Bushmaster not backing up their guns?

wrooster · Sep 17, 2012

dmccarty said:
Is the ammo real Lake City or was it Lake City ammo that was demilled into components and then reassembled at another company? If it was the later, the round is basically a hand load and the round may have been double charged or maybe the bullet compressed the powder. Later, Dan

You can't double charge .223 Rem/5.56mm NATO -- there is not enough space in the case.

Wrooster

wrooster · Sep 17, 2012

PoorPlowboy said:
Quite simply, it fired out of battery. If maintenance was not the cause, it is the ammo's fault. Why ATK/Federal hasn't been notified is a mystery.

The Haymaker said:
Explain how. Please.

PoorPlowboy said:
Yes the hammer can hit the firing pin if the bolt is compressed in the BCG, no matter if it has rotated in the bbl lugs or not. Out of battery happens due to poor maintenance.

The bolt carrier has to move all the way forward in order for the hammer to hit the firing pin. And, if the carrier is all the way forward, the cam pin has rotated the bolt in behind the locking lugs. Hence, there is no way to fire out of battery.

It's geometry. Failure to follow good PM practices has no bearing on this.

Wrooster

greasemonkeyok · Sep 17, 2012

May be this is a stupid question since I don't know AR15 geometry, but could the firing pin freeze up far enough out in the extended position from the bolt that when the bolt propels the shell into the chamber it fires the primer?

In other words the momentum of the bolt, not the hammer, fires the primer? Seems the operator would know if he hadn't pulled the trigger when the round went off.

dusty3030 · Sep 17, 2012

The more I looked at the pictures I keep coming back to the ideas below. Here is why. The bolt is indeed locked into the receiver extension, it held but the gas had to come from somewhere.

Looking at the pics and knowing the AR a little a LOT of gas came out of the bottom to cause the bolt carrier failure. A whole lot. That is troubling where it came from?
A pierced primer on a normal pressure round would not have done it.
A split case on a normal pressure round shouldn't have done it.

My idea for gun is at fault:
Severe issue with the relation of the barrel extnsion to barrel / chamber itself - unsuppoted case head failed - gas followed the feed ramps and kaboom. I find this unlikely.

My idea of ammo problem I think is more likely.
WAY overpressure either due to bad round or barrel obstruction caused the case head to fail, again followed the feed ramps and kaboom. I know you said no squib, but it is possible a jacket separated and stuck in the barrel.

It took a lot of gas coming from where it shouldn't to blow that bolt carrier. I am not surprised by the damage to mag well / magazine, that is the easiest escape route and does protect the shooter in a problem like this.

Has he dropped a rod down the barrel to see where it stops?

dusty3030 · Sep 17, 2012

greasemonkeyok said:
May be this is a stupid question since I don't know AR15 geometry, but could the firing pin freeze up far enough out in the extended position from the bolt that when the bolt propels the shell into the chamber it fires the primer?

In other words the momentum of the bolt, not the hammer, fires the primer?

Only if the tip broke off and stayed in the bolt, then it would slam fire until empty like an open bolt machine gun.

The way I assume it was the rifle blew when the trigger was squeezed and was attempted to be fired normally.

thatguy · Sep 17, 2012

The Haymaker said:
So, doing a little reading on "out of battery firing" (consensus from those that understand the AR=impossible) and found this on Arfcom. Quite funny in regards to this thread:

"Only if you are Maine Cartirdge Company and inspecting an AR15 which blew up from the case head failure of defective factory M855 ammunition- after which you, the company, refuse to back up your product and this user is stuck with a destroyed Bushmaster AR15.

So yes - if you're a lying POS from a basement ammunition company - sure - the AR15 "can fire out of battery".

But I'm not bitter or anything........."

Hahaha!

is this the article you read? it appears to be VERY similar to your friends situation..

My KaBoomed AR15, Update May 2nd

It appears that in his situation it was the ammo.. See post #38 on page 4 for a technical findings from Bushmaster about what they think happened..

for those to lazy, here is the findings part of the letter

+++++++++

A squib round was found in the bore that caused the cartridge case head to fail due to the subsequent pressure in the bore forcing back through the action when the bolt unlocked.

The rear of the lugs on the bolt have impressions on them from the barrel extension showing the the bolt was closed and locked when the cartridge was fired and the excess pressure was produced.

The AR type rifles cannot fire out of battery as the firing pin stop in the bolt carrier does not allow for firing pin protrusion until the bolt is closed and locked on a round.

The only way that a round can fire ouf of battery, which did not occur in this case, is if a primer was faulty, improperly installed or there was a piece of foreign material between the bolt and the primer setting it off.

+++++++++++++++++

brian