Colt HB match Ka- boom

Beater said:
well, i do see that the bolt failed.
But why?....and even if the bolt was the problem, and all things being equal, how the hell would it split the upper reciever like that?
i still figure that it was an overload, plain and simple
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The damage was caused by 50,000PSI gas going where it's not suppose to go......
DPMS had a rep for bolt's failing for a while, it happens.
 
yes, im not new to the game, i relize that the 5.56 is a very high preasure cartridge.
ether the bolt wasnt tempered properly, or it was an overload....or it was both.
 
Well your picture says it all. The bolt was out of battery. No lugs on the locking collar broke off. The case has hemmoraged as would be expected from an out of battery explosion.
 
To me it looks like the bolt is fully closed in this pic. Is this how it looked right after the incident?
Picture004.jpg


The brass flowed into the ejector... looks like way high pressure to me or would this also happen with an out a battery firing?
Picture046.jpg
 
I think that I'll correct my thoughts a little... looking again I see that the cam is in the vertical possition which means the bolt is unlocked. If it was in this possition when the rifle fired it would be a bad thing but I don't know how the firing pin could have reached the primer with the bolt not rotated into the locked possition.
 
it did not fire out of battery.im pritty sure of that, as the bolt was a ##### to get turned, to get out.
as you pointed out, the brass flowed back into the ejector pin hole quiet a ways. if it was a bad headspace problem or something like that it wouldnt have flowed back like that. im still sayin this is simple , case of an overloaded cartridge
 
If it was out of battery and fired after having fired a few mags, is it possible that a small piece of brass etc somehow got lodged in the F.P. hole?

Anyway, glad to hear that you're alright.
 
From all observations the Rifle in question fired while in battery if the it had fired out of battery due to a high primer the action would not be in lock and the casing at the base would not show flow signs , the case would separate around the web with the remaining portion of the case still in the chamber.


" looking again I see that the cam is in the vertical position which means the bolt is unlocked"
The bolt may have moved back as a result of firing and the case may have had flash over occur this is a condition of result of a low powder charge . what occurs is the powder does not completely cover the primer flash hole as a result the flame front travels over the top of the powder this builds pressure and as the powder continues to burn this raises the pressure to beyond the design limits placed by SAMMI and the manufacturer. These photo's can attest to what I believe that the fired cartridge in question was in battery and as result this event was directly related not over filled but rather was a significantly reduced powder charged filled cartridge with powder. This condition has been duplicated past in labs that were developing sub-sonic 308 and 30-06 ammunition.
 
I think westicle nailed it. That ammo is hot to begin with, with the bullet pushed into the case it would spike pressure considerably.....or powder burning in front and behind the bullet.
I doubt an over charge as I don't think you could get enough 748 or whatever they are using for powder in the case to create that high of pressure.
Completely the wrong ammo for 1/7 twist colts though.
 
Hitzy said:
I think westicle nailed it. That ammo is hot to begin with, with the bullet pushed into the case it would spike pressure considerably.....or powder burning in front and behind the bullet.
I doubt an over charge as I don't think you could get enough 748 or whatever they are using for powder in the case to create that high of pressure.
Completely the wrong ammo for 1/7 twist colts though.
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Obviously this is pure speculation, but I would hedge a bet that this is either incorrectly loaded ammo, or one flawed case, not a bolt failure on its own.

Hitzy's statement 'completely the wrong ammo for 1/7 twist colts' is entirely false. I've fired this stuff though both of mine without incident. and with decent enough accuracy. I find more velocity coming from Israeli & South African surplus, IVI, and GP90 than I ever have with civilian made Winchester ammo.
I would contact Winchester immediately so that they have the opportunity to submit recalls for this stuff.
 
beltfed said:
Obviously this is pure speculation, but I would hedge a bet that this is either incorrectly loaded ammo, or one flawed case, not a bolt failure on its own.

Hitzy's statement 'completely the wrong ammo for 1/7 twist colts' is entirely false. I've fired this stuff though both of mine without incident. and with decent enough accuracy. I find more velocity coming from Israeli & South African surplus, IVI, and GP90 than I ever have with civilian made Winchester ammo.
I would contact Winchester immediately so that they have the opportunity to submit recalls for this stuff.
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I don't like shooting anything without a cannalure and solid crimp in any autoloader. 45g bullet is very light for 1/7 twist is what I meant, as it was designed to shoot long tracers and 62g SS109's. If the 55g & 62g ball you shoot is clocking faster than the 45g varmint bullets then something isn't right.......:rolleyes:
Federal AE 55g/62g ammo is brutal for a weak crimp, you can literally push the bullet into the case with your thumb. I won't shoot that either in my AR. Actually, all I shoot is my reloads now, and I have no fear of any of my AR's KB'ing.....:p
 
ammo is brutal for a weak crimp, you can literally push the bullet into the case with your thumb
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that is exactly what was happening with mine, it seemed that the bullet was not hitiing the feedramp the same as 55 or 62gr and the 45gr varmit stuff would literally push the bullet into the casing. maybe the 45gr is shorter OAL and was not feeding the same ??

or maybe it was because mine was an 11.5" and the bolt speed was too fast.... who knows as I sold the gun. but I will never run winchester 45 gr varmit ammo thru any of my ar15's after my experience with them..... frankly it is 55 or bigger for me, even have some nice 64gr power point winchester for deer hunting / coyote hutning if I ever get around to it.
 
I have 2 boxes of 223 Rem 45grn JHP HV 3600 FPS Lot Numbers USA2232.
I fired them out of my 1-9 twist AR 15 without a problem, I only have 40rds through it.

I tried pushing the bullet down with my thumb and I cannot. Its got a slight crimp on it.

I think this happend.... The Bullet got pushed into the case and created a back pressure blowing it out the back. If it was over charged it would create a pipe bomb and split the barrel and destroy the case. But seeing the case its intact except the ass end.

I say its the ammo.
 
numbers
the number inside the carton is 11VF22
barcode number is 2089221369

numbers on underside of box

carton number FO O31241
CT 532
E1 26131
K7 7303

writen just like that
 
I wouldn't out it past being bad mags. If the mags are gimpy, the rounds can get hung up feeding sometimes and the bullet gets forced back into the case in turn causing dangerous back pressure. I had one cheapo one that was doing this to me that I retired and cannabalized for parts.
 
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