gwpercle
Member
The press has little to do with safety ... it's the PPH ...
... Person Pulling the Handle !
Gary
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Strange Kaboom
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... Person Pulling the Handle !
Gary
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The detonation mentioned in this thread has been related to small charges in large cases used in fire-forming certain rifle cartridges. 2400 is not a fast powder for pistol. But it is for rifles. So when they say "small charges of fast powder in large cases" they are talking about 2400 and 45/70 cases. That is a whole different world than anything we're dealing with. This is an issue in that endeavour only. It just doesn't happen in handgun cartridges but that statement has been extrapolated to handguns. There's no documented evidence that it occurs anywhere else than mentioned in that article.
They used to blame Model 14 kabooms on detonation because there were so many. But it was a very popular revolver. The reality is a double charge of Bullseye will blow your gun up. This theory was investigated six ways from Sunday by powder/firearm manufacturers and they could find no reason why it should happen and they could not duplicate the event. At this point it's been written off in my mind until somebody comes up with some hard evidence it occurs in handgun cartridges.
They used to blame Model 14 kabooms on detonation because there were so many. But it was a very popular revolver. The reality is a double charge of Bullseye will blow your gun up. This theory was investigated six ways from Sunday by powder/firearm manufacturers and they could find no reason why it should happen and they could not duplicate the event. At this point it's been written off in my mind until somebody comes up with some hard evidence it occurs in handgun cartridges.
LoboGunLeather
US Veteran
You are correct that the cylinder stop notch is offset between chambers. What I was referring to is the extremely thin steel wall remaining around the cylinder circumference as well as the very thin chamber wall remaining between the chambers in the 5-shot J-frames chambered in either .38 Special or .357 magnum. My question raised the issue of S&W's decades-long policy of limiting the J-frames to .38 Special standard pressure ammo (non +P), followed by the change to rating for +P and then the introduction of the same design platform chambered for .357 magnum.
.38 Special +P ammo is regularly rated at about 10% greater chamber pressures than standard pressure ammo, and .357 magnum ammo is rated at about double the working chamber pressures of .38 Special standard velocity ammo.
I would like to again stress my comments in my first post to the effect that I am not a metallurgist, I am not a professional engineer, and I am offering only speculation without accusation or conclusions.
Speaking only for myself, I have owned several J-frame S&W revolvers over the past half-century, and I have always limited their use to standard pressure .38 Special ammo. When I feel the need for .357 magnum performance I rely on medium and large frame revolvers for two reasons: (1) greater margin of safety, (2) extreme recoil of magnum ammo in the light-weight J-frames. That is my position, not something I wish to force on anyone else.
Best regards.
crankyoldlady
Member
The author addresses the possible detonation of light .38 Spl loads in a .357 Mag case...
(Comment on gun blowing up from reader. Date: 9-26-2007)
HELLO MR. SMITH
I was reading your site, very nice I must say and full of good info, and came across something in you “FAQ’s: And Answers from my e-mail pages (1-14) 1996” section. Here you said it was ok to use 38 spl loads in a 357. I thought I would share with you something that happened to a friend of mine while I was standing next to him on the firing line.
He had new Star progressive reloading press. He wanted to use this fine contraption but didn’t want to load for 357 so as to reduce recoil. He had been using 38 spl light loads. So he used this same loading in the 357 brass. I was standing next to him and heard a strange sounding report of the pistol. And his bullet strike was about four feet in front of us in the dirt. He is a very good shooter and I wondered why he had hit the dirt. I turned to look at him. His face was as white as a sheet. The top strap of his pistol was gone and the frame was bent so that the barrel was pointing at the ground in front of his. His 357 had detonated!
Some ballistic labs claim this can’t happen. Well I’m here to tell you that it can and does. We jawed about this for a long time and the only thing that came up that made any sense to me was this theory. With the light 38 spl load in the 357 case there was not enough powder to fill the case half full. This caused it to be spread across the side of the case while in the chamber and below the flash hole of the primer. When the primer fired flame from the primer ignited both ends of the powder. This caused two flame fronts inside the case. When they met in the middle of the case the pressure went way up and destroyed the pistol. It was put forth that he had accidentally thrown a double charge. But with the star reloading press this is not possible. It is possible to throw a no charge or a light charge if the powder measure is clogged but not a double charge.
I though I would share this with you so you can warn others about using light 38 spl loads in the 357 brass.
Thank you for your time
Joseph Murphy
(MY REPLY TO THIS EMAIL)
Yes, I certainly can believe it happened. I is OK to use .357 cases, but not with light loads. There is a strong warning about light loads that can explode on the first page and top paragraph of my web site . . . and that’s light loads in regular cases. Certainly you’d think someone would know that light loads in an even larger case could be a problem. Using a light load with a low density powder that would be light in a .38 case, is a very, very bad idea in a .357 case. Your theory as to what actually happens inside the case is as valid as any others I have heard for when this event occurs.
Yes, sometimes a double charge can do the same thing. And, with very light loads, a bullet can get lodged in the barrel and the next shot will blow up the gun. So that’s two things in addition to the “light loads explosion” that can happen. Case position of the powder with light loads is another issue. I have found (read my web site about powder position in cases) that velocities can vary tremendously with a small amount of powder in cases that were tilted forward or backwards before firing, so that the powder was full against the primer or the lead bullet.
Thanks for writing. Sorry your friend had to find out the hard way about small amounts of powder in large cases. I will share this with others.
DWalt
Member
I've done the same thing for many, many years. I started back sometime in the mid-1970s when I discovered (fortunately in time) that I had double charged some .44 Mag loads. Another plus to using that procedure is that it prevents squib loads. I have experienced some of those also.
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Anecdotes like these are hardly evidence. Anything could have happened. They couldn't figure out what happened yet they came to a conclusion. Not because of any evidence but because a faulty process of elimination. The load isn't listed, the powder density to case volume isn't defined. Why is it almost always the .38 Special? What is "very light"? What powder density to case volume causes this?
For years they were blaming 2.8 gr of Bullseye for blowing up all those Model 14's. Is that a "very light" load?
As the first guy said, multiple ballistic labs at manufacturers say it can't happen. But we're supposed to believe this anecdote over them? There's lots of reasons not to use very "light loads" but "detonation" isn't one of them.
I think it's more likely he made a mistake because he was unfamiliar with the Star. Those are more complex than your average beast.
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Agreed. Mostly…
I have used small charges of Red Dot and Unique to fire form .30-30 brass to .375 Win dimensions during the previous component shortage. However I also used corn meal as a filler on top of the charge to address the potential for detonation due to low load density. It also ensures the case fully forms and it eliminates the use of a bullet to fire form the case.
I have also used Unique in cast bullet .38-55 and .47-70 loads. In those loads I use a polyester wad made 3/4” or 1” square cut from 1/4” thick polyester quilt batting on top of the powder charge. That wad takes up most of the remaining internal volume. The wad prevents the charge from being blown forward and scattered by the primer and then consequently igniting much faster than normal creating a pressure spike.
However I’ve also noted some incipient pressure spikes in some very small rifle cartridges. For example when loading for accuracy in the .22 Hornet, I’ve noted rapidly increasing standard deviation in velocity toward the low end of published data. .22 hornet brass also tends to vary a lot in internal volume by manufacturer. Hornady brass has much less capacity than Remington for example, with Winchester, PPU and others being in between.
If you use a minimum load in the Hornady manual in Remington brass with certain powders, you’ll see some incipient pressure spikes evidenced by massively inconsistent shot to shot velocities. It’s your cue that going that low is a bad idea and going any lower is just plain dangerous.
I agree the theory about the powder laying in the bottom of the case and being ignited at both ends with resulting pressures waves starting at each end and meeting in the middle is suspect. In fact I’ll go one farther and say it’s total hogwash. The powder would not start burning at both ends, it would start burning along the entire exposed surface.
Generally speaking one of the concerns with extremely low load densities is that way too much powder is exposed to the primer flash, and or is scattered by the primer blast so that it is much more exposed to flame and ignites faster and creates a much larger initial pressure spike.
Why is the .38 special often implicated? Probably because it is a low pressure cartridge (17,500 psi) that started life in 1898 as a black powder cartridge. As such it has a very large internal volume by smokeless powders standards (which it started being loaded with as early as 1899).
The .357 Magnum was made 1/8” longer just to prevent it from being chambered in the .38 Special chamber. It’s also over sized for what it needs, but the larger charges used to generate the higher pressures (up to 35,000 psi) usually make that no more of an issue than it is in the .38 Special.
Where it all comes off the rails load density wise is when a hand loader wants a very light .38 Special target load but also wants to use it in a .357 Magnum case. Minimum charges for .357 Magnum are usually about 1 to 2 grains higher than for the .38 Special.
Looking at old (2nd edition) Hornady data, 2.5 grains of Bullseye is the minimum listed charge for the 148 gr LSWC and significantly there is a blank space to the left of it on the table (I.e. if you want a lower velocity use a different powder). The .357 data doesn’t show the 148 gr bullet but shows a minimum charge of 4.2 grains of Bullseye compared to 3.3 grains for the .38 Special.
The 11th edition shows a minimum charge of 2.1 grains of Bullseye for the same 148 gr LSWC bullet in the .38 special (and doesn’t show Bullseye data at all). Why would the significant 16%) difference in minimum charges exist? Two possibilities.
1) You’ll often see some minor differences in min or max charges due to lot to lot variation in a powder. For example look at H110 and Win 296, or HP38 and Win 231 data in most manuals. They are respectively the same powders wig different labels. Yet you will almost always see minor differences in min and max loads. That reflects lot to lot variation in the powder.
2) Despite having the same name, powder formulation for a given powder changes over time.
If you look at the gun powder data base for the National Center for Forensic Science…
National Center for Forensic Science
…you’ll find distinctly four different formulations for Bullseye dating from its production by both Hercules and Alliant:
1) Nitroglycerin and Ethyl centralite
2) Nitroglycerin, Ethyl centralite, and Dibutyl phthalate
3) Diphenylamine, Nitroglycerin and Ethyl centralite
4) Nitroglycerin, 2,4-Dinitrotoluene, Diethyl phthalate, Diphenylamine, Ethyl centralite, Dibutyl phthalate and 2-nitrodiphenylamine
I’m not a chemist but my understanding is that changes in established powders over time are the result of changes in production methods and costs as well as adding features like increases flash suppression, increased powder stability, reduced temperature sensitivity, etc.
In other words today’s Bullseye isn’t necessarily the same as yesterday’s Bullseye.
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How does that all relate to a light charge of Bullseye in a Model 14 and numerous case studies of one that have occurred over the years that claim a light charge of Bullseye in a .38 Special caused detonation and a kaboom?
Your argument is that ballistics labs claim it can’t happen. I am sure that is ***probably the case - but only within the parameters and experimental accuracy of their research. But that means a there are a lot of “ifs” involved:
- What formulation of Bullseye was used? What if your formulation of Bullseye is different?
- What did they consider a light charge? Did they keep reducing to 0 or did they stop at a minimum recommended charge weight? What if your “light charge” is different?
- What powder lot was used and where was it in respect to the range of powder burn traits for Bullseye? What if your powder is on the other end of the range?
- What was the water capacity of the brass used? What if your brass has slightly larger water capacity?
- What firearm or test barrel was used? What if your firearm isn’t as strong, has different chamber, leade or forcing cone dimensions?
All research has confidence intervals and qualifiers that have to be considered that effect the extent to which any conclusions can be generalized to other, let alone all other, cases. Not everyone summarizing that research mentions those qualifies and caveats that impact the limitations of the data.
*** I’ll stick with “probably” here as some of those labs may well have conducted the research for very specific legal purposes in response to law suits, or to proactively address concerns about future liability, and/or along very narrow constraints that may augment a legal defense but not necessarily capture all of the possible real world occurrences.
——
In short I am not going to discount a large number of reported (and admittedly potentially suspect) cases based solely on lab results that by definition have constraints that limit their application to the entire population of possible low low density kaboom events.
It’s much like the argument between the data junkies and the ballistic gel junkies. Ballistic gel gives repeatable (reliable) results, but those results lack any real meaning until you can compare a bullet’s lab results in ballistic gel with street results in a significant number of real world shoots.
At best you, all you can do is establish a range of performance in ballistic gel that is associated with an acceptable range of performance in real world shoots. Yet the gel junkies forget that last part of the sentence or the role that data on actual shoots plays in validating the gel data.
You need both.
