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Detonation ?

torizustorizus Member Posts: 120 ✭✭
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 ?
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Comments

  • bpostbpost Member Posts: 31,002 ✭✭✭✭
    edited November -1
    From my study it is NOT common, it is theory, I don't think you can make it happen by trying too. My gut feeling is the issue has been double charged cases with Bullseye more than colliding pressure waves in the case. With modern Peizo strain gauges you would think they could eventually duplicate the phenomenon in the lab. To date that has not happened to my knowledge.

    I have seen chronograph results change in relation to powder position in rifle cases with lead bullets. I have not seen a velocity spike that indicated abnormal pressure.

    Recently the 125 grain bullet in a 357 mag and all 41 mag loads using Blue Dot were pulled from the books. I wonder if a inconsistent pressure spike was seen, causing the recall.

    I tend to use Unique for reduced loads in large pistol cases, I have never heard of that powder causing issues, real or imagined. My go-to powder for rifle cases and lead bullets is 2400 although 5744 might be better in some.......
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    I agree completely with bpost. When experts examine a destroyed gun, they can tell if true detonation took place versus a high-pressure metal failure. They haven't seen true detonation yet. Every example to date has been due to overcharging of powder.

    I spoke to Alliant's head ballistician about the Blue Dot issue, and all he was willing to tell me was that they saw "abnormal results" in the pressure curves in those two cartridges. He would not specify what that meant - clearly out of legal caution, for which I do not blame them.

    Powder position in the case can and does cause velocity variation, but I personally believe that you have to deliberately position the powder to create it. Normal handling and cycling of the gun between shots will evenly distribute the powder in the case -- unless you are in the habit of shooting at your toes. (If you are, the velocity won't matter at that range, LOL!)
    I may be a bit crazy - but I didn't drive myself.
  • torizustorizus Member Posts: 120 ✭✭
    edited November -1
    Thanks guys, I wasn't familiar with this occurrence as a beginner, and I primarily load light and stay at the manuals threshold. The issue came up in a conversation regarding .44 Secial loads in magnum cases.
    I'll sleep better knowing this phenomenon is a possibility but not probable. Although it is something to put in my FYI and best practices box.
    I went head first into this hobby and bought just about any dang thing someone makes for reloading not to mention all the guns, the inspiration to try reloading came from this forum but the interesing and fun part that sustains it is knowing I have access to the pros knowledge when I need it...thanks again.
  • Tailgunner1954Tailgunner1954 Member Posts: 7,815
    edited November -1
    RR and bp
    explain this one, and the load data given is "as best remembered"
    Blown86Win2.jpg
    There were 9 empty cases on the table, and 9 holes in the target when the 10th round was fired. Shooter (my gunsmith) lost parts of several fingers.
    He feels that this one may have been due to metal fatigue, but also holds that a "dual ignition" can also occur. IE the bullet starts to move under pressure, the increased volume causes the pressure to drop allowing the bullet to stop, and than when the pressure builds again it's dealing with a "obstructed barrel" situation (pressure exceeds metal strength before the bullet starts moving again).
    A few years back there was some imported (Chilean?) 50BMG ammo that blew up several M-2's. He witnessed one "misfire" where the operator was fast enough on the charging handle that when the gun didn't fire, he ejected the case at which time the powder flamed off (bullet was still in the throat). Not exactly the same as a "light load" but a similar/related cause.
    BTW the "proper name" is S.E.E. "Secondary Explosive Effect" (note EFFECT, IE like an explosion, not a actual explosion)

    IIRC, SEE HAS been duplicated in lab testing, and it's a somewhat random thing IE: something like 1 in 1000 tries
  • bpostbpost Member Posts: 31,002 ✭✭✭✭
    edited November -1
    The Manual is the key to safe reloading. When you feel more confident in your loading do not be afraid to step up, slowly and carefully to max charges. Many guns and many calibers tend to shoot best up near max loads.
  • bpostbpost Member Posts: 31,002 ✭✭✭✭
    edited November -1
    quote:Originally posted by Tailgunner1954
    RR and bp
    explain this one, and the load data given is "as best remembered"
    Blown86Win2.jpg
    There were 9 empty cases on the table, and 9 holes in the target when the 10th round was fired. Shooter (my gunsmith) lost parts of several fingers.
    He feels that this one may have been due to metal fatigue, but also holds that a "dual ignition" can also occur. IE the bullet starts to move under pressure, the increased volume causes the pressure to drop allowing the bullet to stop, and than when the pressure builds again it's dealing with a "obstructed barrel" situation (pressure exceeds metal strength before the bullet starts moving again).
    A few years back there was some imported (Chilean?) 50BMG ammo that blew up several M-2's. He witnessed one "misfire" where the operator was fast enough on the charging handle that when the gun didn't fire, he ejected the case at which time the powder flamed off (bullet was still in the throat). Not exactly the same as a "light load" but a similar/related cause.
    BTW the "proper name" is S.E.E. "Secondary Explosive Effect" (note EFFECT, IE like an explosion, not a actual explosion)

    IIRC, SEE HAS been duplicated in lab testing, and it's a somewhat random thing IE: something like 1 in 1000 tries


    Wow, If I had to hazard a guess it would be a failure of the receiver at the thin spot where the feed tube passes under the barrel, it is a known weakness on lever guns. Many have failed at that spot with similar results. It may have been cracked for years without being visible, the cracks are hard to detect unless the feed tube is removed and the metal is fluxed in that area. He just happened to pull the rigger when the crack decided to let go, destroying the gun, and unfortunately injuring your friend.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    SEE is indeed the correct term, and it can be duplicated. It is usually associated with much-reduced loads of very slow powders like 4831 in rifles and H110 in handguns. Here's a photo of a reduced charge of H110 in which all the deterrent coating has been burned off by the primer flash, but the powder did not ignite. If it had, it would have had the effect of a hang fire, followed by a severe over-pressure as the undeterred powder burned at a greatly increased burn rate.

    hangfire.jpg

    Here's a lab test of a multiple charge of Bullseye being fired.

    blowup.jpg
    I may be a bit crazy - but I didn't drive myself.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    There is one plausible explanation for burst barrels when using light loads that has not been addressed here. In a cartridge that has a limited amount of free space, the ignition of the powder column starts at the base (near the ctg head) and progresses toward the head at the base of the projectile. The initial ignition by the primer compresses the powder and allows the flame front to move through the powder column in a controlled manner

    In a cartridge that has an excessive amount of free space, (light load without any filler) the primer can spread and separate the individual grains of propellant and allow them to ignite simultaneously. This circumvents the "progressive" properties of the propellant and causes a very high pressure spike of short duration.
    This is far less likely to happen in pistol ctgs.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    Well, that's certainly an imaginable sequence, but nobody has ever seen or recorded exactly what happens in a cartridge (and maybe never will) so while plausible, we don't know for sure. BTW, I call that scenario the "leafblower effect" and is the main reason why I doubt the theory that powder position has a significant effect in handgun rounds.

    But I have to quibble about your use of "progressive burning." Your description is not at all what a propellant designer would use. Rather, progressive burning means that an individual kernel of powder exposes more and more surface area as it burns, thus burning progressively faster until it is consumed. Extruded kernels with a deterrent coating on the outer surface and a microscopic hole through the center burn progressively because they burn from the center outwards. Powder that burns from the outside in (flake propellants are one example) burn REgressively because they expose less surface area over time. Powders designed to burn both ways are neutral burners.
    I may be a bit crazy - but I didn't drive myself.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    Rocky,
    What you say with regard to individual grains (flakes, spheres etc)being progressive burning due to increased surface area is true. But the progressive nature of the powder column as a whole is determined by the rate at which the flame front passes from ignition point to the last grain of powder. With small charges of powder in a more open environment, it is possible to ignite ALL of the charge at once. Ergo...BANG !
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    That may or may not be true, but with small charges of powder there is also not enough propellant available to generate sufficient gas to cause a "bang." Just not enough energy content present for it.
    I may be a bit crazy - but I didn't drive myself.
  • perry shooterperry shooter Member Posts: 17,390
    edited November -1
    Hello RR thanks for picture . I was using an inertia bullet puller to pull some 230 grain Military ball bullets to run a test. You know this stuff has black goo to seal the case mouth and you need to really pound the puller to get them to come out of the case on about the 8th round I really smacked the puller and got a big Poof and the bullet was seated back into the case mouth about 1/64 inch the inside of the puller was Bright Yellow and when I remove bullet from case mouth all the powder was gone. primer was still intact and live. I don't have a clue what happened but needless to say it got my attention and I have never tried to pull a military ball bullet after that. The bullet on case 1-7 would sometime wedge in the tapered front of inside of bullet puller . I surmised enough friction or pressure between bullet #8 and cone at front of inside of puller started the powder burning. but lack of pressure "THANKFULLY" it did not go Kaboom.
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    in rifles, it is caused by a light load of powder being ignited all at once rather than buring from rear to front. Picture a case layed down in the chamber, which allows the light charge of powder to lay at the bottom of the case, and it is under the flash hole's axis, then the flash can jump across the entire charge, igniting it all. Thus, the pressure curve spikes to above maximum in a very short time, and in reality, the bullet just can't get out of the way fast enough. I have not nor will I experiment with light loads or powders too fast for a particular case's volume. when doing this, it is not a case of if,...but more a case of "when"
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    If that's true, how do we explain the many factory and military loads which you can shake and hear that the case is less than full of powder? None of them "detonate". Only handloads do.
    I may be a bit crazy - but I didn't drive myself.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    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)
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    I still can't see it. In anything but a compressed load, all or almost all of the powder ignites at the same time. The mental image of "burning from rear to front" like a cigar is simply fallacious. The explosion of the primer, with the attendant abrupt rise in temperature and pressure, initiates ignition in all the powder except for kernels in contact with case or bullet metal. (That's not my theory. That's what a genuine rocket propulsion engineer and cartridge designer tells me.)

    Then there's the handgun aspect. Many handgun loads use only a pinch of very fast powder. The "flash across and light everything" model happens with nearly every shot from a handgun, yet no detonations seem to happen there with factory ammo. Handloads, yes; but as I pointed out, those invariably turn out to be double-charged or worse.
    I may be a bit crazy - but I didn't drive myself.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    Rocky, I can tell you from my time at LLL that ultra high speed photography reveals that even in the most volatile of explosives, ignition starts at a point and progresses through the mass. The time element in question is extremely short and it may seem like the explosive/propellant ignites as a mass, but it doesn't. The only difference between an explosive and a propellant is the velocity of the burn.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    I'll grant you there is a speed of propagation - that's what obviates anything we're discussing as a true detonation: it happens far too slowly to be an explosion. But the primer blast IS an explosion, and its shock and heat effects propagate through the powder so many times faster than the burn speed of the propellant itself that I feel justified in using the unscientific phrase "ignites all at once."

    I'll go with what the real expert tells me, guys. The discussion is interesting but the real science of it is probably out of all our depths.
    I may be a bit crazy - but I didn't drive myself.
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    powder columns burn from rear to front, Or bottom to top if it is pointed upwards. Any factory or military round can be shaken and the powder can be heard inside, however, the load density (as stated) is at least 70%, which means that when layed down (or in the chamber) the load still comes to 7/10's of the way up the case, which puts it well above the 1/2 way point of the flash hole.

    detonation occurs when the load density is far below that 1/2 way point, and the entire charge can be ignited as the flame jumps across it unimpeded.

    that is why many of the catastrophic failurs pictured on the net, are from light loads and often people being cheap and trying to figure out how to make fast burning powders work in cases that are far larger than the intended cases for the faster powders.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    That's vivid mental image, but completely divorced from reality. Do you really imagine that something as light and often as fluffy as gunpowder just sits there in the midst of a literal explosion? Uhhh....no.

    As I said above, unless the case is 100% full, the primer explosion blasts all the powder around, driving flame, hot particles and highly compressed (hot) trapped air into every interstice between kernels. Almost all of it is exposed to temperatures above ignition temp on nearly every shot, and nearly all of it gets ignited every time. Only in long and thin cartridges will there be any differential between the rear and front of the powder column, and that is created by compression of the powder into a nearly solid plug.

    The Secondary Explosion Effect is real, but it is due to other, much more complex causes than imaginary "primer flashover."
    I may be a bit crazy - but I didn't drive myself.
  • torizustorizus Member Posts: 120 ✭✭
    edited November -1
    Wow..a lot of good solid points here and it sounds like handloads may be more likely to experience a "SEE" as opposed to factory ammo.
    Might we be looking at a Crimp factor here ? Was it used in any of the known incidents ? If so,to what degree ?
    Just asking..as I read the responses, I find my limite
  • Tailgunner1954Tailgunner1954 Member Posts: 7,815
    edited November -1
    Torizus
    In the history of SEE, it is most often seen when (and it was a fad in the 60's) trying to make light recoiling plinking loads for the big boomers. Example: 30 carbine level recoil in a 300 RUM case.
    Above someone mentioned a 70% fill threshold, more often it was seen when the powder fill level was in the 20% (or lower) range.
    Manuals offer you a starting point, and that level is well above what will cause SEE (there are some powders that explicitly recommend that you NEVER go below the manuals starting level)
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    gunpowder is not fluffy, it lays just like gravel in a driveway. There is no such thing as making gunpowder fluffy and having it sit above the horizontle flash axis when it is a light load.

    as far as blasting flame into every millimeter of the case, and encompasing the powder 360*, that is not how it happens. The "burn rate" of powder is the exact caveat to that theory. Powders are listed by "burn rate", which means that applying any average tested brisance (the amount and lenght of time a flame comes out of the flash hole), the powder will burn and build pressure at the specified rate, in a given case capacity. By using powders far too fast for that given capacity, you change the pressure curve. A fast powder in a case too large will build pressure more rapidly than the surrounding metal can handle. When experimenting with light loads, especially in powders too fast for the case capacity, you are looking for trouble, or worse.

    also, the only way powder and fire become compressed is the ignition of the powder charge, while the bullet remains almost still. The milliseconds during ignition create pressure as the load ignites, and the bullet starts to move. The majority of powder, burns in the barrel, not it the case. If it took place in the case, the cases would burn through in several firings. Brass is far less dense than steel.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    JustC, my friend, just about everything you said in that post is wrong. You are perfectly free to believe those ideas, but I'm also free to disbelieve them. Unfortunately, there is no way for either of us to prove our ideas, because they haven't yet (and may never) find a way to get a camera inside the case and record what happens.

    There isn't space to counter all your incorrect points, so I'll just disprove the most comical of them. Powder lays like gravel? Puff some air at gravel, and then puff at some powder. The concept that powder just lays there while a small explosion blasts at it is ludicrous.

    Unless someone has a cogent question for me, I'm finished with this thread. The positions have gotten implacable and unresolvable.
    I may be a bit crazy - but I didn't drive myself.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    well Rocky, you're sure wrong there. Not only is it possible to see what takes place in a cartridge case at the time of firing, it happens as a step in production of large caliber munitions. Xray is used to expose the film used in ultra high speed photography. Ya can watch it all !
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    quote:Originally posted by XXCross

    well Rocky, you're sure wrong there. Not only is it possible to see what takes place in a cartridge case at the time of firing, it happens as a step in production of large caliber munitions. Xray is used to expose the film used in ultra high speed photography. Ya can watch it all !


    AND, the only way powder is puffed around, is if the load density is too low, leaving room for the powder to be blown around. When a correct load desnity is used, there isn't enough space for the powder to be "blown around" as there is maybe some 10-20% capacity left unfilled.

    maybe this explains why there has never been a detonation in full or close to full cases[?] it only happens on light loads or light loads of powder too fast for that case size, it never happens when correct load density is used with appropriate burn rates. This is EXACTLY why the lawyers make the reloading manuals have statements about not going below the recommended charges, this way, when you blow the gun up playing with undercharged cases, they have no liability because they told you not to.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    That's interesting about the X-ray photography, XX Cross. Thanks. Still, there are important processes that don't "scale" down from large munitions to small arms cartridges, which means we can't say the two behave alike.

    JustC, you brought up the supposed "flashover" with small charges, and I maintain that such a thing is impossible. In fact, what I call the "leafblower effect" would be MORE likely to over-ignite a small charge than a flashover where only the top of the powder surface is exposed. Yet, in 99.999% of times, such loads function normally. If small charges cause SEE events, they are darn poor at it.

    BTW, on another website a guy reports that he blew up a Mauser in 6.5 Swede - with a nearly full charge of 4064. He weighed every charge TWICE and visually observed the powder level in every case before seating a bullet. So don't say a SEE has never happened with a full charge of slow powder.

    Both these things reinforce what I've been saying all along: that SEE events do happen, but the popular "explanations" of what cause them are probably wrong. Something causes them, but we haven't yet learned what.
    I may be a bit crazy - but I didn't drive myself.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    Well rocky, as YOU said, nothing is impossible. If someone blows up a $200 rifle, few people will care. If someone blows up an $800K artillery piece or a $2.7M navel gun (over the magazine) that gets a real * chewing. Small arms ammo is manufactured to work under a set of conditions...it does so quite well. It is only when someone starts stirring the pot do things get dicey. I'm sure if someone just HAD to know the "why and how" of it all, they could conduct the same type of tests and observations as the ord. industry does...bring a BIG check book.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    Indeed it would take a big checkbook. Here's a brief note from a genuine expert who was doing that very thing regarding 5" naval guns. http://findarticles.com/p/articles/mi_m0BTT/is_170_28/ai_n6040281/

    And here's a magazine writeup quoting an unnamed powder company ballistic lab. Both seem to confirm my major claims. http://africanxmag.com/secondary_explosion_effect.htm
    I may be a bit crazy - but I didn't drive myself.
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    He had another thing to add, and that was that S.E.E. does not just occur with "slow" powders, but can and does occur with fast powders as well. His experience has been with "Cowboy Action Shooters", who are loading small charges of fast powder.

    hence my point

    Another thing that was causing guns to blow up was in those large cases with light charges, they could be "double-charged". There is enough room to get two charges in the case and not really know it. So, when seating the bullet, no undue problems are encountered in bullet seating. But when fired, the gun comes apart

    again, my point. Those who experiment with powders too fast for the case capacity, are asking for SEE. There is a clear cut reason that powders are listed by burn rate. They are meant for specific case volumes coupled with a particular projectile weight range. When using unsuitable powders, they are in the danger zone. If they double charge a bottleneck rifle case, with pistol powder, I would bet they couldn't look into the case and see the difference. Pistol powder loads would be around 10grs if double charged, and when the case will hold 80grs, they are wayyyy off into the playground.

    He had another thing to add, and that was that S.E.E. does not just occur with "slow" powders, but can and does occur with fast powders as well. His experience has been with "Cowboy Action Shooters", who are loading small charges of fast powder

    the article also doesn't state that this happens with full case loads of slow powder, a very important peice of info. I have run H870 and even 50BMG powders in a 300RUM. However I was using heavy 200+ gr pills and the case was FULL. What I got was reduced muzzle velocity and dirty cases, which is a sign of LOW pressure. Low pressure doesn't blow up guns, high pressure does. Now a light load of slow powder, with a spark jumping across it, I could see SEE possibly happening.

    also remember, powder companies use what they call "test guns". These are large actions with huge barrels. The amount it takes to blow up a test gun as opposed to a hunting rifle, IMHO will be different. They really should include chamber pressure data with their load data, that would be a big help for the reloader. They have strain guages that they use in testing, so they should include the avergae chamber pressure with the load data. I for one, would appreciate that as a reloader. Also keep in mind, their barrels are far more quality that the factory pencil barrel.

    not to say it is explained in simple terms, but eh large majority of SEE I have seen on the net, and posted by the owners over the years, are from someone messing with small charges of fast powders. Stick to the load manual suggestions. I don't experiment outside the manual, unless it is with heavy charges of slow powders pushing heavy bullets.

    Terry is a very inteligent person as I have read his posts on another site for many years. I am going by the examples posted on various sites over the years, and the comments from the person who actually blew the gun up.
  • BergtrefferBergtreffer Member Posts: 629 ✭✭✭✭
    edited November -1
    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.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    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 ?
  • BergtrefferBergtreffer Member Posts: 629 ✭✭✭✭
    edited November -1
    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.
  • sandwarriorsandwarrior Member Posts: 5,599
    edited November -1
    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.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    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.
    I may be a bit crazy - but I didn't drive myself.
  • BergtrefferBergtreffer Member Posts: 629 ✭✭✭✭
    edited November -1
    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.
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    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.
  • XXCrossXXCross Member Posts: 1,306 ✭✭✭
    edited November -1
    I think I'll just sit this one out.
  • sandwarriorsandwarrior Member Posts: 5,599
    edited November -1
    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.
  • Rocky RaabRocky Raab Member Posts: 10,891 ✭✭✭✭
    edited November -1
    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:

    hangfire.jpg
    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:

    blowup.jpg
    I may be a bit crazy - but I didn't drive myself.
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