Has anyone here ever experienced a "low volume explosion" from using a below "minimum" charge weight in a reloaded cartridge?

I keep seeing this in print but have never seen anything written by anyone who has actually seen it or experienced it.

I've read about it too, and believed it, so I haven't experiienced it. I don't load light powder charges because of what might happen..???

Wink

You'll have to go back to some of the publications of the 20th Century. HANDLOADER magazine had a couple of articles about it (S.E.E., Secondary Explosion Effect) in the late 60s. P. O. Ackley did some experiments and you will find discussions in some of his books.

I don't think anyone was able to duplicate it on demand but there's no doubt that it does exist.

Ray

9 rounds fired, 9 holes in the target, this happened on round # 10.



Is that the kind of thing you had in mind?

detonation can happen with small charges of slow burning powder. not ofter but can happen. fairly well documented

I've read once that slow ball powders are more prone to do it.

I blew 2 primers with a slighty reduced load of AA2495 in a 7.65 Mauser. I think poor ignition due to the bolt having a lot of cosmoline in it caused the problem.

I had asked this same question , on this forum IIRC,a couple of years ago and someone mentioned a laboratory duplication of the problem.Can't remember the source but it has been proven.

I had a primer pocket expand and the bolt had to be beat open with a mallet on my 6.5 Swede with 46 gr's of 4831, listed as the most accurate load. My friend had the same thing happen to him with the same load. The guns were not damaged. Seems as if the throat is so long on these guns that the bullet can move foreward before the powder gets burning good, the bullet stops at the rifling for a millisecond and the powder pressure hits it.
I switched to Varget and worked up a load that will hold 1/2" at 100 yd's with no more worries. NEVER reduce loads with slow powders below starting loads. For guns with long throats, load to max, use long bullets to reach the rifling or use a faster powder.

brfshooter,
The two blown primers I mentioned above occurred with a load that was extrapolated/interpolated 2 gains lower than AA data. At the time I loaded the 7.65 rounds AA did not have data for the 7.65 Mauser. I referenced their data from similar cartridges and played it safe...I thought. After cleaning the bolt of the excess cosmoline I eventually increased the load 3 grains without any problems.
They advertise AA2495 as a replacement for the 4895s. After that little episode I decided to stick with IMR or H4895 for that burn rate.
They can keep their AA2495.

quote:

I don't think anyone was able to duplicate it on demand but there's no doubt that it does exist.

Actually, they have been able to duplicate it in the laboratory. I forget exactly where I read it, but IIRC, it may have been a short squib in either RIFLE ot HANDLOADER, probably the latter. it is easiest to duplicate in the .243 Win. and 7MM Rem. Mag as I recall.
S.E.E. (Secondary Explosion Effect) may be the most popular name for the phenomenon, but P.E.P. (Pressure Excursion Phenomenon) and D.D.T. (Deflagration to Detonation Transition) also describe the problem as well.
There is an article by a Roy Smith who had problems along this line while loading for a rifle in .243. I forget if it was in HANDLOADER or RIFLE as it was quite a few years ago. it's too bad those two magazines stopped taking articles from us dirty unwashed, thanks Dave Scovil, as the few article that this Roy Smith did were quite interesting, even if it was opinionated as hell. IIRC, both Jack O'Connor and Elmer Keith was also opinionated as hell.
I guess jacking up the bottom line is more important than giving out truly serious information and feeding us pablum on the latest hot shit fire breathing super magnums. After all, even field mice now wear kevlar.
Paul B.

I'm not saying these low volume explosions can't happen, but they should be reproducable. I mean, charge weight/volume, case volume, projectile weight, bore diameter, powder position, primers, temperature, and so on, should all be reproducable and testable.
How much more catastophic could a low charge weight be compared to, say, incorrect projectile diameter or weight? People often speculate how a blow-up was caused by a low charge weight, but how can they be sure? Why don't so called "cat-sneeze" loads in big bores result in blow-ups? What about using minimun/start loads with the slowest powders for the heaviest projectiles with the lightest bullets? These loads would be way under the recommended loads by the powder companies.

Just wondering...Albatross.

Let sleeping Dogs Lie !.

I personally have never had it happen , but indeed have been on a range when it happened to someone else .

As a matter of fact I was one of 3 people who caught shrapnel . I also was one of the people who took a few of the shooters rounds home and opened them up .

What this person was thinking was beyond my understanding .

He was firing a magnum 300 Winchester key word WAS !!. Please remember that !.

For what ever reason he had reduced loads of a Shotgun powder Blue you know who and small volume in the cases . Magnum primers .

When the cartridge was lying down powder would not fill primer pocket cavity fully .When the firing pin detonated the primer This caused a Flash over and spiked pressure sky high .

It would have been ok if he had used a dacron wad to keep all the powder at the primers end .

Shoot Straight Know Your Target . ...

quote:

Originally posted by Albatross:
I'm not saying these low volume explosions can't happen, but they should be reproducable. I mean, charge weight/volume, case volume, projectile weight, bore diameter, powder position, primers, temperature, and so on, should all be reproducable and testable.
How much more catastophic could a low charge weight be compared to, say, incorrect projectile diameter or weight? People often speculate how a blow-up was caused by a low charge weight, but how can they be sure? Why don't so called "cat-sneeze" loads in big bores result in blow-ups? What about using minimun/start loads with the slowest powders for the heaviest projectiles with the lightest bullets? These loads would be way under the recommended loads by the powder companies.

Just wondering...Albatross.

I can give you the recipe if you want to reproduce it.
You just have to report back with the results.

Bad idea to start your own testing lab at home unless you have the equipment and technical expertise. Any bolt gun that would blow up from under/over charging belongs in the dumpster. Too many of these crap boxes are floating around out there with minimal to no safety factors engineered into them. Many were never designed for modern loads, and many are just tired. Kills me that I see so many people idolizing these old clunkers which no doubt have dubious metalurgy and likely fatigue. If it looks like a museum piece hang ot on the wall and buy something new.

quote:

Originally posted by Macifej:
Any bolt gun that would blow up from under/over charging belongs in the dumpster.

So, what bolt gun would you suggest using, that will handle a excursion into the 90-125,000psi range?
IOW have someone put a piece of plexiglass into your naval so that you can see where your walking.

Anything not made from potmetal (investment cast parts) or in the early 20th century (primitive metalurgy and fatigued). Try a Weatherby MK V, a Heym SR30, a Blaser R93 and most other quality bolt guns with any reasonable safety factor. I can make you one that will do 300,000 PSI if you have the $$$$$$$. At 300k psi my biggest concern would be the copper plated bore after round one and gas diversion from the liquified cartridge case.

Obviously, the case of the exploding pot cast blacksmith model Winchester in exhibit A would have come apart with any kind of reasonable pressure. 16 grains of any powder is a joke.

I bet you know that the big Weatherby's, Lapuas, and most medium bore military rounds operate at mean chamber pressures of 65 - 70k at average ambient temps. Black powder cartridge guns operate in the 10-15k range!

quote:

Originally posted by Cheechako:
Wink

You'll have to go back to some of the publications of the 20th Century. HANDLOADER magazine had a couple of articles about it (S.E.E., Secondary Explosion Effect) in the late 60s. P. O. Ackley did some experiments and you will find discussions in some of his books.

I don't think anyone was able to duplicate it on demand but there's no doubt that it does exist.

Ray

Yes, it has happened. The culprit seems to be using a reduced charge of super-slow powder such as AA 8700 in a large-capacity, small-bore cartridge like a .240 Gibbs, 25/'06, etc. But as mentioned, the phenomenon cannot be reproduced at will, it is a seemingly random occurrence.