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Posted: 10/24/2014 9:05:01 AM EDT
[#1]
$15 CH, $35 upper, $79 BCG, reuse same bbl and back in business.
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Posted: 10/24/2014 9:07:55 AM EDT
[#2]
Quote HistoryQuoted: No sign of over pressure? What caused the brass flow into the ejector bore?? Quote HistoryQuoted: Quoted: 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?? If the case head had somehow been annealed or more likely, if the case was improperly drawn, this WILL happen. For instance, a thin case head would be unsupported and then one leak leads to plasma cutting of the brass, making that brass patina seen on the carrier, bolt and rifle.
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Posted: 10/24/2014 9:13:19 AM EDT
[#3]
A brief review of what is known:
1. Not on OOB, as the case failure was wrong. 2. Massive overpressure (duh). 3. Bore is clear of obstructions. 4. Bolt lugs are intact, for the most part. So it appears the case chambered okay and ignited okay. Then things go bad. So, possible problems include: 1. The case was loaded with much more energetic powder than rifle powders (e.g., pistol powder) 2. Bore was obstructed and the bullet from this cartridge forced the obstruction out, leaving a clear bore. 3. Something other than an obstruction caused the bullet not to travel down the barrel In the correct manner. Other kabooms where the wrong powder was used look like this, but absent chemical testing we'll never know for sure. If an obstructed bore was cleared by this bullet, there should be some evidence in the barrel that a borescope might reveal. But I am wondering what might happen if this case had a seriously out of spec bullet, specifically something the about the size of a 5.76mm or even a 6mm (.243) bullet. The bullet shown has a BT, so it would fit into the case mouth during loading. The neck could have been thinned enough to allow chabering, and the protruding bullet would not necessarily have contacted the rifling, keeping the case from seating. But at firing, the bullet has to deform to fit down the bore, and that completely changes the shape of the pressure curve, possibly enough to reach the failure point of the gun. Just an idea to consider. |
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Posted: 10/24/2014 9:18:59 AM EDT
[#4]
Quote HistoryQuoted: Lake City is the brass but I would bet a grand it was not assembled and packaged in Lake City Army Ammunition Plant. That is a GOCO plant, government owned contractor operated. All produced ammo is property of the US government and cannot be sold or diverted. Only components that are non explosive can be salvaged, primers must be rendered inert. As much as I hate to argue with Keith J, that statement is not correct. Explosive components can be salvaged and re-sold, I work for an explosives recycling and waste management company and Lake City/ATK send us stuff quite often. As long as the ammunition does not stay intact, so you pull the bullet and powder, and sell it as component parts, its OK. |
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Posted: 10/24/2014 9:47:50 AM EDT
[#5]
Quote HistoryQuoted: As much as I hate to argue with Keith J, that statement is not correct. Explosive components can be salvaged and re-sold, I work for an explosives recycling and waste management company and Lake City/ATK send us stuff quite often. As long as the ammunition does not stay intact, so you pull the bullet and powder, and sell it as component parts, its OK. Quote HistoryQuoted: Quoted: Lake City is the brass but I would bet a grand it was not assembled and packaged in Lake City Army Ammunition Plant. That is a GOCO plant, government owned contractor operated. All produced ammo is property of the US government and cannot be sold or diverted. Only components that are non explosive can be salvaged, primers must be rendered inert. As much as I hate to argue with Keith J, that statement is not correct. Explosive components can be salvaged and re-sold, I work for an explosives recycling and waste management company and Lake City/ATK send us stuff quite often. As long as the ammunition does not stay intact, so you pull the bullet and powder, and sell it as component parts, its OK. What explosives can they sell? The only explosive in a cartridge is the primer. The powder is a propellant.
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Posted: 10/24/2014 10:15:46 AM EDT
[#6]
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.  |
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Posted: 10/24/2014 10:18:25 AM EDT
[#7]
Quote HistoryQuoted: As much as I hate to argue with Keith J, that statement is not correct. Explosive components can be salvaged and re-sold, I work for an explosives recycling and waste management company and Lake City/ATK send us stuff quite often. As long as the ammunition does not stay intact, so you pull the bullet and powder, and sell it as component parts, its OK. Quote HistoryQuoted: Quoted: Lake City is the brass but I would bet a grand it was not assembled and packaged in Lake City Army Ammunition Plant. That is a GOCO plant, government owned contractor operated. All produced ammo is property of the US government and cannot be sold or diverted. Only components that are non explosive can be salvaged, primers must be rendered inert. As much as I hate to argue with Keith J, that statement is not correct. Explosive components can be salvaged and re-sold, I work for an explosives recycling and waste management company and Lake City/ATK send us stuff quite often. As long as the ammunition does not stay intact, so you pull the bullet and powder, and sell it as component parts, its OK. Pull down propellants used to be quite common in reloading circles.
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Posted: 10/24/2014 10:21:08 AM EDT
[#8]
Quote HistoryQuoted: Yup. And from the OP: Thus those impossibilities are wholly ruled out. Quote HistoryQuoted: Quoted: - 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 10:21:53 AM EDT
[#9]
Quote HistoryQuoted: Fired out of battery.  |
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Posted: 10/24/2014 10:23:09 AM EDT
[#10]
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. |
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Posted: 10/24/2014 10:23:47 AM EDT
[#11]
Quote HistoryQuoted: $15 CH, $35 upper, $79 BCG, reuse same bbl and back in business. |
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Posted: 10/24/2014 10:26:14 AM EDT
[#12]
Quote HistoryQuoted: A brief review of what is known: 1. Not on OOB, as the case failure was wrong. 2. Massive overpressure (duh). 3. Bore is clear of obstructions. 4. Bolt lugs are intact, for the most part. So it appears the case chambered okay and ignited okay. Then things go bad. So, possible problems include: 1. The case was loaded with much more energetic powder than rifle powders (e.g., pistol powder) 2. Bore was obstructed and the bullet from this cartridge forced the obstruction out, leaving a clear bore. 3. Something other than an obstruction caused the bullet not to travel down the barrel In the correct manner. Other kabooms where the wrong powder was used look like this, but absent chemical testing we'll never know for sure. If an obstructed bore was cleared by this bullet, there should be some evidence in the barrel that a borescope might reveal. But I am wondering what might happen if this case had a seriously out of spec bullet, specifically something the about the size of a 5.76mm or even a 6mm (.243) bullet. The bullet shown has a BT, so it would fit into the case mouth during loading. The neck could have been thinned enough to allow chabering, and the protruding bullet would not necessarily have contacted the rifling, keeping the case from seating. But at firing, the bullet has to deform to fit down the bore, and that completely changes the shape of the pressure curve, possibly enough to reach the failure point of the gun. Just an idea to consider. |
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Posted: 10/24/2014 10:31:46 AM EDT
[#13]
There have been a few kabooms with 300AAC in a .556 gun so in theory it is possible. Quote HistoryQuoted:
Wouldn't chamber Quote HistoryQuoted:
Quoted:
A brief review of what is known: 1. Not on OOB, as the case failure was wrong. 2. Massive overpressure (duh). 3. Bore is clear of obstructions. 4. Bolt lugs are intact, for the most part. So it appears the case chambered okay and ignited okay. Then things go bad. So, possible problems include: 1. The case was loaded with much more energetic powder than rifle powders (e.g., pistol powder) 2. Bore was obstructed and the bullet from this cartridge forced the obstruction out, leaving a clear bore. 3. Something other than an obstruction caused the bullet not to travel down the barrel In the correct manner. Other kabooms where the wrong powder was used look like this, but absent chemical testing we'll never know for sure. If an obstructed bore was cleared by this bullet, there should be some evidence in the barrel that a borescope might reveal. But I am wondering what might happen if this case had a seriously out of spec bullet, specifically something the about the size of a 5.76mm or even a 6mm (.243) bullet. The bullet shown has a BT, so it would fit into the case mouth during loading. The neck could have been thinned enough to allow chabering, and the protruding bullet would not necessarily have contacted the rifling, keeping the case from seating. But at firing, the bullet has to deform to fit down the bore, and that completely changes the shape of the pressure curve, possibly enough to reach the failure point of the gun. Just an idea to consider. |
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Posted: 10/24/2014 10:38:39 AM EDT
[#14]
Quote HistoryQuoted: I finally got the upper apart and this is the result: http://i60.tinypic.com/2zdw4dh.jpg http://i59.tinypic.com/2iv1wth.jpg http://i62.tinypic.com/2hmlwjm.jpg http://i61.tinypic.com/2j5m4jc.jpg http://i62.tinypic.com/333v0ap.jpg http://i61.tinypic.com/2qs6ip1.jpg http://i57.tinypic.com/2r254p5.jpg http://i61.tinypic.com/fun7td.jpg http://i61.tinypic.com/ejec83.jpg http://i58.tinypic.com/208h3dz.jpg http://i59.tinypic.com/264287q.jpg http://i58.tinypic.com/35ibqsy.jpg http://i60.tinypic.com/2aihtgp.jpg http://i62.tinypic.com/ftk5k8.jpg http://i57.tinypic.com/34zyid1.jpg http://i60.tinypic.com/jiypnp.jpg   . . . . I said GAWT-DAMN ! |
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Posted: 10/24/2014 10:44:51 AM EDT
[#15]
Never mind , I see you have already .  |
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Posted: 10/24/2014 10:56:44 AM EDT
[#16]
 at all the OOB bullshit.
Anyone catch the number stamped on the bolt face? |
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Posted: 10/24/2014 11:00:49 AM EDT
[#17]
Mother of god
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Posted: 10/24/2014 11:02:58 AM EDT
[#18]
Quote HistoryQuoted: That is what I said. The primers cannot leave intact as they are manufactured on site. Yes, CCI makes a military primer in Lewiston but that is not the source for LC primers, it is part of the non GOCO ammunition manufacturing lines like Olin's Q line (Q3131 being a M-193 alternate source). Quote HistoryQuoted: Quoted: Quoted: Lake City is the brass but I would bet a grand it was not assembled and packaged in Lake City Army Ammunition Plant. That is a GOCO plant, government owned contractor operated. All produced ammo is property of the US government and cannot be sold or diverted. Only components that are non explosive can be salvaged, primers must be rendered inert. As much as I hate to argue with Keith J, that statement is not correct. Explosive components can be salvaged and re-sold, I work for an explosives recycling and waste management company and Lake City/ATK send us stuff quite often. As long as the ammunition does not stay intact, so you pull the bullet and powder, and sell it as component parts, its OK. Pull down propellants used to be quite common in reloading circles. |
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Posted: 10/24/2014 11:40:48 AM EDT
[#19]
It is my recollection that the bolt was still lockexin the extension when OP received the rifle.
How do you have an OOB when the bolt is locked? Bad round. We will probably never know if it was a bad case or wrong powder. But it would help narrow it down if we could read the case head. Is there enough left to read? |
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Posted: 10/24/2014 11:49:02 AM EDT
[#20]
Quote HistoryQuoted: 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... The rifling and barrel look perfect. Of course, that's just by eyeballing it. |
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Posted: 10/24/2014 12:01:39 PM EDT
[#21]
Well we know for a fact the margin of safety designed into the gun was adequate, because while the parts broke, it didn't become a grenade.
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Posted: 10/24/2014 12:22:00 PM EDT
[#22]
Quote HistoryQuoted: It is my recollection that the bolt was still lockexin the extension when OP received the rifle. How do you have an OOB when the bolt is locked? Bad round. We will probably never know if it was a bad case or wrong powder. But it would help narrow it down if we could read the case head. Is there enough left to read? "03" and the NATO Cross. Lake City |
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Posted: 10/24/2014 12:26:02 PM EDT
[#23]
Quote HistoryQuoted: at all the OOB bullshit. Anyone catch the number stamped on the bolt face? Just noticed that too... |
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Posted: 10/24/2014 1:20:40 PM EDT
[#24]
I can't really tell from the pics, is that line running from extractor to ejector on the bolt face a crack or cut in by gasses?
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Posted: 10/24/2014 1:36:19 PM EDT
[#25]
Quote HistoryQuoted:
No sign of over pressure? What caused the brass flow into the ejector bore?? Quote HistoryQuoted:
Quoted:
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?? Overpressure did. Significant overpressure. He is incorrect. |
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Posted: 10/24/2014 1:38:02 PM EDT
[#26]
Quote HistoryQuoted:
$15 CH, $35 upper, $79 BCG, reuse same bbl and back in business. I would never reuse that barrel with a barrel extension and chamber that took that much overpressure, even though it bled off rather rapidly via the failure in the case through the extractor. |
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Posted: 10/24/2014 2:18:23 PM EDT
[#27]
Very weird.
ETA: I'm going to say partial detonation. Here's a working theory: Out of spec primer compound throws enough of a VoD shockwave to cause the nitro in the double base powder to at least partially go high order. This results in a gigantic overpressure of short duration enough to deform the case to that extent and blow it out. With the chamber locked up by all that pandemonium, the (overpressure) impulse then gets dumped into the gas system and the carrier is cracked by the huge pulse that moves the carrier back but mechanically fails when it cannot pivot/turn the bolt. A "too much" powder overpressure would in my view have flowed the primer with a "riveting" effect. This was shattered. |
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Posted: 10/24/2014 2:27:02 PM EDT
[#28]
Damn, that is impressive
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Posted: 10/24/2014 2:36:16 PM EDT
[#29]
I got the BCG apart. Here are the pics:
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Posted: 10/24/2014 2:41:29 PM EDT
[#30]
Quote HistoryQuoted: 1387delta- what is this item in the red circle? http://i857.photobucket.com/albums/ab138/le_pew/ftk5k8_b_zps4afc5135.jpg It's a piece of brass. |
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Posted: 10/24/2014 2:42:54 PM EDT
[#31]
Here is another piece. It might be part of the extractor. It is magnetic.
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Posted: 10/24/2014 2:44:35 PM EDT
[#32]
Quote HistoryQuoted:
I got the BCG apart. Here are the pics: http://i62.tinypic.com/10ntljo.jpg http://i59.tinypic.com/2vifi40.jpg http://i59.tinypic.com/ic0isj.jpg http://i61.tinypic.com/paiau.jpg http://i57.tinypic.com/11j50js.jpg http://i61.tinypic.com/33u5nhl.jpg http://i57.tinypic.com/103vf46.jpg http://i61.tinypic.com/2dsij2t.jpg http://i57.tinypic.com/2hn9spe.jpg That answered my question. Holy Crap. |
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Posted: 10/24/2014 2:45:23 PM EDT
[#33]
Look at the extra cleavage plane (second separation) to the right of the crack at the firing pin near the extractor area. I again see detonation style shattering damage. a split through the firing pin hole where it lines up with the ejector and extractor (thin, thin, thin sequence) I have seen before. This is slightly different. That extra crack screams "shattering shock" |
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Posted: 10/24/2014 3:03:48 PM EDT
[#34]
I noticed droplets of brass inside the bolt...
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Posted: 10/24/2014 3:04:14 PM EDT
[#35]
I know you can get kabooms out of large cases partially filled with slow powder, for ex. they warn about not loading down .300 win mags because of either hang fires or detonation. A case as small as a 5.56 though I don't know.
Detonation comes up a lot on the shotgun boards even though the powder co's say detonation with shotgun powders is impossible. I found a report online that summarized some tests done in Germany trying to achieve detonation. They were able to get something like detonation in a .308 case with shotgun powder. IIRC they essentially had to retard the initial burn until most of the powder was smoldered into a gas, then it would all go at once. |
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Posted: 10/24/2014 3:24:50 PM EDT
[#36]
Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby.
Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. |
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Posted: 10/24/2014 3:59:30 PM EDT
[#37]
Quote HistoryQuoted: Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby. Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. |
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Posted: 10/24/2014 4:03:53 PM EDT
[#38]
Quote HistoryQuoted:
Any guesses as to what happened to the back of the cartridge? wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. |
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Posted: 10/24/2014 4:10:52 PM EDT
[#39]
Quote HistoryQuoted:
wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. Quote HistoryQuoted:
Quoted:
Any guesses as to what happened to the back of the cartridge? wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. Yup. Blew out at the unsupported spot. Still not sure why. But it wasn't the guns fault. Something caused that case to go nuclear. That could have been way worse, considering the forces involved. |
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Posted: 10/24/2014 4:13:24 PM EDT
[#40]
Quote HistoryQuoted:
Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby. Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. The pivot pin holes. See if ovaled. Most likely not but boy that was a major KB |
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Posted: 10/24/2014 4:28:46 PM EDT
[#41]
Quote HistoryQuoted: wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. Quote HistoryQuoted: Quoted: Any guesses as to what happened to the back of the cartridge? wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. No barrel obstruction that I know of. No visible evidence of one. If these came from a commercial manufacturer, what are the chances of wrong powder / bullet? Excluding those three issues, what could be another situation that would cause this? |
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Posted: 10/24/2014 4:39:43 PM EDT
[#42]
Quote HistoryQuoted:
No barrel obstruction that I know of. No visible evidence of one. If these came from a commercial manufacturer, what are the chances of wrong powder / bullet? Excluding those three issues, what could be another situation that would cause this? Quote HistoryQuoted:
Quoted:
Quoted:
Any guesses as to what happened to the back of the cartridge? wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. If these came from a commercial manufacturer, what are the chances of wrong powder / bullet? Excluding those three issues, what could be another situation that would cause this? Depends on the manufacturer. Mistakes have happened before. It is incredibly rare though. |
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Posted: 10/24/2014 4:39:49 PM EDT
[#43]
Quote HistoryQuoted:
The pivot pin holes. See if ovaled. Most likely not but boy that was a major KB Quote HistoryQuoted:
Quoted:
Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby. Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. The pivot pin holes. See if ovaled. Most likely not but boy that was a major KB Mag well might be damaged as well. Bowed. |
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Posted: 10/24/2014 4:41:34 PM EDT
[#44]
Quote HistoryQuoted:
All of the upper parts are not going the used again. The lower functions fine with the exception of the bolt release which needs to be replaced. It accepts a mag no problem and the mag release works fine too. Quote HistoryQuoted:
Quoted:
Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby. Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. What you going to do wit the bbl? Why not ot put it on a cheap upper with a cheap bcg and see if it works? |
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Posted: 10/24/2014 4:41:35 PM EDT
[#45]
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. I've been reloading DRMO'ed MG brass for years with absolutely no issues. This includes 7.62 LC brass for my relatively hot precision rifle load (43.4gr varget/Fed210M/Hornady 178gr BTHP). No issues with over 10 loadings before I toss the brass. |
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Posted: 10/24/2014 4:42:26 PM EDT
[#46]
Quote HistoryQuoted: Mag well might be damaged as well. Bowed. Quote HistoryQuoted: Quoted: Quoted: Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby. Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. The pivot pin holes. See if ovaled. Most likely not but boy that was a major KB Mag well might be damaged as well. Bowed. |
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Posted: 10/24/2014 4:45:22 PM EDT
[#47]
Quote HistoryQuoted: What you going to do wit the bbl? Why not ot put it on a cheap upper with a cheap big and see if it works? Quote HistoryQuoted: Quoted: Quoted: Think twice about using the barrel extension again. Force from a spreading bolt head sometimes breaks the extension and receiver ring. While it may appear to be intact it might actually be weakened and not suitable for re-use. As for the barrel (chamber), I'm no metallurgist but if it does fail in the future then you're looking at an external pressure vent that isn't soaked up by the AR design, eg. you'll be fragging yourself and everyone nearby. Hopefully your lower is ok. If so that would be the only part of the rifle I would reuse. What you going to do wit the bbl? Why not ot put it on a cheap upper with a cheap big and see if it works? |
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Posted: 10/24/2014 4:46:03 PM EDT
[#48]
Quote HistoryQuoted: No barrel obstruction that I know of. No visible evidence of one. Quote HistoryQuoted: Quoted: Quoted: Any guesses as to what happened to the back of the cartridge? wrong powder, barrel obstruction, or wrong bullet over the charge, ie an over charge. those pictures say it all. look at the dimple on the cas head. its were brass flowed into the ejector. it blew out at the extractor. No barrel obstruction that I know of. No visible evidence of one. If these came from a commercial manufacturer, what are the chances of wrong powder / bullet? Excluding those three issues, what could be another situation that would cause this? |
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Posted: 10/24/2014 4:47:50 PM EDT
[#49]
Is anyone willing to say this the ammo's fault and provide an explanation for the kaboom?
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Posted: 10/24/2014 5:01:14 PM EDT
[#50]
Quote HistoryQuoted: Is anyone willing to say this the ammo's fault and provide an explanation for the kaboom? Yes. You only encounter this amount of brass flow when chamber pressure reaches 100K-140K PSI. No load provided by any ammo (more precisely, powder) manufacturer should achieve that much pressure. A detonating squib or a detonating normal powder column might be possible, but the manufacturer should assume responsibility in these rare cases. They are the ones who select powders and craft these little mini-nukes. |
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