Kaboom 💥 Today 😟

[MagnumManiac]

Well, its been ruled as my fault. I am not disbelieving the notion, but I am surprised that a few thou stretching on 1X fired case causes the rupture.

I do not believe that for a second…that rupture occurred right where the case is turned for the extractor groove and where the extrusion occurs in the first punching of the cup.
Have seen this once before, the case let go right at the extractor groove cut…no stretching occurs there from firing…ever!
When I worked at ADI, we would get the cups from different lots of brass sheet, sometimes, the annealing wasn't enough and the cups would crack right at where the cases web would end. These would never see the light of day, but maybe, just maybe, one got through…
I have some of these somewhere, for 7.62 NATO brass, will post a pic when I find one.

Cheers.

 

[Pdvdh]

I honestly believe you don't know what you're talking about. An excessive pressure event, not a case failure, ALWAYS results in case FLOW into every possible recess in the bolt face, and obviously when the case ruptured due to a case defect, the gas was correctly directed into the mag well. Like it's supposed to…
My question to you is…how many ruptured firearms have you seen and how many have you determined the cause of such ruptures?
I have seen dozens in myriad of scenarios, such only 1 being caused by a case rupture very similar to this. Excessive pressure, nor excessive headspace caused any of this.

Wow. You completely rule out excessive pressure! You're very good reaching such definitive conclusions, based on several photographs and some descriptive posts. Next time the OP outta just PM you for the sole and definitive explanation of cause.

So easily angered in disagreement.
I do hope you find a way to manage that disagreeable anger in the future.

I owe you no explanations. I'm not angry, proud, or in need of your affirmation. Confident and content with myself. But you did ask me a question related to life experiences...

A nearby relative has been a practicing gunsmith for the past 40 years. So I've seen a few ruptured case heads, expanded leaky primer pockets, and the affected firearms that have come through his shop over those years. I've experienced several overpressured case head events of my own over the past 55 years of shooting and reloading rifle ammunition. Some simple expanded primer pocket leakage. A couple partial case head separations. And two high pressure events causing visibly enlarged and distorted case heads. But I'm certainly not claiming to be as all-knowing as you. You walk on water, never getting wet!

I've never seen a case head separate at the foreard edge of the extractor groove, where the OP stated this case separated. Where the cross-section of the case is solid brass, minus the flash hole and primer pocket.

Do I rule out excessive pressure? No.

Do I know this ruptured Lapua case was defective upon manufacture? No. And neither do you. Not based on the information available within this Thread.

 

[MagnumManiac]

It's such an amazingly clean break and evidence of a fracture remaining. I'm thinking bad brass too. Something might have happened during the initial drawing operation. Maybe a punch tooling change folded a void into it?
I'd be cutting some up just for education. The rest is scrap.
I'd volunteer my mill if you want to send a few.
Here is tutorial on Peterson's process.

Drawing Brass | How Cartridge Cases Are Made | Peterson Cartridge

See the brass rifle casing manufacturing process at Peterson Cartridge from raw brass coils to the finished casings we deliver to you.

www.petersoncartridge.com

Lapua extrude their brass, it results in much tighter tolerances in circumference dimensions and does not cause one side thicker than the other like drawing does. ADI also extrudes their brass 5.56 and 7.62 cases.

Cheers.

 

[MagnumManiac]

Wow. You completely rule out excessive pressure! You're very good reaching such definitive conclusions, based on several photographs and some descriptive posts. Next time the OP outta just PM you for the sole and definitive explanation of cause.

So easily angered in disagreement.
I do hope you find a way to manage that disagreeable anger in the future.

I owe you no explanations. I'm not angry, proud, or in need of your affirmation. Confident and content with myself. But you did ask me a question related to life experiences...

A nearby relative has been a practicing gunsmith for the past 40 years. So I've seen a few ruptured case heads, expanded leaky primer pockets, and the affected firearms that have come through his shop over those years. I've experienced several overpressured case head events of my own over the past 55 years of shooting and reloading rifle ammunition. Some simple expanded primer pocket leakage. A couple partial case head separations. And two high pressure events causing visibly enlarged and distorted case heads. But I'm certainly not claiming to be as all-knowing as you. You walk on water, never getting wet!

I've never seen a case head separate at the foreard edge of the extractor groove, where the OP stated this case separated. Where the cross-section of the case is solid brass, minus the flash hole and primer pocket.

Do I rule out excessive pressure? No.

Do I know this ruptured Lapua case was defective upon manufacture? No. And neither do you. Not based on the information available within this Thread.

I do rule out excessive pressure, because there was none…
You, like others, reach for the first thing you know from hearing what others say with zero fathomable knowledge, you make wild summations based solely on excessive pressure MUST be the cause…
I have zero qualms using the angry emoji in regard to your claims of gas cutting, fusing and whatever else terminology you used. It was clearly stated the case easily came out of the chamber, the case hadn't flowed into the bolt face…so, whenever a case lets go and gas is no longer contained within the barrel, an excessive pressure event is the result as the gas is unleashed, but it is NOT the cause in every instance. Is a squib load dangerous?
Anyhow, I bid you Good Day, and off to the ignore list you go, your opinions are based upon little factual expertise and you are just wasting my time.

Cheers.

 

[2buffalo]

I honestly believe you don't know what you're talking about. An excessive pressure event, not a case failure, ALWAYS results in case FLOW into every possible recess in the bolt face, and obviously when the case ruptured due to a case defect, the gas was correctly directed into the mag well. Like it's supposed to…
My question to you is…how many ruptured firearms have you seen and how many have you determined the cause of such ruptures?
I have seen dozens in myriad of scenarios, such only 1 being caused by a case rupture very similar to this. Excessive pressure, nor excessive headspace caused any of this.

If you have had that many "ruptured firearms" maybe you should work on your reloading skills instead of telling other people they don't know what they're talking about.

Cheers!

 

[Bob Wright]

Lapua extrude their brass, it results in much tighter tolerances in circumference dimensions and does not cause one side thicker than the other like drawing does. ADI also extrudes their brass 5.56 and 7.62 cases.

Cheers.

No, Lapua does the forming as a "drawing" operation. Can't find anything on ADI, yet.

 

[DoneNOut]

The case web brass isn't annealed, and isn't very malleable. It can stretch smaller amounts prior to separation. Not 0.080" - 0.100".

I meant the shoulder blowing that far to form the AI.

Good cases in properly chambered bolt actions only blow out where your's did under excessively high pressure.

My 708AI loads were deemed to be within acceptable parameters by Quickload.

BUT... that casing certainly could have been manufactured with a defect which compromised it's pressure containing strength. Causing it to rupture at normal cartridge pressures.

Yup, the mind bender here.

As someone else already suggested... I'd throw away the rest of that Lot of suspect Lapua casings. I'd also contact Lapua. Share your incident and pictures. Send them the ruptured casing, if they expressed the interest in running some laboratory tests. Since you didn't suffer any permanent debilitating injuries.

I did share the incident and pictures. I spoke of it in this thread. I did just add today.

 

[DoneNOut]

I greatly appreciate everyone's input on this. If anything, I've identified a step in my process I need to correct. That is to keep the 708 brass for fireforming long enough to be tight on the bolt closure. (At least if that isn't what did it, it is still good to know.)

Bob Wright has offered to mill some samples and send pictures. Hopefully some detailed close ups. So we all can see more on this issue.

 

[MagnumManiac]

If you have had that many "ruptured firearms" maybe you should work on your reloading skills instead of telling other people they don't know what they're talking about.

Cheers!

Did I say they were mine?
I am a gunsmith, I worked as warranty smith for both Remington and Winchester, I don't need to explain myself to you or anyone else. I actually know what I am talking about.
Off you go to the ignore list also.
Good Day…

 

[MagnumManiac]

No, Lapua does the forming as a "drawing" operation. Can't find anything on ADI, yet.

Well, that's not what I was told, and cups are punched, not drawn, which is what makes the case head.
I am happy to be corrected if that turns out to be the case.

Cheers.

 

[Orange Dust]

Could be headspace issue or reloading issue with too much shoulder setback, leading to thinning and case head separation.

Winner winner chicken dinner. Classic head separation. Exciting too. Back off the sizing die. Look for a tell tale light colored ring on the ormther cases. Section one and see the thinning. Throw them all away. You could have stretched them on the first firing. We always fireformed AI's with a bullet jamed in the lands to be certain we didn't stretch the brass forming it and shorten its life. Cases seemed to last forever formed this way with reasonable loads.

 

[Bob Wright]

Well, that's not what I was told, and cups are punched, not drawn, which is what makes the case head.
I am happy to be corrected if that turns out to be the case.

Cheers.

It's all drawn until it gets close to the head stamp and primer pocket, shoulder and necking It's covered in that Peterson link.
Extruding is a whole other process for easy shaping, but at high temperatures in a variety of metals. In that process you cannot or with difficulty, cold work the case head to increase its strength.

 

[Mark37082]

I greatly appreciate everyone's input on this. If anything, I've identified a step in my process I need to correct. That is to keep the 708 brass for fireforming long enough to be tight on the bolt closure. (At least if that isn't what did it, it is still good to know.)

Bob Wright has offered to mill some samples and send pictures. Hopefully some detailed close ups. So we all can see more on this issue.

I've learned something as well. I never went till tight on closing before bumping the shoulder as a normal practice. Even though I don't think this had anything to do with this particular brass failure, it is something I will add to my process. Sorry for your tough luck and glad you are okay.

 

[2buffalo]

Did I say they were mine?
I am a gunsmith, I worked as warranty smith for both Remington and Winchester, I don't need to explain myself to you or anyone else. I actually know what I am talking about.
Off you go to the ignore list also.
Good Day…