Ammo Warning
A guy at arfcom bought some cheapy ammo. Then his AR went Kaboom. Pics.
9 Responses to “Ammo Warning”
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July 23rd, 2007 at 11:57 am
That’s quite ugly.
He is lucky he didn’t eat any metal.
July 23rd, 2007 at 1:50 pm
I’ll tell you right now, that wasn’t the ammos fault.
You can’t charge a .223 with enough powder to cause a failure like that from an overcharge.
It’s POSSIBLE that there was a squib load which lodged in the throat of the bore, and caused overpressure when the round behind it ignited; but from the character of the damage I think it’s more likely that this was a severe out of battery fire, and a weak, poorly made upper.
July 23rd, 2007 at 1:55 pm
Chris B., at first, I thought it was a headspace problem but (fyi) other people report the same issue with the same ammo on their ammo board.
July 23rd, 2007 at 5:26 pm
Did he recover the cartridge case ? Out of battery fire ought to be impossible. What does the bolt face look like ?
July 23rd, 2007 at 5:41 pm
Unc,
I’ve examined these pictures pretty closely; and I’m very familiar with the failure modes of the AR latform and it’s ammunition.
YOu can clearly see the initiation point of the failure is in the barrel extension (where the bolt locks into the chamber). If the failure had been caused by a squib, the rubture would have begun in front of the chamber, and most likely would have been STOPPED by the extension. Then the rear of the reciver would have been damaged by the bolt.
In this case, it’s clear the failure initiated at the barrel extension. This indicates either a massive overcharge, or an out of battery ignition.
The only way you can overcharge a .223 case that much is by using pistol powder. While it is conceivable that a factory reman (ultramax are factory remans) was loaded with pistol powder, it is incredibly unlikely. THere was most likely no pistol powder anywhere near the production line this ammo was made on (for safety reasons you dont keep different powders near each other or near the wrong production line. In fact there are ATF regulations against it).
If there was a moderate overcharge, as would be the case using a very fast rifle powder and filling the .223 case completely (to a compresses load state); even presuming that round made it through the line (which is unlikely but possible), the result would have been a case head separation and some damage to the bolt, plus the magazine being blown out of the rifle.
In this case, the damage was far more sever and far more radical.
Also, looking at the pictures of the bolt retail, you can see that the bolt was thrown backwards violently, however the bolt head isn’t sheared off, nor is the barrel extension. This can only indicate that the bolt was unlocked at the moment of failure.
This incident was clearly an out of battery ignition.
Now, as to cause, that would be more speculative. It is possible that soft primers are the culprit… and in fact I would guess that they are a contributing factor. Most likely however is that the home AR builder used a cheaper, heavier, older style firing pin; and when the round had some trouble chambering (either a tight chamber, a dirty chamber, or slightly out of spec ammo) instead of simply failing to chamber and fire as is the appropriate failure mode, the firing pin traveled forward with enough energy to ignite the primer; and an out of battery ignition occurred.
I would wager that if the builder ever checked a round cleared from the chamber without firing, he would note a slight dimoling. THis is common to ARs withthe heavier firing pin, using commercial grade primers. This is why the military, and better manufacturers switched to a lighter firing pin, and now use MUCH harder primers on military 5.56 ammunition.
July 23rd, 2007 at 6:34 pm
Wish you had trackbacks here unc…
Anyway, I’ve posted my full failure analysis here:
Anatomy of a catastrophic failure
July 23rd, 2007 at 8:17 pm
I have trackbacks (at the url) but to prevent spam, the TB requires a link to the post appear.
Thanks for the info. Interesting stuff.
July 24th, 2007 at 2:09 am
I am sure not an expert by any means, (expert=drip under pressure) but with my 1st AR, an SP1 in 1980 I had plenty of chambering problems as I didn’t understand you had to have SB dies. When not full in battery the SP1 just would not fire at all. Also I have fired a Sten that ejected a lot of slam fires and all they did was swell the case at the base. I have a 9mm case that was recently picked up at an indoor firing range for pistol only, and it is definitely a slamfire and the case is intact, but swelled big time at the base. I don’t see any for sure answers. Did the case stay in the chamber? Is the case ruptured? Is the extractor broken? Sorry, but my vision isn’t so good anymore & I don’t remember any mention of those. A case stuck in the chamber & ruptured out close to the base could indicate a sure nuff over pressure. The forward assist is supposed to be for raming a case forward into battery to break open the upper & lower. I am still shooting the SP1 and have never had a problem with slam fire & I have used every different SR primer available. I do not buy other peoples reloads though. I’ve seen too many problems with commercial reloads from companies that cut corners.
July 24th, 2007 at 8:14 am
[…] Chris has a detailed look at the AR-15 Kaboom that I mentioned yesterday. […]