Secondary Explosion Effect (SEE)

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303PV posted this 20 May 2021

 A search has shown that this subject has been discussed before, but I would like to get some recent opinions.   I have been reloading cast bullets since 1975. I read the first edition of the Lyman Cast bullet handbook and I started from there. I read the original article about Cast bullet loads in military rifles published by C.E Harris that I liked very much because of the systematic approach.  Since then I have shot many .. many thousands of cast bullets. Recently I have seen a lot of discussions on German reloader forums that the powder volume should not be lower than 80%. Vihtavuori mentions in their 2021 reloading guide (german version)." Risk of detonation through reduced loads etc" Quick Load also warns for a SEE. Are these warnings, caused by product liability concerns? More discussions on the internet?  A mystery factor created by infallible people who won't admit that they could have put a double charge in the case? I have only used fast-burning pistol and shotgun powders or the fast rifle powders like N110.

Please help to put my mind at ease. 

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RicinYakima posted this 10 June 2021

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John Alexander posted this 14 June 2021

I guess I didn't state my thoughts clearly enough in the last post.

I think this thread has degenerated into bickering and complaining about  each other, with occasional car pictures but little or no progress.

All future posts will be deleted.

John

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Wheel Weights posted this 23 May 2021

IMHO, there are too many choices in powder to take the most remote chance.

 

Just like the old rule of: "Always use a powder and load that will overflow the case with a double charge."

 

KISS is always my choice when available.

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Larry Gibson posted this 24 May 2021

The real cause of SEE was indeed found and proven 40 +/- years ago with the advent of transducer and strain gauge pressure measuring.  All of the old theories regarding detonation, waves, etc. have been disproven.  What occurs is essentially as wineman states in his post; the bullet, given certain circumstances becomes a bore Obstruction.  Knowing the circumstances required it it is easy enough to reproduce.  being able to measure pressures and observe the time/pressure curve I have done so several times but have stopped just before the SEE probably would have occurred.   It is easy to produce and the catastrophic results are very predictable.  

BTW; not loading below 80% load density was an incorrect solution.  An SEE can result from 100% load density or even with a compressed load.  SEE is also not a phenomenon of just slow burning powders in over bore cartridges. 

LMG 

Concealment is not cover.........

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Wineman posted this 12 June 2021

Here is the article:

Handloader SEE

Dave

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MP1886 posted this 12 June 2021

It doesn't matter that a bore obstruction is too easy to comprehend.  That's what happened in the article in my opinion and others including the author.  There are many kinds of bore obstructions you know, from stuck bullets to stuck wads to dirt plug in the muzzle to putting a 20 gauge shotshell in a 12 gauge shotgun to Kapok filler the list goes on.   I think SEE became a mystery because those that had it happen probably felt they did nothing wrong. I think it was something they worked up the loads on a pressure barrel all to specs and all the loads looked just great, then they go to the actual rifle and boom.  No mystery to me.

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beagle6 posted this 21 May 2021

The first I ever heard of SEE was a report by Jack OConnor when he was shooting editor for Outdoor Life Magazine. He was loading 60 grains of 4831 for a 270, if memory serves, and had his powder measure set for 30 grains. A double throw and he had his load. Evidently he didn't throw the second charge on one cartridge. I don't recall the damage but it shook Jack up. He reported it to the NRA who tried to duplicate the event without success. To my knowledge, no one has either. Seems to happen with stick powder slower than 4895 and 4064 and certain ball powders.

beagle6

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Wineman posted this 22 May 2021

Somewhere in my archives is the work done on Swede Mauser's in 6.5x55 and SEE. If I find it I will post but the Cliff-Notes are this:

The primer fires and the ignition and gas production of the powder starts. When sufficient pressure develops, the bullet is pushed from the case into the rifling of the barrel. In the Swede Mausers, that had issues there was considerable erosion at the throat and and the moving bullet (long and with a heavy jacket) would momentarily "pause" at this point. Rather than proceeding smoothly down the barrel it had become a bore obstruction. Since the pressure has nowhere to go, the weakest part, (cartridge case) now ruptures. These were with normal ammunition. A lot can happen in a short time.

Dave

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GP Idaho posted this 24 May 2021

Talking to some about SEE's is akin to telling them you believe in Bigfoot. Personally, I'm just not taking that chance. Ninety % of my rifle loads are cast and if I do load jacketed bullets they are not reduced loads as I have no need of such.  In my cast bullets, most of the cases are charged with powders fast enough to put any worries of such an explosion to rest in my mind. It seems that the last article I read on SEE's concerned very slow military surplus powder loaded way below case capacity without a kicker charge. No danger of me going there either. Now, on the very fast powders, Bullseye, TiteGroup and the like I have no worries using VERY small charges.  If you're confident in your loading practice, load away. I'm just not confident in small charges of slow powder so I don't load them. Gp

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Wineman posted this 29 May 2021

However you get a bore obstruction it is never a good thing. Remember the gun does not "blow up". The weakest part of the rifle, the cartridge case, ruptures and the high pressure gas has a much larger surface area to press against and much weaker parts to restrain the pressure. The chamber area is intact but magazines, floor plates, stocks, bolt faces and firing pin holes all take forces they were not designed for. It has been over 130 years since smokeless propellants were developed. When the company that produces the propellant, says "this is dangerous" don't say "hey, hold my beer and watch this". Be careful out there and have fun.

Dave

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Wheel Weights posted this 06 June 2021

"heard about", "read about","seem to recall"," could not duplicate", "try to find story"

 

Notice the common thread ? Even Bigfoot stories have pictures and videos !

 

 

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John Alexander posted this 13 June 2021

I thnk Ric is right.  I can't see that we are really getting anywhere  with the SEE discussion. We seem to got to the bicckering stage. If some want to have a discussion about  hot rods please start one.  I don't intend to delete this thread unless the discussion continues. Can we just let it drop.

John

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99 Strajght posted this 20 May 2021

Yes it does exist. I have had it happen and I can repeat it. I have never had it with cast and have been shooting cast for 60 years. Follow these rules. Stay with the faster powers. Be careful of slow powders and less than 3/4 a case full. Seat your bullets to almost touch the rifling or more. Handloader has a lot of good articles on SEE.

Glenn  

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RicinYakima posted this 20 May 2021

Norma, the powder folks, did a lot of research and published their findings in the 1970's. Think the results were published in their booklet called "The Gun-bug's Guide". 

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Wheel Weights posted this 21 May 2021

It may or may not be true BUT why take the chance ? So many powders work fine why bother ?

 

Harry Pope didn't have 4831 and he did okay.

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Squid Boy posted this 22 May 2021

I think one of the best decertations on SEE was in a Wolfe publication called "Firearms Pressure Factors". There is a lot of detail about testing conducted by Col. G.O. Ashley and Lloyd Brownell. Both sides seem to make viable arguments about weather this phenomenon is a real problem or not. I have seen some very interesting pressure spikes that seem to occur after the bullet has left the muzzle when using a Pressure Trace system. I don't have a good explanation for them. I believe there are examples posted at the Shooting Software site. I am still not sure about it one way or the other although I do watch my load densities. Usually very divided opinions on this. Thanks, Squid Boy

"Squid Pro Quo"

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RicinYakima posted this 23 May 2021

Yep that is the Norma study I remember. Also it didn't happen with a clean barrel in their testing, but only after it had been fired. It appeared that carbon in the throat added to resistance of bullet engraving. 

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RicinYakima posted this 23 May 2021

I have no idea who Nick Harvey is but other than good grammar, it is just opinion. Nothing wrong with that, just not convincing. Bob Shell appears much more convincing and has done some things most of us have done over the years.

Thanks for the links WW.

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Larry Gibson posted this 25 May 2021

 Squid Boy

I have been present when two SEEs occurred which destroyed both rifles.  I also have investigated several others being able to inspect the destroyed rifle and question the shooter/reloader to determine how the ammo was loaded and what occurred during the shooting.  I also have duplicated the test pressure results and like the technicians conducting that test backed off when the pressure got into or above proof load pressures.  I do not fancy destroying one of my rifles to prove a point to you. 

However, I am more than willing to destroy several of your rifles.  If you would send a 6.5x55, 25-06 or any of the short magnum of 270 or less caliber rifles I will gladly show you how its done and provide complete data of the loads and pressure traces.  You or anyone else is free to attend and witness.  Would still cost me 3 or more strain gauges plus the components but I'll go that if you will provide the rifles?

LMG

Concealment is not cover.........

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