So... I built my first EBR, a Doublestar A2 20" HB AR just before Christmas last year, a little present to myself. I love the thing! I've posted it here before, but just for grins, here it is again.
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Shoots great, love it to death. However, ammo has become a problem recently, and I'm trying to keep a little stockpile of high quality SHTF ammo, so I've been buying cheaper stuff when available.  I don't normally go to Dick's, but Academy, Wally, and even my closest local shop were all out of 223.  Lo and behold, Dick's has 150rd boxes of Ultramax remanufactured 223 for $40 each. I buy all they have (3 boxes).

I had shot maybe one whole box of the stuff since I bought it a few months ago. I went to the range this past Tuesday with a new friend of mine who used to be in the Navy and loves anything even semi military related, so I brought the AR to shoot. First mag goes great, I let him shoot the second mag, and I'm practicing double taps with the third mag when

BOOM! hock.gif his
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Needless to say, that's an ixnay on at-thay ifle-ray.  For those of you who have succumbed to the dollar like I have, please throw out any Ultramax ammo you may have lying around. There was even another guy at the range who said he had the same thing happen to a Kimber he bought the very first time he took it to the range. Granted, Ultramax made it right and got him another gun (and I hope they will for me, too) but is this a normal occurrence?

Tell me what you guys think. Thanks, and don't you go blowing up your favorite gun like happened to me!

damn- you ok?

i've always had a bad feeling about that stuff, now I know why.  do you think it was a double-charge or what?  

please keep us posted on your dealings with ultramax- i hope they'll make it right.

thanks for posting the pics and for the heads-up.

I'm OK. The mag just bruised my stomach a bit when it blew out of the gun. Over at the S&W forum, a military guy who inspects cases like this said it's unlikely that there would be enough powder in a case (if using any of the normal, mostly-filling powders for 223) to cause this, but possibly a lighter load before this one may have had enough power to eject and cycle the gun, but still lodge a bullet in the barrel. Then the next (and normal) round caused this.  I honestly don't remember a lighter recoiling round, and I don't know if the previous bullet hit paper or not as I was shooting from too far away to see the bullet holes until I rolled the target in.

I'll let you know how Ultramax handles it.

I think an oversized round that doesn't allow the bolt to lock causes this.  

ost

If it were a bullet in the pipe, the barrel wold've exploded, not the receiver.  The aluminum receiver doesn't take hold the pressure in, the barrel/chamber/barrel extension/boltface do.  I'd go along with the idea of the bolt not being locked in - thereby subjecting the receiver to the pressures normally kept in front of the bolt.  

I'm sure someone here will let me know that I'm talking out my ass though, but there you have it.

It could still be a powder caused kaboom.

Pistol powder in a .223 case could do it.

KBarret is right, either this was a round loaded with pistol powder (unlikely), or it was an out of battery ignition.

From the pictures it is clear that the failure initiated in the barrel extension; which means the likliehood of a squib induced catastrophic failure is very low.

Because the bolt head and barrel extension are not sheared off, it is also very unlikely that this was a failure caused by a charge of a very fast powder (like a pistol or shotgun powder); and the .223 case doesnt have enough capacity for a max fill charge to do this (generally speaking a max fill overcharge of a very fast rifle powder in .223 will result in a case head separation at worst).

From the damage, the fact that the bolt head wasn't sheared, that the barrel wasn't banana peeled, and that the barrel extension was the clear initiation point, this really can only be an out of battery ignition.

Now, this could be the fault of the ammunition; but I don't think it is, at least not directly. I think you had a sticky round slamfire. The round didn't chamber completely, but the firing pin had enough energy to ignite a slightly softer than normal or more sensitive than normal primer.

I'd be willing to bet that if you had chambered some of this ammo, then cleared the chamber and checked the primers, you would have seen a slight firing pin impression.

This is why military 5.56 is loaded with special very hard, and less sensitive primers; and why full auto (and many semi-auto but not all) AR platform guns have a lightened firing pin.

I'm thinking out of battery ignition as well.

I've seen what pistol powder in an AR can do, Bear Arms in San Louis Obispo that had accidentally been loaded with Red Dot.  Whole thing Grenaded.

That happened to someone over at Tactical Response. He got in contact with the Manufacturer of his rifle and had a little sit down with the Manufacturer of Ultramax ammo. You might want to contact them as well  

I've already posted on midways site about this garbage ammo a few weeks ago. it wouldn't cycle or group worth a crap, sorry for your loss.

I have read on a couple other forums about this happening a couple times before.

one of the guys took pics and sent them to the ammo maker and the gun was

replaced. i would certainly send them some pics in a certified letter to the ammo

maker.