The Down Range Forum
Member Section => Down Range Cafe => Topic started by: alfsauve on November 05, 2023, 11:50:01 AM
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Had a case head blow out today. Second shot of a local match. Darn. Took the extractor along with it. My Sig P320.
1) Double Charge: Unlikely as the charge fills the case by half.
2) Detonation: Remote, though I am running at the suggested low-end charge.
3) Case Head fault: I think most likely.
The data: 3.2gr TiteGroup, mixed lot cases, Fed 100 Primer, Xtreme 147gr Plated, 1.12" COL.
The slide cycled, though I can't remember whether it felt unusual. Blowback in the face and on the strong hand. Extractor broke off and hit the trigger finger. Small welt. Can't find the extractor. Went to an unused range and fired another round. No problem other than FTE. Barrel, FCG, frame and slide all look okay.
Oh, and that round scored -0 with a clean hole and no shrapnel in the target. SO didn't get hit with any blow back.
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Oops....
Glad you're ok.
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Ouch and wow.
I would think if you had a detonation you would have felt additional recoil. Detonations can be more violent than normal explosions. I worried about that in hydrocarbon piping whenever we opened up for maintenance.
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Looks like the something caused it to fire before it was in battery.
Is it possible something happened during the first round that caused the striker to hang up? That would cause a slam fire situation, and the primer got enough pressure to detonate while still not in the chamber.
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Looks like the something caused it to fire before it was in battery.
Is it possible something happened during the first round that caused the striker to hang up? That would cause a slam fire situation, and the primer got enough pressure to detonate while still not in the chamber.
That's the first thing I thought when looking at the photo. That much damage in that area looks like unsupported surface eruption. I've seen it in those "Perfected Pistols" but don't know about the Sig guns as I do not own any.
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I was going to say out of battery discharge from the looks of the case(What's left of it) Most likely an out of spec case didn't allow it to go fully into battery.
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Good insight followups guys!!
Nice to see you around Marshal!
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Wow. I've never seen a blowout like that before. I'm glad you're okay Alf. I only had a case head blow out once, and that was on a .22 LR. It was just a piece of the rim, and the rest of the case was fully supported in the chamber. It blew the extractor and related parts out of my 10/22, but it still worked most of the time while I finished that mag, or that box full of ammo. I can't recall now which it was, but the cases blew back into the ejector and out of the gun the majority of the time. Like Mike said, that looks like it fired out of battery. My guess is the case was oriented the opposite way, and the big gaping hole is what caused the extractor to blow out of the gun.
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Actually the blow out was downward. The picture below I've put the case back in the barrel and it only fits one way, since it's been "fire formed". For those curious it was an S&B brass "22" or "21" marking. Year of manufacture? And I chamber check all cases after sizing and again after I finish loading.
The very top of the head is not supported in Sig nor Glock. Even it it was there has to be space for the extractor so some portion would be unsupported. Even revolvers don't have fully supported heads if they use moon clips.
It was a purposeful shot, for those suggesting the P320 fired on it's own. I aimed and pulled the trigger. (Down Zero/bullseye shot) I've had other guns go double on me so I know what that feels like.
I'll play with it and my feeler gauge but I don't think out of battery was the issue.
ON SIG EXTRACTORS. I had assumed, like a number of guns the extractor pivoted on a pin. I've never paid much attention to how the SIG works. Turns out they free float in their slot and are held in place buy a pin that slides longitudinally pushing on the rear section of the extractor.. Unlike, say an AR extractor, this one is U shaped. Makes it very easy for them to blow out, like this one did, with out shearing anything. Had I known I'd spent more time searching for the missing piece.
I've replaced the extractor and run tests with dummy rounds all seems to work fine. Am going to the range shortly to live fire it.
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Could've just been a "tired old" case or weak spot where the case was formed.
I saw that once with a low pressure .45 ACP round. The case ruptured and blew down the magwell and split the left grip panel.
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Ran 100 rounds it. All functioned well. No failures. I did do the first 10 left handed, just in case. I did slow fire and very fast doubles.
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I m going to go with a case that was either " worn out" or some one loaded it very hot,it could not take another loading.
I am not sure you could have double charged it and if it was an over charge there would have been other signs
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The load, 3.2gr of TG, fills just over half the case. Double charging would hard to overlook as the bullet wouldn't even seat.
It was an S&B case made in 21-22 (Covid era). I can't be sure if it was from my S&B 115gr stock ammo or not. It comes out of a 5gal bucket of 9mm brass. The top of which tend to get reloaded over and over since I don't have a way to rotate the stock. Just dump the ones I bring home in the top. So it could have been reloaded many times. However, other S&B brass I've scooped out at the same level of the bucket are crimped which tell me they are all factory, once fired.
On that note, for .357 and .44 magnum I do keep two bins each. One is labeled "DUMP" where I dump all spent brass. The other bin is used for reloads until empty. Then I swap the sign. That way I'm rotating stock. Don't do it for 9mm and .38spl though. I may start!
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Okay, now that I see the feed ramp, it makes sense that the bottom blew out. And a little on the right side too. Since it wasn't out of battery when you fired, I think it looks like the gun unlocked before the bullet cleared the muzzle, and it blew up as the case was withdrawing, but I don't see how that's possible. This is a real puzzler for me. I'm used to looking at things going wrong with guns and knowing what happened, or at least having a really good idea, but not this time. No matter how weak the case was, I just don't see how that happened, but I haven't seen many ruptured cases. Maybe they do that sometimes, but the only case failure I had with a centerfire was a split case on a .45 ACP. It was enough pressure to split the case halfway, but nothing happened to the gun and the case could still be chambered. That was either in my Series 80 Colt or Para-Ordnance. It happened so long ago I can't remember which.
So, I have a question for everyone. Is it normal for a ruptured case to bulge in front of the rim out like that? This is a picture i just found of a ruptured case that blew out where it wasn't supported by the feed ramp, and it doesn't look anything like that.