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.
Can you see me now?
I see no photo and need additional info; what firearm used, bullet, case, powder and charge?
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.
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.
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.
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.
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.
Oh Lord. That’s way more bulging than I expected to see. Going to definitely need a small base die to resize! :sarcastic:
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”.
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!
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.
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.
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.
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.