs that I have seen of blown out cyclinders showed the damage at or above the horizontal plane, and not below the horizontal plane. Perhaps there is a scientific, ballistician's explanation for this observable effect. It appears that Rocky is more knowledgable than anyone else on this subject. I for one would appreciate learning the explanation.
It's because the strongest part of a revolver is the bottom. And, the weakest part is the top. If you look at the rifle that tailgunner put up you will see most of the damage went downward. Another picture a short while ago showed a rifle, a Mosin-Nagant I believe, that had the bottom blown out of it. That's where the gas and pressure is designed to go in case of catastrophic failure.0 -
I think maybe we've gotten some things confused. SEE (Secondary Explosion Effect) is a completely different phenomena from an overpressure burst. Just because a gun ruptures does NOT mean there was a SEE occurrence.
SEE involves a secondary explosion, generally thought to involve a reflecting and self-amplifying pressure wave within the case. The mechanism causing it is not understood, but the effect can be reproduced sporadically in the lab.
Another not well understood phenomenon involves a hang-fire, loss of propellant deterrent coating, and re-ignition at a greatly increased burn rate. This is what happens in handgun rounds using reduced charges of H110/W296. It is believed that the primer fails to generate enough heat and pressure for ignition, but does displace the deterrent coating. After a noticeable hang-fire of less than a second, the powder does ignite (probably due to still-incandescent primer particles) but without a deterrent coating, burns instantaneously. Here's a photo of a reduced H110 that fortunately did not re-ignite:
You can see the natural greenish-yellow of the propellant absent its darker deterrent.
Finally, there are over-pressure bursts caused by double-charges, wrong powder or foreign matter (like tumbling media) in the case. These are neither mysterious nor misunderstood: they are simple mistakes.
Revolvers lose the top three chambers and the topstrap mainly because the first chamber to burst directs its energy in all directions, but that energy is quickly dissipated. There is enough to burst the top chamber and peel away the two adjacent ones, but by then the pressure is exhausted. If the event were a true explosion, with supersonic shock waves, the destruction would be much greater. In fact, the classic three chamber burst is almost definitive proof that what happened was NOT a true detonation but only an over-pressure firing.
Here's another photo of one in action, for your enlightenment:0 -
I had a 'flashover' today with my BFR in 45/70. Primer lit, flashed over the powder, bullet lodged halfway in the cylinder and half in the barrel. Load was a federal Magnum large pistol primer, 32.5 grains of SR 4759 under a heavily crimped 300 grain JHP. Powder had a greenish tint to it when I broke down the round. This has NEVER happened to me in over 25 years of reloading. Primers and powder were new manufacture. I'm still stumped.
10-15 years ago, I spoke with Homer Powley over the phone for about an hour. One of the questions I asked him was about detonation,( I was trying to work up safe smokeless loads for a 45/120). He told me in no uncertain terms that in all his years in the field he had never seen it. He also stated he'd never been able to duplicate it in the lab. Dave0 -
quote:Originally posted by torizus
What is the general consensus among experienced loaders when it comes to "light loads" and so called detonation ? Does light powder volume versus remaining case volume increase the chances of a round detonating in such a manner as to spike pressure to the point of destroying a handgun?
One example I was given is when a minimum powder load is shifted in a case such as when the barrel is pointed down and then the gun is fired, the position or lay of the powder can have several flash points thereby increasing pressure. Is this common ?
A lot of key points have been made.
My consensus or 2 cents.
This is a razor blade issue. When you see factory "Reduced load ammo" this stuff is loaded, tested, over and over with known powders etc.
That means what powder are they using? is it fast or is it slow?
Is it temperature sensitive?
Barrel length Vs. Gas expansion time Vs. Bullet weight.
The bottom line is if you go to low, The bullet can and will become a cork. If that trapped gas cannot find an escape it will find the weakest point to vent.
I have seen over loads destroy guns.
I have seen under loads destroy guns.
I have seen Temp sensitive powders destroy guns.
If you go light work it Read the books! cross check manuals powder and bullet and primer!0 -
All this hearsay doesn't mean diddly. Can I get some thermodynamics data and calculations? [:D] I think we need do do some quantifying. [;)] 0 -
quote:Originally posted by shoff14
All this hearsay doesn't mean diddly. Can I get some thermodynamics data and calculations? [:D] I think we need do do some quantifying. [;)]
Lets start with your guns as as a bench mark.[:D]0 -
I would not recommend ground wood as a case filler. It is fairly heavy and will add to the mass of ejecta to be allowed for in loading. It will not burn under gun barrel conditions, it will blow out the barrel like it went in. It will be subject to packing and constriction in a bottleneck case.
Fillers I have heard of include Cream of Wheat, grits, shotshell plastic buffer, cotton, kapok, Dacron, toilet paper, cork, and caulk backer rod. I also every once in a while read of ringed chambers.
Therefore I do not load way outside the published data and I do not put non-gunpowder crap in my ammunition.0
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