View Full Version : What caused this
This photo was posted in another forum, would using too slow a powder and high port pressure cause the case to balloon on extraction. And if it were a out of battery firing wouldn't the base of the case have ruptured? I have never seen anything like this before and have been reloading for over 47 years.
https://www.ingunowners.com/forums/attachment.php?attachmentid=72523&d=1543891992
Can you see me now?
https://i.imgur.com/UEJNjqE.jpg
I see no photo and need additional info; what firearm used, bullet, case, powder and charge?
Ned Christiansen
12-04-18, 14:56
Gonna guess it's a bulged .223.... they "look" like it must have been out of battery when it bulged but really they're just bulging into normally-occurring, available space, that being the chamfer at the back of the chamber and the chamfer at the mouth of the bolt face recess. If I'm right, what you have is a round that was over pressure for some reason and the gun was within half a PSI of getting blown up.
With no pic, I'm also guessing .223. I've only seen bulging on my Wylde chamber with hotter loads of .223.
thopkins22
12-04-18, 16:10
I can’t see the photo on my iPad, but things have to be really out of spec to fire out of battery. Like really out of spec to the point that even when all the evidence points to that happening I’d still be skeptical and look for something else that could have happened...likely what Ned suggested.
Ned Christiansen
12-04-18, 19:37
Hm. Look how short the necks are. The dimension from the base to the top of the bulge is longer than expected, longer than the distance from the bolt face to the end of the chemfer lead-in to the chamber (unless it's way, way deep. Those short necks are telling us something, just not sure what, yet.....
Has this gun been fired before successfully, has anything recently been changed (bolt, barrel), any chance this is .222 ammo?
Maybe the necks are getting short because the brass to make that bulge hadda come from somewhere. In which case.... looking at that lead-in chamfer again.
Kansaswoodguy
12-04-18, 20:15
Incipient head separation maybe or to light of buffer idk that’s a new one on me
Like others say, also gonna guess bulged/over pressuer .223, maybe with a soft or thin brass at the head.
Even with a slow powder in a carbine gassed 16", I can't see unlocking happening prior to the bullet leaving the barrel, and if it did, the head would separate and blow out and not just bulge. In other words, the bulge is evidence that the base was supported during the pressure event.
1_click_off
12-05-18, 07:48
Wonder if there is a broken neck in the chamber keeping it just far enough in battery it fires, then the forces slide it back enough for the bulge.
^^^ check this. Possible bolt not fully locking and unlocking too soon. Details of rifle/load might help.
Ned,
I think you're on to something.
My first thought is something like massive excess head space to explain the short necks, but the improper chamber mouth seems to fit too.
Hm. Look how short the necks are. The dimension from the base to the top of the bulge is longer than expected, longer than the distance from the bolt face to the end of the chemfer lead-in to the chamber (unless it's way, way deep. Those short necks are telling us something, just not sure what, yet.....
Has this gun been fired before successfully, has anything recently been changed (bolt, barrel), any chance this is .222 ammo?
Maybe the necks are getting short because the brass to make that bulge hadda come from somewhere. In which case.... looking at that lead-in chamfer again.
Oh Lord. That's way more bulging than I expected to see. Going to definitely need a small base die to resize! :sarcastic:
Ned Christiansen
12-05-18, 11:44
If they were .222 or something they ought not to fire as they would be kicked too far forward upon chambering. I saw this just a month ago when a Dept. was having misfires with some commercial reloads. The necks were verrry long-- rounds were not being "stopped" by the shoulder, so the extractor could not clip over the rim and the firing pin could not reach. Some did work so they were borderline.
I think it's the chamber mouth chamfer. Can we get a pic of it?
-----
I just re-read the OP and I see we are dealing with something a place or two removed from "it happened to me". This reminds me that anything can happen when people start improving things and unless we can get closer to the situation I wonder if it even merits further discussion. Not casting aspersions on you OP, it's an interesting ocurrence, but can you bring this any closer?
The person who posted the photo said it was range pickup brass and that's all the information I have. I have never seen anything like this and I hoped possibly some of you might have.
It was my understanding with a M1 Garand with the gas port near the muzzle the bullet left the barrel before the bolt could move. But with a M14 and M16 with the gas port at mid barrel there is still pressure in the barrel when the bolt starts to move to the rear. I read that it was possible for a ejected case to be longer than the chamber because the residual pressure would push the case shoulder forward.
My first guess was the case was fired in a AR15 with a pistol length gas system and the residual pressure caused the bulge at the rear of the case. Meaning the bolt was closed and locked when the cartridge fired and high port pressure caused the case bulge.
So is there enough or any residual pressure in the barrel when the bolt starts moving to the rear to cause bulge at the base of this case. The case rims in the extractor groove are cracked, so was this caused by the extractor yanking on the rim. Just looking for other opinions by people who know more than I do about "how do it work".
Ned Christiansen
12-05-18, 14:15
Your guess sounds reasonable.... back to "anything can happen". If that's it, like a way-too-big pistol-length gas port, man the timing is just a bazillisecond from blowing up instead of bulging!
Hm. Look how short the necks are...
Maybe the necks are getting short because the brass to make that bulge hadda come from somewhere
I don't think it's that the brass from the necks wound up in the bulge.
I think it's that the whole case is ballooned, which pushed the shoulder waaaay forward — think of how wildcatters "improve" cartridge cases.
Wonder if there is a broken neck in the chamber keeping it just far enough in battery it fires, then the forces slide it back enough for the bulge.
This ^^
kwg
thopkins22
12-05-18, 23:35
This ^^
kwg
Nah. This state doesn’t exist on an AR...if this was an AR that is I guess.
Take your bolt carrier out and play with it. The bolt begins locking up as soon as the carrier starts sliding forward around it. The firing pin is incapable of protruding until the bolt has rotated almost the entirety of its path meaning it is completely in battery and completely locked up behind the lugs on the extension before anything else happens.
I suppose technically debris could lodge perfectly between the bolt face and the primer...but outside of that it just ain’t happening.
thopkins22
12-05-18, 23:46
I don't think it's that the brass from the necks wound up in the bulge.
I think it's that the whole case is ballooned, which pushed the shoulder waaaay forward — think of how wildcatters "improve" cartridge cases.
I think this is the ticket.
My guess echos Ned’s earlier supposition that somehow he managed to get a .222 Remington cartridge to go bang in a .223 or 5.56x45 chamber which would account for the shoulder getting fireformed all the way up into the neck, and maybe could have led to the high pressure somehow that led to the case ballooning into the voids back at the head.
Edited because I mixed up chamber and case in my post as Ned pointed out below.
Ned Christiansen
12-05-18, 23:57
Actually I was thinking a .222 in the .223 chamber. I mean, it would go but should not fire.... but it's not impossible. I would say a .223 in a .222 chamber, with the bolt so far out of battery, it would never fire.
thopkins22
12-06-18, 00:25
Actually I was thinking a .222 in the .223 chamber. I mean, it would go but should not fire.... but it's not impossible. I would say a .223 in a .222 chamber, with the bolt so far out of battery, it would never fire.
That’s what I meant...mixed up chamber and cartridge in my post.
Given that we don’t know what firearm was at play, I think it’s entirely possible that a controlled round feed/claw extractor held the round in place against the breech face. It would explain a lot...but who the hell does it twice?
Ned Christiansen
12-06-18, 08:20
Bubba! :-)
The case was marked Lake City, below is the original link. And I had hoped someone here had seen this happen before and now we have a mystery.
Found this in my brass bucket, what caused it?
https://www.ingunowners.com/forums/ammunition-reloading/462040-found-my-brass-bucket-what-caused-2.html#post7748284
Now I think the case ejected at the speed of light and hit "warp speed". :lol:
https://i.imgur.com/DRTtXSY.jpg
My friend had a polish tantal that did this, though not as bad- but it was steel cased ammo 5.45.
I believe he sold it, full disclosure due to the issue. I disnt know enough at the time to really dig in. We just assumed an out of spec chamber.
No that I think of it, a friend's Makarov did this to .380ACP brass. (Yes, it was chambered in 9x17, not 9x18.)
The Makarov only bulged brass on one side, so we figured it was that the feed ramp wasn't supporting the cases enough.
Gross headspace problem or out of battery. Not something I would attempt to duplicate.
Overpressure, bolt's unlocking with chamber still under enough pressure to deform the case as it extracts.
Bad, bad juju.
No that I think of it, a friend's Makarov did this to .380ACP brass. (Yes, it was chambered in 9x17, not 9x18.)
The Makarov only bulged brass on one side, so we figured it was that the feed ramp wasn't supporting the cases enough.
Yeah. Glocks are known for this... at least in 40 cal. Some company even made the Glock Rx die to remove the buldge.
Yeah. Glocks are known for this... at least in 40 cal.
I keep hearing this, but I've never seen it.
I have seven Glocks chambered in .40 (most of my pistols are .40 Glocks).
I've fired tens of thousands of rounds through them, and I've never seen a bulged case, including shooting high-pressure Gold Dots and the like.
I've seen it on my gen 2. I didn't know what it was at first...
I've seen it on my gen 2.
Six of my seven .40 Glocks are Gen2. (I never got used to the finger grooves.) No bulges, ever...
If my memory serves me, It was Blazer Brass ammo. Since I don't load 40, I never get a good look at the brass anymore. Maybe I'll shoot a few rounds next weekend to see.
Glacierwolf
02-16-19, 22:34
Seen this before. The person who posted said it was range pickup brass - not something they fired. This looks to be a round from a 223cal bang stick used by divers. You get the bulge when the darn thing is not screwed in tight like it should. I had a 223 bang stick back in 1983 when diving around Florida. I made a piece of brass like this once - only not as bad - when some sand got into the threads and I didn't have the chamber section screwed down and seated in tight.
Kevin
I've seen this with dirty open bolt 9mm FA.
Makes me wonder if this was a very dirty/misadjusted SAW or similar. Not an AR.
I've seen this with dirty open bolt 9mm FA.
Makes me wonder if this was a very dirty/misadjusted SAW or similar. Not an AR.
I don’t know exactly what I’m looking at, but I’ve never seen it with a SAW or Mk46. Neither have user adjustable headspace, if that’s what you're getting at. Maybe if there was a case neck stuck in the chamber, as someone mentioned earlier?
I am not familiar enough with the saw other than internet reading to know.
But really looks like out of battery, and you know the AR won't do this. OOB, anyway.
Personally, I don't think it was premature extraction. If the residual pressure was enough to swell the case, it would have still had major friction with the chamber almost by definition. And would have ripped the rim off or similar.
So I'm thinking OOB, and probably open bolt of some kind. (But what?)
Did not think about bang sticks, back in the day they used 38 special.
After some thinking, I don’t think a SAW can OOB. The bolt must rotate closed in order for the firing pin to protrude. I’ll have to get my mitts on one to be sure.
Perhaps a closed bolt gun like an AR or AK with a seized firing pin slam firing?
I believe you are correct. It's not a fixed firing pin. And the bolt has to advance to a certain point before it protrudes as I understand it.
thopkins22
02-19-19, 09:49
After some thinking, I don’t think a SAW can OOB. The bolt must rotate closed in order for the firing pin to protrude. I’ll have to get my mitts on one to be sure.
Perhaps a closed bolt gun like an AR or AK with a seized firing pin slam firing?
I can’t speak to an AK, but the AR cannot have a seized firing pin. If you welded it forward, you would never be able to retract the bolt. It is impossible by design for the firing pin to be anywhere near the breech face until the bolt is well and fully locked up.
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