The magazine exploded out of my AR!!

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nwilliams

nwilliams

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Dec 10, 2006
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Albuquerque, NM
So i went to the range today and was having a grand time until this happened!

I had a few boxes of old Norninco .223 and wanted to get rid of it. First couple boxes shot fine and then I loaded my last mag with 20 rounds from the last box. The first couple shots went off fine so I decided to just empty the mag as fast as I could. I remember hearing a weird pop as one round went off and then immediately after that as I pulled the trigger on the next round there was a loud bang almost like an explosion (which it ended up being), the mag exploded out of the magwell and the bolt was jammed. On the ground at my feet were the remains of the PMag and before we left the range we found most of what remained of it but never found the spring.

My friend was standing behind me and said that he saw the whole thing happen and said that he saw the mag basically explode out of the magwell on the last shot. My friend picked up a shell casing off the ground and walked over and handed it to me, he said that it was the shell of the second to last round fired, I looked at it and noticed a perfect little hole in the side of it, I'm certain that this was the round that I heard make a strange pop just before firing the last round. My friend noticed it because it didn't fly out the ejection port like all the previous shells did, he said this one just kinda fell out..

The gun was seriously jammed, the bolt wouldn't budge and I suspected a broken shell in chamber. I took the lower off and four of us spend about a half hour trying to force the bolt loose but couldn't. When I got home I used a MN 91/30 cleaning rod down the barrel and some good hard whacks with a hammer before I was able to force the bolt out. When the bolt was removed out fell an empty shell with a piece missing from the bottom, it was stuck under the extractor.

After careful examination the gun itself, the bolt assembly and the bolt carrier seemed to be fine. The extractor is bent and so is the firing pin retaining pin. I'm pretty sure that all I need is a new extractor and everything should be well.

Anyway here are some pics.....

brokenshell2.jpg

brokenshell1.jpg

brokenshell3.jpg
 
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nice... Though, I am not sure I saw what was wrong with the ammo? I couldn't gather anything other than it exploded downward into the magwell.
 
Did you try to pogo your gun before you started with the hammer? I found that cleared as many stuck bolts as a cleaning rod did.

You might not have seen anything wrong with the ammo, even if you did inspect it.
 
nwilliams said:
After careful examination the gun itself, the bolt assembly and the bolt carrier seemed to be fine. The extractor is bent and so is the firing pin retaining pin. I'm pretty sure that all I need is a new extractor and everything should be well.
Click to expand...

:what:

NO, NO, NO!!!

Have the entire gun checked out by a gunsmith who specializes in ARs before you even think about chambering another round in that rifle!

If the pressure was strong enough to do the sort of damage you're talking about, the lugs (on both bolt and barrel extension), the barrel, the gas key, the receiver pins and holes, et cetera ad nauseum could be cracked and/or distorted, too. :eek:

Hopefully, everything will check out fine, but consider yourself lucky you weren't injured!
 
Did you try to pogo your gun before you started with the hammer? I found that cleared as many stuck bolts as a cleaning rod did.

You might not have seen anything wrong with the ammo, even if you did inspect it.
Click to expand...
Yeah, we tried to pogo the hell out of it but it was useless in the end and we gave up.

You're probably right about the ammo thing, I didn't notice anything out of the ordinary about the ammo when I was loading it in the mag.

If the pressure was strong enough to do the sort of damage you're talking about, the lugs (on both bolt and barrel extension), the barrel, the gas key, the receiver pins and holes, et cetera ad nauseum could be cracked and/or distorted, too.
Click to expand...
Good point! Thanks

Do you think I should send the upper back to Daniel Defense to have it looked at properly?
 
I think what I'll do is just take the whole gun back to the shop where I bought it and have them ship it back to Daniel Defense for repair. I'm not going to try and fix it myself even if it is an easy fix. I'd rather have Daniel Defense fix it and test it for me. It's still a very new gun, only a couple months old and I've heard good things about Daniel Defense CS.
 
Looks like you had a high pressure event. From the bulged sidewalls (unless you are firing a Belted .223 :D) to the blown case head.

At one XTC match, two shooters on the same RF relay had blown case heads. The magazines blew out.

Maybe the round with the hole in the sidewall left a bullet in the bore, and the next round became an overpressure event?

I would say the design safety features in the AR saved your face, hands, eyes, etc. Stoner did a good job of protecting the shooter in his design.
 
Greetings,

+1 Dionysusigma

You can have a lot more damage than you think. I am not too much concerned about the lower part of the rifle. But I am concerned about the upper part of the rifle.

Thank you
 
Slamfire's right. You're describing the class "squib" series of events:

1) A "pop" of an underloaded cartridge...possibly only the primer without propellant at all, might have left the bullet stuck in the bore. Weak ejection's another sign of this.

2) The next round causes an overpressure event. In an AR, overpressures tend to vent out the magwell, in addition to whatever other mayhem they cause.

In addition to getting an AR smith to inspect it, I would look for signs of barrel bulge both internally and externally. Pop the handguards off and measure with calipers.
 
I can't understand how that one cartridge case got a perfectly round hole in it. The only time I have ever seen this happen was when a jackleg "gunsmith" drilled a Moison Nagant receiver and went too deep, putting a hole in the chamber.
 
We had a customer send one of our guns back with a very similar problem, only he informed us that the ammo in question was a zip lock bag of reloads from a gun show. His upper had bulged, the barrel extension was completely split, the bottom of the bolt carrier had completely been blown off and out the magwell (into his leg), and the only thing left of the case was the headstamp on the bolt face :what: There was no squib in the barrel so my only guess was that the "reloader" double charged a weakened casing. Know where your ammo comes from! I don't shoot anyone's reloads except mine.
 
Perzactly.

Even though I've heard decent reviews of all different kinds of ammo, the least expensive thing I feed my AR is Federal XM193. Since it's my most expensive weapon, I really, really don't want to take any chances.

Side note: that's the only time I've ever seen a PMAG fail. I'd say that given the circumstances, it did pretty well. :)
 
Did you check the barrel for obstructions? It sounds to me like you had a squib round. The barrel doesn't appear to be split but I am curious if there is a round still trapped in there.

The bolt is done. Possibly the barrel as well.
 
1) A "pop" of an underloaded cartridge...possibly only the primer without propellant at all, might have left the bullet stuck in the bore. Weak ejection's another sign of this.
Click to expand...

Okay, but I would argue that if you had a squib go off you wouln't get extraction at all.
 
Longdayjake, a squib can be more than just a primer only. It could have had enough power to get the round very near the end of the barrel. If this was the case you could would get enough gas pressure for very weak extraction.

Also, why does that one round have a hole in the side??
 
Is that brass cased ammo, or copper washed steel cased? Either way, it looks like a bad lot of ammo with brass that was way too thin. The hole in the side of the case is particularly suggestive of this, as that's not where a simple overpressure would normally vent. That says defective case to me.
 
To get any extraction on the first round you would need the bullet to make it to at least the gas port and I think this would take at least a partial powder charge to be present. Maybe it stopped somewhere between the gas port and muzzle, causing a blockage on the next shot? This failure seems less severe than a full blown KB that appears to typically result from a totally blocked barrel though.

On the other hand it is hard to believe that you would get two catastrophically bad rounds in a row in ammo that was shooting fine up till that point... seems pretty likely that the round with the blown casehead is somehow related to whatever happened on the prior round. Close up pic of the first case?

In any event, I would replace *at least* all the carrier internals (bolt, extractor, FP, cam pin, FP retaining pin), and preferably I would send the upper back to DD or other competent smith for barrel/extension inspection.
 
Please correct me, if I am mistaken:

Assuming a squib round stops between gas port and muzzle, we get weak ejection of the squib casing.

The following round chambers and, when fired, due the blockage of the squib round, immediately pushes gas into the gas port, unlocking the action while powder is still burning- in effect, a delay of zero.

The action unlocks under serious chamber pressure, catastrophically destroying bolt, bolt carrier, magazine and whatever else is subjected to the overpressure that wasn't designed for it.

Because the action has opened and relieved the chamber pressure, the barrel and barrel extension are fine, unlike what would happen with a bolt action, for example.

The second round has enough energy to exit the bore and knock the squib round with it. Neither are recovered.

The gas tube would likely show evidence of the over pressure, as at the same time the gas system is trying to unlock the bolt, the chamber pressure is pushing the case head into the bolt and binding up the locking lugs. At some point the locking lugs fail, the BCG flies back and self destructs. The case ejects under full pressure and ruptures.

Is my supposition reasonable?
 
Just from looking at the pix, here's my SWAG.

Round 1 (with the hole in the side of the case). The round fires, the case fails at the hole, however there is enough pressure to push the bullet out of the bore and just barely enough pressure to unlock the bolt and push it back to the point that it can pick up the next round out of the mag.

But, since the bolt didn't get a full push to completely compress the buffer spring, when the bolt returned it didn't have enough inertia to totally engage the locking lugs, leading to...

Round 2 firing out-of-battery, bulging and rupturing the case as you see it, sending the bullet down the bore and venting the remaining gas through the mag well.

Lots of stress going on and it would be wise to have the whole gun checked out before firing it again.

I don't think that you'll have a ring in the barrel, but neither would I be surprised, especially between the gas port and the muzzle. Also, depending on whether or not a small amount of lockup occurred, I would think that the lugs on the bolt and in the barrel extension might be compromised.

Glad you're ok!
 
I Knew those cheap plastic mags were no good! By shooting these new-fangled P-mags you are obviously in danger! Plastic has no business on a gun. Send them to me So I can dispose of them properly.
 
Couple close-ups of the shells.....

VA27 I think I'm with VA27 on this one, I'm pretty sure it fired out of battery, look at the last shell, it's wider at the base almost like it wasn't fully in the chamber when it went off.

brokenshell4.jpg

brokenshell5.jpg
 
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