View Full Version : Out of battery kabang.
Apologies in advance, I don't have pictures because they said no copies. I have not handled the parts and pieces.
Case head blew out, in front of case head there is about a 1/8 wide ring of expanded metal around the circumference of the case, to me this indicates how far the case was out of battery when it fired.
Shooter had shot 5 mags, of 8 available, before mishap. When policing brass one piece was found near the shooter's firing point with no primer in the primer pocket. Likely, but not certain it came from shooter's rifle.
Bolt carrier was cracked on the sides and bent slightly downward near the bottom. Remarkably, at least to me the bolt seemed to be intact. The firing pin also appeared to be normal and intact (no measurements provided). The extractor was bent significantly outward and the case head from that area of the case was missing. There was significant flow around the ejector which helped locate the case's orientation. Bore of weapon was clear.
Shooter had shot 5 mags, of 8 available, before mishap. When policing brass one piece was found near the shooter's firing point with no primer in the primer pocket. Likely, but not certain it came from shooter's rifle. I was told FCG function-tested OK and there was no sign of primer in lower.
Any ideas as to what could cause such an outcome?
Out of battery is nearly impossible with an in spec AR. Without the bolt lugs rotated, you don't have the pressure to yield a Kabizzle. These are almost always case failure due to excessive pressure... and this is generally due to an over charge of propellant.
vicious_cb
05-17-18, 18:47
Out of battery is nearly impossible with an in spec AR. Without the bolt lugs rotated, you don't have the pressure to yield a Kabizzle. These are almost always case failure due to excessive pressure... and this is generally due to an over charge of propellant.
Yep, the hammer can't even strike the firing pin until the BCG is in battery. Nor does the firing pin carry enough inertia to ignite a primer on its own.
What kind of ammo was he/she firing? I agree that modern ARs that are built to spec should not fire OOB, but if you're firing junk ammo with soft primers, you could shoot OOB if you suffered a double feed.
Is it possible that debris in the firing pin channel could have caused the pin to stick and protrude from the bolt face and ignited the primer prematurely?
Another thought...how old was the weapon? I vaguely remember that older weapons that were assembled without a cam pin would allow firing without the bolt rotating --which could spell disaster.
Is it possible that debris in the firing pin channel could have caused the pin to stick and protrude from the bolt face and ignited the primer prematurely?
The AR has positive firing pin retraction, so it really can't stick.
Another thought...how old was the weapon? I vaguely remember that older weapons that were assembled without a cam pin would allow firing without the bolt rotating --which could spell disaster.
It's bad juju to assemble and fire any AR without a cam pin.
Out of battery is nearly impossible with an in spec AR. Without the bolt lugs rotated, you don't have the pressure to yield a Kabizzle. These are almost always case failure due to excessive pressure... and this is generally due to an over charge of propellant.
This.
Too much pressure from a wrong powder charge or excessively soft brass.
Out of battery is nearly impossible with an in spec AR. Without the bolt lugs rotated, you don't have the pressure to yield a Kabizzle. These are almost always case failure due to excessive pressure... and this is generally due to an over charge of propellant.
Yep, the hammer can't even strike the firing pin until the BCG is in battery. Nor does the firing pin carry enough inertia to ignite a primer on its own.
That is why I asked, same thoughts.
I'm aware that the firing pin isn't long enough to protrude beyond the bolt face until the bolt carrier and bolt are compressed (for lack of a better term).
Also understand the mechanics of the hammer following the bolt home.
The things than give me pause:
1) The ridge/ring of expanded brass indicates the case expanded to the dimensions of the chamber as it was slightly out of battery, before the case head separated. I'm not describing this very well, think of what happens when you fire a 9mm in a .40 - the case expands to fit the chamber - that's what this looked like except before the case head.
2) I also noticed what I called unusual brass smears on the upper portion of the ring of steel surrounding the bolt face and on the extractor itself - from about 7 to 11 o'clock. These weren't from chambering IMO and indicated to me the round fired before the base had contacted the breech face of the bolt.
I'm wondering if there is any possibility that a primer somehow stuck to the breech face and set off the round being fed as the bolt tried to close.
What kind of ammo was he/she firing? I agree that modern ARs that are built to spec should not fire OOB, but if you're firing junk ammo with soft primers, you could shoot OOB if you suffered a double feed.
This was new ammo fired during an agency training session. However, manufacturing is manufacturing and a touchy primer can happen.
I guess we will never know for sure.
If the barrel the chamber is cut short in the barrel and the barrel extension head spaced to that, there will be more unsupported area of the case. Symptoms include pressure rings around the web and cases expanding enough that the primer will fall out.
I think that Markm is spot on... A "hot" load many years back, I ordered 300 rnds of match load 308 that done many of the listed things in bolt smear of brass on bolthead, primer flow and blown primers then blown out extractor. That ended with a few hours pulling bullets and burning the powder. The loads was consistent on charges but likely to been mixed up on powder. On another batch of 308 had some hot loaded that blown out AR10B target's magazine with blown primers and casehead.
Was this a proven gun ? Someone suggested barrel out of specs is the reason I asked . you stated you found another case you think was from the same gun with missing primer so why would it not be possible for a primer or peace of one to ride with the bolt and cause an out of battery ?
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HelloLarry
05-18-18, 06:59
Apologies in advance, I don't have pictures because they said no copies. I have not handled the parts and pieces.
Case head blew out, in front of case head there is about a 1/8 wide ring of expanded metal around the circumference of the case, to me this indicates how far the case was out of battery when it fired.
Shooter had shot 5 mags, of 8 available, before mishap. When policing brass one piece was found near the shooter's firing point with no primer in the primer pocket. Likely, but not certain it came from shooter's rifle.
Bolt carrier was cracked on the sides and bent slightly downward near the bottom. Remarkably, at least to me the bolt seemed to be intact. The firing pin also appeared to be normal and intact (no measurements provided). The extractor was bent significantly outward and the case head from that area of the case was missing. There was significant flow around the ejector which helped locate the case's orientation. Bore of weapon was clear.
I too believe this was an over pressure round.
The bolt started it's travel, but couldn't keep up with the speed of the pressure wave. This is similar to an OP round I had one time that took apart my rifle. This is a typical failure mode of ARs.
The only thing I see as possibly unusual is that the carrier cracked on the sides. Usually they split top-to-bottom from the cam pin cleaving them.
The kaboom would happen before the gas has a chance to reach the gas port.
When policing brass one piece was found near the shooter's firing point with no primer in the primer pocket.
Any ideas as to what could cause such an outcome?
Missing primers are a sign of excessive pressure. Assuming we are talking about factory ammo here.
You described exactly what I would put in a textbook on case failure due to excessive pressure.
I'm wondering if there is any possibility that a primer somehow stuck to the breech face and set off the round being fed as the bolt tried to close.
If the round were ignited before the lugs locked, there'd be no kaboom. The round might burst, but it wouldn't damage the gun as described. Battery is required to achieve that much pressure.
Here's the case. How did that ridge happen if it was locked into battery?
52018
There is a distance from the bolt face to the chamber wall where the case head and some of the body is not supported by the chamber. My guess is that this distance matches where the bulge is in the photo. Looks like the case was expanding in this unsupported area which would take a ton of pressure to occur, and maybe the brass could be partially to blame as well.
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Just over 1/8" of the case is sticking out of the barrel in the M16 design. A bit higher up the case and the wall thins significantly, this thinner wall is where we would expect to see the case fail if it was not fully chambered. Instead the case failed in the thickest part, but only after enough of the brass flowed out the only place it could. The extractor, right? That is where the case blew out? And there is some unusual brass coloration on the bolt and maybe carrier?
Every time I see a severely overpressure round like that, I am reminded how well the AR handles catastrophic failure, from a shooter standpoint.
Andy
The kaboom would happen before the gas has a chance to reach the gas port.
Is more damage done after the gas hits the port? Otherwise damage might be confined to bolt/barrel?
I imagine the carrier can split on sides where the feed lip cuts are, or perhaps I have seen a picture like that and am just imagining that I imagined it..
What I'm saying is, the kaboom happens before the bolt can start unlocking because unlocking doesn't start until after the bullet has left the barrel.
HelloLarry
05-21-18, 20:38
What I'm saying is, the kaboom happens before the bolt can start unlocking because unlocking doesn't start until after the bullet has left the barrel.
That be true. But man, when that bolt does move! :)
wetidlerjr
05-23-18, 06:59
A "kaboom!" at my club from a few years ago (2012).
52106
A "kaboom!" at my club from a few years ago (2012).
52106Wow! Any idea who made of that grenade?
wetidlerjr
05-23-18, 09:20
Wow! Any idea who made of that grenade?
It was a PSA that I think was loaded with the shooter's reloads although he denied it. He said it was Federal something or other. I never saw him after this happened so I don't know positively what caused it.
Another pic:
52110
I'm with the over pressure as well. I no longer have the pictures or measurements from a 6.5 Grendel and the cases due to an improperly gas ported barrel. (won't say the name but they made them with intent of end user using an adjustable block, which I found out later). If it wasn't for the Lapua brass, I think mine would have done the same as above.
It was a PSA that I think was loaded with the shooter's reloads although he denied it. He said it was Federal something or other. I never saw him after this happened so I don't know positively what caused it.
Another pic:
52110Probably lost his nerve and sold off all his stuff. Not a bad thing. I can't imagine a packed to the gills reload doing that much damage. Impressive, and shows why "representative QI" is no better than none at all.
Not arguing just asking ,Can you really put enough of the RIGHT powder in a AR ??? Case to do that much damage or would it have to be wrong powder or Squibb load ? I've seen too little powder become grenades in pistol calibers .
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HelloLarry
05-24-18, 07:53
Probably lost his nerve and sold off all his stuff. Not a bad thing. I can't imagine a packed to the gills reload doing that much damage. Impressive, and shows why "representative QI" is no better than none at all.
Is that supposed to be a slam on PSA?
That rifle handled it like every other AR.
Or are you referring to the ammo?
Probably lost his nerve and sold off all his stuff. Not a bad thing. I can't imagine a packed to the gills reload doing that much damage. Impressive, and shows why "representative QI" is no better than none at all.
Sometimes folks bo bo on what powder is in the hopper. Here is an article about such a mistake:
http://bulletin.accurateshooter.com/2015/01/what-happens-when-you-load-pistol-powder-in-a-rifle-cartridge/
Not arguing just asking ,Can you really put enough of the RIGHT powder in a AR ??? Case to do that much damage or would it have to be wrong powder or Squibb load ? I've seen too little powder become grenades in pistol calibers .
Very easily depending on the powder. Some slower burning powders can compress without exceeding pressure. But a faster burning powder with a bulk density that doesn't fill the case up can easily go way over pressure.
Anybody not scared by that photo really isn't paying attention...
Very easily depending on the powder. Some slower burning powders can compress without exceeding pressure. But a faster burning powder with a bulk density that doesn't fill the case up can easily go way over pressure.I didn't word that correctly , what I was referring to was what was the odds of that severe of a ka boom with powders normally used ,say 1 grain over max for 2200 or 3220 in a 6.8 not using the wrong powder . I know overload is bad but I know under load can be worse sometimes of course any load with wrong powder is very dangerous .
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Sh!t! Never even thought about more volatile powder. Yeah, LOL! That'll bite back!
Kinda odd how his trigger finger was spared. The rest looks like he finger banged a blender. : owie:
Sh!t! Never even thought about more volatile powder. Yeah, LOL! That'll bite back!
Kinda odd how his trigger finger was spared. The rest looks like he finger banged a blender. : owie:Back in the day our guys slipped in behind the lines and replaced a few rounds in VC ammo dumps with Exploders they even went so far as duplicate the looks of the original powder in case the VC caught on . The VC developed bad flinching problems thinking their gun may be next . For some time the AKs and ammo both were suspected and it worked well until the New York times got ahold of it and tipped off the enemy .
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I****ing media! Those asshats have been anti-American since the beginning.
HelloLarry
05-26-18, 09:13
Kinda odd how his trigger finger was spared. The rest looks like he finger banged a blender. : owie:The AR does a pretty good job of protecting the trigger finger. You'll usually get some soot on it, but the upper is a lot weaker than the lower and most of the pressure will exit from the upper and mag well. Usually the upper is trashed but the lower stays intact.
The AR does a pretty good job of protecting the trigger finger. You'll usually get some soot on it, but the upper is a lot weaker than the lower and most of the pressure will exit from the upper and mag well. Usually the upper is trashed but the lower stays intact.Yeah, you'd think it'd do as well protecting the other three. How can a linear force leapfrog the first finger?
I had a slam fire at a highpower match and had a High Master tell me a slam fire was due to a high primer and was not possible otherwise. He was wrong and I proved it with primed cases dropped in the chamber and bolt released in the standing position. I am unable to remember the primer manufacturer. I switched to CCI military primers and never had a problem after that.
LMT Shooter
05-26-18, 13:17
Sometimes folks bo bo on what powder is in the hopper. Here is an article about such a mistake:
http://bulletin.accurateshooter.com/2015/01/what-happens-when-you-load-pistol-powder-in-a-rifle-cartridge/
Yeah, you'd think it'd do as well protecting the other three. How can a linear force leapfrog the first finger?
Joelski, are you referring to the link in 26Inf's post?
HelloLarry
05-28-18, 17:05
Joelski, are you referring to the link in 26Inf's post?
I'd like to know what he's referring to as well. I didn't see any picture of someone with damage to their trigger hand fingers.
LMT Shooter
05-28-18, 17:37
The link has photos of shredded fingers, but that was from a bolt action kaboom.
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