AR Sponsor
Posted: 4/12/2016 9:49:38 PM EDT
|
I have done many AR15 autopsies after serious catastrophic failures with either ammunition or the firearm itself. That said, I am hoping to bring in a few outside opinions on this one. I am not one to blame the ammunition or the firearm right away, so any help is appreciated.
I only have pictures of the spent casing, not the firearm itself unfortunately. I will give the best description I can. Firearm was a Black Rain Billet AR15 with a 16" barrel and an AutoSear (legal). The trigger group was a standard mil spec full auto trigger group. Upper had a Black Rain NIB Bolt Carrier Group with unknown round count but had only been fired in this gun, also with an unknown total round count, but likely less than 2,000 rounds given the limit wear I saw on the internals. First picture is of the initial case head rupture. Looks fairly normal for a case head rupture that is usually caused by a brass failure.  " />
Next photo is the headstamp of the casing. I WANT TO BE CLEAR. THIS IS NOT FACTORY LOADED WOLF AMMO AMD THIS INSTANCE SHOULD NOT BE USED TO DRAW ANY CONCLUSIONS ON THE QUALITY STANDARDS OF WOLF. This round was loaded within safe factory specifications and was part of a larger lot of ammunition that has been shot and tested well beyond a shadow of doubt.  " />
Next photo is of the case head from the side opposite of the rupture.  " />
Last photo is of a questionable dent in the side of the casing. I am not convinced that this is of much consequence, but I know with almost certainty that this was not in the casing at the time It was loaded. I am curious if any powder displacement could cause strange pressure deviations of and kind. Thoughts?  " />
The firearm in question had been previously fired 3 time with 90 total rounds approximately 5 minutes before the 4th magazine was inserted, the first round of which is the one you see here. The gun was warm but probably not HOT. Things I know it was Not. -Pistol powder, shooter would be dead or at least missing hands. -Double charge, loading setting is much too controlled, and the powder being used could be filled to capacity and still loaded and fired relatively safely. No pressure signs were evident on any preceding casings at the firing site. All opinions appreciated. I will try to add any pertinent data as I think of it. |
|
Additional details about the upper post KABOOM.
Bolt was not unlocked. The gas cracked the barrel extension and traveler into the receiver. Extractor ripped completely off and the upper receiver split in two from front to back with the crack going almost all the way to the charging handle. |
|
Quoted: Additional details about the upper post KABOOM. Bolt was not unlocked. The gas cracked the barrel extension and traveler into the receiver. Extractor ripped completely off and the upper receiver split in two from front to back with the crack going almost all the way to the charging handle. |
|
Quoted:
Looks like a lug on the bolt dented the case by going over it. Then, when the round was loaded it wasn't able to chamber properly. Rear of the case looks like it formed the hump outside of the chamber. Wild guess. Quoted:
Quoted:
Additional details about the upper post KABOOM. Bolt was not unlocked. The gas cracked the barrel extension and traveler into the receiver. Extractor ripped completely off and the upper receiver split in two from front to back with the crack going almost all the way to the charging handle. Ha, this was going to be my wild guess... |
|
Quoted:
Looks like a lug on the bolt dented the case by going over it. Then, when the round was loaded it wasn't able to chamber properly. Rear of the case looks like it formed the hump outside of the chamber. Wild guess. Quoted:
Quoted:
Additional details about the upper post KABOOM. Bolt was not unlocked. The gas cracked the barrel extension and traveler into the receiver. Extractor ripped completely off and the upper receiver split in two from front to back with the crack going almost all the way to the charging handle. This was the first round in the magazine which was loaded while the bolt was locked open. The bolt never came into contact with the shoulder area of the casing. The barrel has M4 feed ramps and the receiver also has the cuts. |
|
You can see the ejector left a deep impression, and the extractor pulled off a section of the rim opposite side. Primer looks like it began to flow back into the firing pin channel, looks like it separated under high pressure. Wall of that brass looks a little thin to me, maybe too thin to reload.
ETA: dent in case looks like a cleared round from a double feed, possibly accidentally mixed back in with good brass instead of being discarded. |
|
Quoted:
You can see the ejector left a deep impression, and the extractor pulled off a section of the rim opposite side. Primer looks like it began to flow back into the firing pin channel, looks like it separated under high pressure. Wall of that brass looks a little thin to me, maybe too thin to reload. ETA: dent in case looks like a cleared round from a double feed, possibly accidentally mixed back in with good brass instead of being discarded. This was the first time this brass was ever loaded. It was factory new. |
|
Quoted:
This was the first time this brass was ever loaded. It was factory new. Quoted:
Quoted:
You can see the ejector left a deep impression, and the extractor pulled off a section of the rim opposite side. Primer looks like it began to flow back into the firing pin channel, looks like it separated under high pressure. Wall of that brass looks a little thin to me, maybe too thin to reload. ETA: dent in case looks like a cleared round from a double feed, possibly accidentally mixed back in with good brass instead of being discarded. This was the first time this brass was ever loaded. It was factory new. If it was a round which was previously cleared from a malfunction that caused the dent, the dent would have created much higher pressure in the cartridge since it would affect the burn, this would be exacerbated especially if there was any setback on the projectile itself. I have seen rounds with the exact same dent on many occasions.....a guy brought me an upper to inspect a few weeks ago, along with several unfired damaged cartridges, exact same dents as in your photos. His issue was due to failure to extract, and trying to chamber a new round. He asked if he could still shoot those dented rounds after I resolved the issue, I advised him not to. |
|
Quoted:
+1 Quoted:
Quoted:
My guess: slightly OOB. The gas escaping out of the rear somehow caused a pressure difference in the case, making the dent. +1 I initially thought it may have been out of battery as well but the bolt was absolutely locked into the barrel extension and had to be unlocked with vicegrips after cutting the receiver off. I was under the impression that an AR CANT fire out of battery under normal circumstances, and this rifle isn't worn enough for the bolt to normally present any headspace issues. |
|
Quoted:
If it was a round which was previously cleared from a malfunction that caused the dent, the dent would have created much higher pressure in the cartridge since it would affect the burn, this would be exacerbated especially if there was any setback on the projectile itself. I have seen rounds with the exact same dent on many occasions.....a guy brought me an upper to inspect a few weeks ago, along with several unfired damaged cartridges, exact same dents as in your photos. His issue was due to failure to extract, and trying to chamber a new round. He asked if he could still shoot those dented rounds after I resolved the issue, I advised him not to. Quoted:
Quoted:
Quoted:
You can see the ejector left a deep impression, and the extractor pulled off a section of the rim opposite side. Primer looks like it began to flow back into the firing pin channel, looks like it separated under high pressure. Wall of that brass looks a little thin to me, maybe too thin to reload. ETA: dent in case looks like a cleared round from a double feed, possibly accidentally mixed back in with good brass instead of being discarded. This was the first time this brass was ever loaded. It was factory new. If it was a round which was previously cleared from a malfunction that caused the dent, the dent would have created much higher pressure in the cartridge since it would affect the burn, this would be exacerbated especially if there was any setback on the projectile itself. I have seen rounds with the exact same dent on many occasions.....a guy brought me an upper to inspect a few weeks ago, along with several unfired damaged cartridges, exact same dents as in your photos. His issue was due to failure to extract, and trying to chamber a new round. He asked if he could still shoot those dented rounds after I resolved the issue, I advised him not to. +1 Is this another one of the throw from a helicopter, run over with the truck, then burry in the sand tests??? 
Seriously though, everybody ok? No one hurt? |
|
Quoted: My guess: slightly OOB. The gas escaping out of the rear somehow caused a pressure difference in the case, making the dent. The firing pin literally can not protrude from the bolt face until the bolt is FULLY rotated and locked. Even if the firing pin were stuck completely forward, it still could not hit the primer until the bolt was locked.(even a slam fire would have a locked bolt). The only possible way, would be A)a high, soft primer- being set off by the bolt itself. That seems pretty unlikely to ignite a primer. B)leave out the cam pin, the bolt would not lock, but it would still fire. That would be bad C)debris on the bolt face(again, highly unlikely, but possible) |
|
So you're saying the round ruptured, sending the force back.... And to the left.... Back... And to the left.... It seems to me this is some magic bullet. Unless... There was a second bullet.
Barrel obstruction, or out of battery. If it couldn't have been either of those.... Quoted:
Looks like a lug on the bolt dented the case by going over it. Then, when the round was loaded it wasn't able to chamber properly. Rear of the case looks like it formed the hump outside of the chamber. Wild guess. Quoted:
Quoted:
Additional details about the upper post KABOOM. Bolt was not unlocked. The gas cracked the barrel extension and traveler into the receiver. Extractor ripped completely off and the upper receiver split in two from front to back with the crack going almost all the way to the charging handle. X1,000,000 |
|
Quoted:
This was the first round in the magazine which was loaded while the bolt was locked open. The bolt never came into contact with the shoulder area of the casing. The barrel has M4 feed ramps and the receiver also has the cuts. Quoted:
Quoted:
Quoted:
Additional details about the upper post KABOOM. Bolt was not unlocked. The gas cracked the barrel extension and traveler into the receiver. Extractor ripped completely off and the upper receiver split in two from front to back with the crack going almost all the way to the charging handle. This was the first round in the magazine which was loaded while the bolt was locked open. The bolt never came into contact with the shoulder area of the casing. The barrel has M4 feed ramps and the receiver also has the cuts. Obviously a severe overpressure event causing the case rupture as well as the other extreme overpressure signs on the case head. No question about that. Either some sort of powder overcharge or wrong powder (which you say isn't possible), or else either a squib load on the previous shot, or some other kind of barrel obstruction would be the general list of suspects. |
| I know a lot of you are going to shoot this theory down, but when I was an armorer in the Marine Corps we had an event like this. I had been range armorer for a gun shoot and our .50 cals were doing the same thing here. They were tearing the rim from the case, leaving huge dents in the case, severe "over pressure" signs ect. Turns out the cases didn't get the proper heat treatment. The Israeli ammo was issued USMC wide, and because of my findings was subsequentily removed and destroyed out of the USMC ammo lot. The cases looked extremely similar to the ones you posted. Cases not getting the proper heat treatment could be a very real possibility. |
|
I sincerely appreciate everyone's responses here. Today I am going to try and dig a little more into this event, including trying to get access to the video footage of this occurance.
I like the theory that the round was dented through a jam of some kind and then re-inserted into the firearm and caused a pressure spike of catastrophic magnitude. It makes sense in my head. And someone on here is right I think, the rifle couldn't have been out of battery. AR is designed to never fire out of battery, and this was a well maintained, practically new AR15. I think the likelihood of this happening is much too low to be considered. |
|
Quoted:
I sincerely appreciate everyone's responses here. Today I am going to try and dig a little more into this event, including trying to get access to the video footage of this occurance. I like the theory that the round was dented through a jam of some kind and then re-inserted into the firearm and caused a pressure spike of catastrophic magnitude. It makes sense in my head. And someone on here is right I think, the rifle couldn't have been out of battery. AR is designed to never fire out of battery, and this was a well maintained, practically new AR15. I think the likelihood of this happening is much too low to be considered. Kind of unrelated but what kind of lower receiver damage was seen? Any damage to the sear? |
|
Quoted:
I sincerely appreciate everyone's responses here. Today I am going to try and dig a little more into this event, including trying to get access to the video footage of this occurance. I like the theory that the round was dented through a jam of some kind and then re-inserted into the firearm and caused a pressure spike of catastrophic magnitude. It makes sense in my head. And someone on here is right I think, the rifle couldn't have been out of battery. AR is designed to never fire out of battery, and this was a well maintained, practically new AR15. I think the likelihood of this happening is much too low to be considered. I searched an managed to find a photo from an archived thread which demonstrates the damage that may occur with cartridges due to various types of feeding malfunctions. And you can clearly see an extreme amount of bullet setback in the bottom one. 
|
AR Sponsor