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Posted: 10/23/2014 2:38:20 PM EDT
[#1]
The discussion of incorrect powder got me curious as to actual case capacity. I took a empty LC brass case and filled it to the rim with various powders to see what kind of charge would be possible.
Clays : 14.2 gr W296: 31 gr Alliant 20/28 : 20.4 gr CFE223: 32.8 gr Blue Dot: 23.7 gr Just an FYI. IIRC my load is 23.4 gr of CFE223 (77 grain bullets). For severly compressed load you could get as much as a 40% overcharge. I was a little surprised that CFE223 and W296 are near the same density. |
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Posted: 10/23/2014 2:56:54 PM EDT
[#2]
Quote HistoryQuoted:
once heard about having the cartridge undercharged as a possibility of blowout. Guy said that if you have less than half the cartridge full of powder then the primer can blow across the top surface of the powder instead of igniting from the back. When this happens, he related that it all goes at once instead of in phase. Anyone? I didnt buy his ocean front property in AZ though. This is possible. |
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Posted: 10/23/2014 11:48:51 PM EDT
[#3]
I finally got the upper apart and this is the result:
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Posted: 10/23/2014 11:56:25 PM EDT
[#4]
There was a frightening amount of pressure involved in that case before it went if that isn't a brass failure.
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Posted: 10/23/2014 11:59:50 PM EDT
[#5]
Yep. Something definitely went wrong.
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Posted: 10/24/2014 12:03:19 AM EDT
[#6]
I'm almost thinking the shoulder got bumped back during the loading process creating an excessive headspace condition due to ammo dimensions and not the rifle.
Length of case? Length at shoulder? |
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Posted: 10/24/2014 12:09:39 AM EDT
[#7]
Quote HistoryQuoted:
I'm almost thinking the shoulder got bumped back during the loading process creating an excessive headspace condition due to ammo dimensions and not the rifle. Length of case? Length at shoulder? Well... The length now will not be the length before firing... |
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Posted: 10/24/2014 12:14:02 AM EDT
[#8]
Any guesses as to what happened to the back of the cartridge?
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Posted: 10/24/2014 12:16:30 AM EDT
[#9]
Extractors are strong.
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Posted: 10/24/2014 12:16:30 AM EDT
[#10]
I would reuse the bbl just for laughs. After running a chamber reamer in it.
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Posted: 10/24/2014 12:16:54 AM EDT
[#11]
The primer looks surprisingly close to normal.
On the other hand, huge brass flow into the ejector. Case head gave way at the weakest/unsupported location (extractor). Also, we know it fired with a locked bolt. But there's considerable swelling of the case... Strange. |
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Posted: 10/24/2014 12:22:07 AM EDT
[#12]
Quote HistoryQuoted:
Extractors are strong. That one is. There are crappy extractors though. |
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Posted: 10/24/2014 12:28:37 AM EDT
[#13]
Looks like a serious over-pressure. See how the case has been extruded into the ejector hole.
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Posted: 10/24/2014 12:29:49 AM EDT
[#14]
The case failed while chambered, and right at the extractor.
Did you post pics of cases he fired right before the failure? I'd be interested to see if there was extractor marks. |
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Posted: 10/24/2014 12:31:11 AM EDT
[#15]
Quote HistoryQuoted: Well... The length now will not be the length before firing... Quote HistoryQuoted: Quoted: I'm almost thinking the shoulder got bumped back during the loading process creating an excessive headspace condition due to ammo dimensions and not the rifle. Length of case? Length at shoulder? Well... The length now will not be the length before firing... |
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Posted: 10/24/2014 12:31:27 AM EDT
[#16]
Quote HistoryQuoted:
The primer looks surprisingly close to normal. On the other hand, huge brass flow into the ejector. Case head gave way at the weakest/unsupported location (extractor). Also, we know it fired with a locked bolt. But there's considerable swelling of the case... Strange. I don't see how both of these could be true at the same time, with the case swelling in the pics. The primer has a firing pin dent, so it doesn't look like a bolt-face-debris slamfire. But the deformation of the case looks like it could have been a slamfire of some sort. It seems to have fired with the cartridge not fully chambered. Which ARs don't do. Hmmm.... Also, the bolt lugs look pretty normal. Nothing sheared off or otherwise damaged. Maybe the firing pin was too long, allowing an OOB? Just throwing that out there. |
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Posted: 10/24/2014 12:35:05 AM EDT
[#17]
Holy Shitsnacks! that brass was flowing before it let go. My best guess is it was either pistol powder or the whole case got annealed at the factory. Its nice to know however that the AR vents the pressure out the ejection port and down through the mag, not towards the face.
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Posted: 10/24/2014 12:35:15 AM EDT
[#18]
Still going with OOB, unless the extension lugs were sheared.
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Posted: 10/24/2014 12:37:39 AM EDT
[#19]
Quote HistoryQuoted: I don't see how both of these could be true at the same time, with the case swelling in the pics. The primer has a firing pin dent, so it doesn't look like a bolt-face-debris slamfire. But the deformation of the case looks like it could have been a slamfire of some sort. It seems to have fired with the cartridge not fully chambered. Which ARs don't do. Hmmm.... Also, the bolt lugs look pretty normal. Nothing sheared off or otherwise damaged. Maybe the firing pin was too long, allowing an OOB? Just throwing that out there. |
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Posted: 10/24/2014 12:38:32 AM EDT
[#20]
1387delta-
what is this item in the red circle? 
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Posted: 10/24/2014 12:39:38 AM EDT
[#21]
Quote HistoryQuoted:
Any guesses as to what happened to the back of the cartridge? Massive Adrenaline Dump! 
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Posted: 10/24/2014 12:40:01 AM EDT
[#22]
Was wondering about oob based on the degree of flow of the brass just above the case head. It looks like a bellows.
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Posted: 10/24/2014 12:45:47 AM EDT
[#23]
Any chance of this stuff being reprocessed ammo fired out of a M249? I just am not buying the OOB idea.
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Posted: 10/24/2014 12:51:24 AM EDT
[#24]
Quote HistoryQuoted: Any chance of this stuff being reprocessed ammo fired out of a M249? I just am not buying the OOB idea. |
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Posted: 10/24/2014 12:57:55 AM EDT
[#25]
Quote HistoryQuoted:
and?... why do people think even once fired brass out of a MG is bad? Quote HistoryQuoted:
Quoted:
Any chance of this stuff being reprocessed ammo fired out of a M249? I just am not buying the OOB idea. Long standing reloader myth that m249 brass belongs in a scrap bucket. |
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Posted: 10/24/2014 1:02:13 AM EDT
[#26]
Quote HistoryQuoted:
Still going with OOB, unless the extension lugs were sheared. You don't know anything about AR kbooms then if after seeing these pics you think OOB had anything to do with this. |
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Posted: 10/24/2014 1:07:36 AM EDT
[#27]
Quote HistoryQuoted: Long standing reloader myth that m249 brass belongs in a scrap bucket. Quote HistoryQuoted: Quoted: Quoted: Any chance of this stuff being reprocessed ammo fired out of a M249? I just am not buying the OOB idea. Long standing reloader myth that m249 brass belongs in a scrap bucket. |
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Posted: 10/24/2014 1:11:29 AM EDT
[#28]
When sectioned, the case will look like this:
 That thick belt is formed in the gap between barrel face and bolt lug face. There is a chamfer on both and as you can see, while a normal gap is small (it varies a bit), that extreme bit of pressure will do its best to separate the two. Compared to a normal case cutaway there seems to be a lot of brass that flows. The flash hole approaches the size of a normal primer. Primer and pocket expand a huge amount. Web area inside the rim probably triples its mass, and the hunk of brass that creates joinder with the extractor cut ends up looking like a nice little gold nugget. A simple case rupture near the extractor (do those even happen?), due to a brass defect, will not force all of this brass to flow. Nor would it crack a bolt face or damage the BC. But, since we have (and nobody knows precisely why) a metric shit ton of pressure that exceeds the point where brass becomes a fluid, then your rifle blows the fuck up. It is no fault of the rifle, not an obstructed barrel, not an oob, not a case defect. You have magically achieved fusion with what little bit of powder that could be crammed into the case. |
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Posted: 10/24/2014 1:18:58 AM EDT
[#29]
OP:
1: What does the inside of the chamber look like? Any strange geometry? 2: Do you have another bolt laying around and a headspace gauge? Won't tell us everything due to another bolt, but if the barrel itself has crazy headspace you'd find out. Hell, try it if possible with the broken bolt for giggles, if it passes we can rule out headspace. If it fails though it could be due to damage. |
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Posted: 10/24/2014 1:21:29 AM EDT
[#30]
Quote HistoryQuoted: Long standing reloader myth that m249 brass belongs in a scrap bucket. Quote HistoryQuoted: Quoted: Quoted: Any chance of this stuff being reprocessed ammo fired out of a M249? I just am not buying the OOB idea. Long standing reloader myth that m249 brass belongs in a scrap bucket. |
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Posted: 10/24/2014 1:21:50 AM EDT
[#31]
Quote HistoryQuoted:
When sectioned, the case will look like this: http://i.imgur.com/mfTVcMo.jpg That thick belt is formed in the gap between barrel face and bolt lug face. There is a chamfer on both and as you can see, while a normal gap is small (it varies a bit), that extreme bit of pressure will do its best to separate the two. Compared to a normal case cutaway there seems to be a lot of brass that flows. The flash hole approaches the size of a normal primer. Primer and pocket expand a huge amount. Web area inside the rim probably triples its mass, and the hunk of brass that creates joinder with the extractor cut ends up looking like a nice little gold nugget. A simple case rupture near the extractor (do those even happen?), due to a brass defect, will not force all of this brass to flow. Nor would it crack a bolt face or damage the BC. But, since we have (and nobody knows precisely why) a metric shit ton of pressure that exceeds the point where brass becomes a fluid, then your rifle blows the fuck up. It is no fault of the rifle, not an obstructed barrel, not an oob, not a case defect. You have magically achieved fusion with what little bit of powder that could be crammed into the case. Listen to this guy. |
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Posted: 10/24/2014 1:23:19 AM EDT
[#32]
Quote HistoryQuoted:
When sectioned, the case will look like this: http://i.imgur.com/mfTVcMo.jpg That thick belt is formed in the gap between barrel face and bolt lug face. There is a chamfer on both and as you can see, while a normal gap is small (it varies a bit), that extreme bit of pressure will do its best to separate the two. Compared to a normal case cutaway there seems to be a lot of brass that flows. The flash hole approaches the size of a normal primer. Primer and pocket expand a huge amount. Web area inside the rim probably triples its mass, and the hunk of brass that creates joinder with the extractor cut ends up looking like a nice little gold nugget. A simple case rupture near the extractor (do those even happen?), due to a brass defect, will not force all of this brass to flow. Nor would it crack a bolt face or damage the BC. But, since we have (and nobody knows precisely why) a metric shit ton of pressure that exceeds the point where brass becomes a fluid, then your rifle blows the fuck up. It is no fault of the rifle, not an obstructed barrel, not an oob, not a case defect. You have magically achieved fusion with what little bit of powder that could be crammed into the case. I agree with you. I just checked a barrel on hand, there is enough unsupported case for that "belted magnum" appearance to form if there is enough pressure. |
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Posted: 10/24/2014 1:23:52 AM EDT
[#33]
Quote HistoryQuoted:
The M249 has a longer head space gauge than a M16. Obviously not all M249s kill brass, but use in a 249 could make a case more likely to experience case head separation upon reloading and firing it. Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
Any chance of this stuff being reprocessed ammo fired out of a M249? I just am not buying the OOB idea. Long standing reloader myth that m249 brass belongs in a scrap bucket. The same is true for machine gun fired 7.62. Had a ton of brass with thin webs, you could feel the thin spot. |
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Posted: 10/24/2014 1:24:46 AM EDT
[#34]
OP... What's the rifling look like? Any "holy shit, what happened there?" oddities?
I know a squib was supposedly ruled out, but just to verify... |
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Posted: 10/24/2014 1:30:49 AM EDT
[#35]
Quote HistoryQuoted:
You don't know anything about AR kbooms then if after seeing these pics you think OOB had anything to do with this. Quote HistoryQuoted:
Quoted:
Still going with OOB, unless the extension lugs were sheared. You don't know anything about AR kbooms then if after seeing these pics you think OOB had anything to do with this. Good comment, please don't give any further explanation. |
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Posted: 10/24/2014 1:43:19 AM EDT
[#36]
The flow of the brass into the ejector hole combined with the still dented primer leads me to believe that the firing pin was jammed with debris and protruding when the KBed round chambered.
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Posted: 10/24/2014 3:21:39 AM EDT
[#37]
Quote HistoryQuoted:
Good comment, please don't give any further explanation. Quote HistoryQuoted:
Quoted:
Quoted:
Still going with OOB, unless the extension lugs were sheared. You don't know anything about AR kbooms then if after seeing these pics you think OOB had anything to do with this. Good comment, please don't give any further explanation. An AR-15 is incapable of firing via the firing pin unless the bolt is locked. Thus, it did not fire OOB. Got a BCG laying around? Play with the bolt/firing pin a bit. You should figure it out. |
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Posted: 10/24/2014 3:23:00 AM EDT
[#38]
Quote HistoryQuoted:
The flow of the brass into the ejector hole combined with the still dented primer leads me to believe that the firing pin was jammed with debris and protruding when the KBed round chambered. That would not cause this. Even if forced as far forward as possible, the firing pin cannot contact the primer until the lugs are locked. That's the way the gun works. |
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Posted: 10/24/2014 3:38:45 AM EDT
[#40]
Quote HistoryThat's really impressive. |
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Posted: 10/24/2014 3:46:40 AM EDT
[#41]
Quote HistoryQuoted:
That would not cause this. Even if forced as far forward as possible, the firing pin cannot contact the primer until the lugs are locked. That's the way gun works. Quote HistoryQuoted:
Quoted:
The flow of the brass into the ejector hole combined with the still dented primer leads me to believe that the firing pin was jammed with debris and protruding when the KBed round chambered. That would not cause this. Even if forced as far forward as possible, the firing pin cannot contact the primer until the lugs are locked. That's the way gun works. TXRifleman's right. Just to explore that briefly and totally rule out the impossible... if there was debris in the way of the firing pin that could somehow do this - where the debris would do the strike (because the pin cannot), it wouldn't leave a conventional mark in the primer. The dent in the primer as shown in one of the photos shows it was a regular strike to start with. So that's totally out. In order for debris to block the firing pin forward - like TXR85 says, that's not the way the gun works - so the gun would have to be working improperly - horribly out of spec. The bolt would have to be too short, or the firing pin abnormally long. But that would've hindered operation immediately or kaboomed immediately. So that's totally out. |
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Posted: 10/24/2014 3:59:10 AM EDT
[#42]
Quote HistoryQuoted:
TXRifleman's right. Just to explore that briefly and totally rule out the impossible... if there was debris in the way of the firing pin that could somehow do this - where the debris would do the strike (because the pin cannot), it wouldn't leave a conventional mark in the primer. The dent in the primer as shown in one of the photos shows it was a regular strike to start with. So that's totally out. In order for debris to block the firing pin forward - like TXR85 says, that's not the way the gun works - so the gun would have to be working improperly - horribly out of spec. The bolt would have to be too short, or the firing pin abnormally long. But that would've hindered operation immediately or kaboomed immediately. So that's totally out. Quote HistoryQuoted:
Quoted:
Quoted:
The flow of the brass into the ejector hole combined with the still dented primer leads me to believe that the firing pin was jammed with debris and protruding when the KBed round chambered. That would not cause this. Even if forced as far forward as possible, the firing pin cannot contact the primer until the lugs are locked. That's the way gun works. TXRifleman's right. Just to explore that briefly and totally rule out the impossible... if there was debris in the way of the firing pin that could somehow do this - where the debris would do the strike (because the pin cannot), it wouldn't leave a conventional mark in the primer. The dent in the primer as shown in one of the photos shows it was a regular strike to start with. So that's totally out. In order for debris to block the firing pin forward - like TXR85 says, that's not the way the gun works - so the gun would have to be working improperly - horribly out of spec. The bolt would have to be too short, or the firing pin abnormally long. But that would've hindered operation immediately or kaboomed immediately. So that's totally out. Also the rear inner shelf of the carrier and the cam pin channel could, in theory, be altered in such a way as to allow OOB ignition. But if they were, you would know it right away, as you said. |
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Posted: 10/24/2014 4:03:26 AM EDT
[#43]
Quote HistoryQuoted:
- Also the rear inner shelf of the carrier and the cam pin channel could, in theory, be altered in such a way as to allow OOB ignition. But if they were, you would know it right away, as you said. Quote HistoryQuoted:
- Also the rear inner shelf of the carrier and the cam pin channel could, in theory, be altered in such a way as to allow OOB ignition. But if they were, you would know it right away, as you said. Yup. And from the OP: He has put about 250 rounds through the rifle. Thus those impossibilities are wholly ruled out. |
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Posted: 10/24/2014 4:04:25 AM EDT
[#44]
Quote HistoryQuoted:
1387delta- what is this item in the red circle? http://i857.photobucket.com/albums/ab138/le_pew/ftk5k8_b_zps4afc5135.jpg Looks like part of the anvil from the primer cup. |
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Posted: 10/24/2014 4:43:48 AM EDT
[#45]
Fired out of battery.
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Posted: 10/24/2014 6:09:41 AM EDT
[#46]
The OOB stuff is funny.
If it was even possible it would blow the whole head off. Massive over pressure on that round. The ejector intrusion is impressive. Two much/wrong powder. |
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Posted: 10/24/2014 8:01:35 AM EDT
[#47]
Quote HistoryQuoted:
Fired out of battery. Where do you people come from??? |
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Posted: 10/24/2014 8:07:23 AM EDT
[#48]
Quote HistoryQuoted:
The primer looks surprisingly close to normal. On the other hand, huge brass flow into the ejector. Case head gave way at the weakest/unsupported location (extractor). Also, we know it fired with a locked bolt. But there's considerable swelling of the case... Strange. This. It was a case failure, i thought for sure pistol powder but nope. Case failure. Had it been pistol powder the primer would have blown threw. Seeing it doesnt show any signs of over pressure the only possible cause was case failure. Scary.
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Posted: 10/24/2014 8:22:16 AM EDT
[#49]
Quote HistoryQuoted:
Where do you people come from??? Quote HistoryQuoted:
Quoted:
Fired out of battery. Where do you people come from??? 
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Posted: 10/24/2014 8:41:59 AM EDT
[#50]
Quote HistoryQuoted:
This. It was a case failure, i thought for sure pistol powder but nope. Case failure. Had it been pistol powder the primer would have blown threw. Seeing it doesnt show any signs of over pressure the only possible cause was case failure. Scary. Quote HistoryQuoted:
Quoted:
The primer looks surprisingly close to normal. On the other hand, huge brass flow into the ejector. Case head gave way at the weakest/unsupported location (extractor). Also, we know it fired with a locked bolt. But there's considerable swelling of the case... Strange. This. It was a case failure, i thought for sure pistol powder but nope. Case failure. Had it been pistol powder the primer would have blown threw. Seeing it doesnt show any signs of over pressure the only possible cause was case failure. Scary. No sign of over pressure? What caused the brass flow into the ejector bore?? |
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