AR-15 blew up! Thoughts?

[79steeler]

Hey guys a buddy of mine was out shooting a brand new AR-15 the other day with brand new factory Remington ammo. First 30 round mag was smooth, then bang, bang, and then rifle blows up. The upper was of unknown make, but either 5.56 or .223, and ammo was brand new Remington .223 ammo. They stated all projectiles had left the barrel, so I don't think this was caused by a blockage. Seems to me the case head just gave way. Would love to hear thoughts on this.

No signifcant injuries, minor cuts on chin and face from p-mag blowing as seen in pics. P-mag still seems functional believe it or not even though its missing some plastic. Upper sustained minor damage, no damage to lower at all. Upper will be thrown out.

 

[WIVigilance]

Damn, glad everyone is okay!

 

[79steeler]

By the way we had to use a punch and a hammer to get the bolt out of the chamber, it was locked up tight. That's why you see some damage to the area with the silver in the above picture.

 

[pmclaine]

Extractor too sharp cutting case.

Heard of something like that occurring in M1/M1A designs.

Doesn't make sense to me though as case head is usually solid brass, not like you are cutting a balloon.


Well Im in for the smart responses now anyways.

 

[dzander]

I'm guessing the headspce was incorrect.

 

[Son of Dorn]

Extractor too sharp cutting case.

Heard of something like that occurring in M1/M1A designs.

Doesn't make sense to me though as case head is usually solid brass, not like you are cutting a balloon.


Well Im in for the smart responses now anyways.

Semi-related, funny you should mention balloons. That's how cases used to be made; the brass was "ballooned" into shape instead of having a thick, solid base. Which did lead to extractors ripping them open sometimes. But that technique hasn't been used in a long time, so maybe just a bad lot of weak ammo?

@79steeler How did the Pmag blow up?

 

[shoot4fun]

Fired out of battery?

 

[ChadL]

Considering the ongoing quality struggles at Remington could it be an issue of an overcharged round?

 

[shoot4fun]

@79steeler How did the Pmag blow up?

I've seen many magazine failures, bot rifle and pistol, do that over the years. All the pressure has to go some direction and it is best when it gets channeled down instead of back in the operator's face.

 

[j-huskey]

Fired out of battery?

No....

 

[Son of Dorn]

I've seen many magazine failures, bot rifle and pistol, do that over the years. All the pressure has to go some direction and it is best when it gets channeled down instead of back in the operator's face.

That's what I thought. Looks like the windows were the weakest points and the pressure popped through them taking the walls with it?

 

[2aBaC̶a̶]

Pics of upper damage? Have you removed the stuck case and looked down the barrel and chamber??

What ammo?

 

[j-huskey]

Fired out of battery?

Look at the flash hole size..... flash hole is way way way oversize. If it was that way when the primer ignited, hello detonation and extreme overpressure.
All the signs are there for that, and it would not be the first rimingtun round to do that.....
We had a lot, in the yellow boxes, once upon a time, and .......
jmhe

 

[j-huskey]

Pics of upper damage? Have you removed the stuck case and looked down the barrel and chamber??

What ammo?

See repost pic below...

They removed the RP case, yes.

 

[nn8734]

Pressure is the proximate cause. Wonder why there was such an over pressure condition occurred, esp after dumping an initial mag trouble free.

perhaps some sort of imperfection or defect in the brass case itself for that round...a priori I’m thinking ammo, but could certainly be wrong lol.

glad no one was seriously hurt

 

[shoot4fun]

Look at the flash hole size..... flash hole is way way way oversize. If it was that way when the primer ignited, hello detonation and extreme overpressure.
All the signs are there for that, and it would not be the first rimingtun round to do that.....
We had a lot, in the yellow boxes, once upon a time, and .......
jmhe

I just couldn't tell for sure from that picture. I own no rifle ammo in a Remington box for many reasons. The last 12 Gauge shells I got with their head stamp are less than desirable for shooting.

 

[MtnCreek]

Has anything been done to the case between the first and last picture (the two showing it in the chamber)?

 

[2aBaC̶a̶]

If the upper is still in good shape other than some scratches why toss it?

Are you tossing the barrel too?

 

[j-huskey]

I just couldn't tell for sure from that picture. I own no rifle ammo in a Remington box for many reasons. The last 12 Gauge shells I got with their head stamp are less than desirable for shooting.

In creating subsonic rifle ammunition, using pistol powders, one method involves opening the flash hole.
There is a very implicit warning in the articles describing what happens when full power loads are reloaded in cases that have oversized flash holes.
Further warns to crush the case mouth with pliers to keep the cases from ever being potentially reloaded full bore again.

That flash hole is visibly oversized, and there is no way to disprove it happening when the fragment blew out or that being the cause of the overpressure, but
Oversize flash hole gets my vote. jmhe

 

[79steeler]

Pic of the upper. Really no damage other than the mag wll cover is bent and split. Once again .223 Remington ammo.

 

[flyer]

I was thinking maybe bullet setback but the feed ramps look very clean, that's probably not it.

Were the marks at the front of the ejection port made by firing or by the chiseling to unlock the bolt?

 

[79steeler]

If the upper is still in good shape other than some scratches why toss it?

Are you tossing the barrel too?

My concern with the upper is that possible the chamber was not perfect and it allowed the brass to blow out because it wasnt tight all the way around. Just being extra cautious. It's not my upper. I will ask owner if he wants barrel. Zero markings on this upper??

 

[x_789]

The upper being unspecified is what has me wondering. When you can buy these cheap uppers now for less then $150 and cheap BCG. Bad things are likley to happen. Bolts and Barrels can be out of spec. Kinda late but you could try a set of go/nogo if you can get bolt apart and remove the trash case head.

 

[Rocketvapor]

It would be interesting to see a borescope view of the bore.
All projectiles are probably clear now. If a squib was forced out or a neck was left behind there should be 'Marks'
Or, it could just be a Remington issue (yea sure).

Sorry to diss your buddy but the words "new AR" and "first 30 rounds" might play a part in this.


I guess the story is still unfolding.
For you guys second guessing this:
Over 30 rounds fired, all OK?
After the mishap the bolt was still locked, case was still in the chamber (most of it anyway).
Bolt did it's job.
Gas blew small parts up.

 

[nn8734]

My concern with the upper is that possible the chamber was not perfect and it allowed the brass to blow out because it wasnt tight all the way around. Just being extra cautious. It's not my upper. I will ask owner if he wants barrel. Zero markings on this upper??

At very minimum, it should be closely inspected by a gunsmith before putting it back into service...unless it’s cheaper to replace. In that case, I’d toss it and go buy another upper.

Also, I would think if it was a chamber issue, you would have experienced problems right away (short chamber, no bolt closure, excessive length - case head sep which looks different than the damage seen in your pics....Otherwise the brass just expands to fill the chamber. Yours looks like pressure spiked and exhausted rearward.

 

[2aBaC̶a̶]

My concern with the upper is that possible the chamber was not perfect and it allowed the brass to blow out because it wasnt tight all the way around. Just being extra cautious. It's not my upper. I will ask owner if he wants barrel. Zero markings on this upper??

If hes going to just toss it, I would take it off your hands. For testing and evaluation purposes of course.

 

[x_789]

do you have any of the cases from before it blew up?

 

[Rocketvapor]

do you have any of the cases from before the it blew up?

Whenever anything goes wrong it's always good to collect as much of the spent brass as possible.

 

[flyer]

I just noticed the dust cover.

That bend probably indicates the amount that the upper and possibly the lower blew out during the malfunction. It's way too much, so far I wouldn't shoot that upper for fear of metal fatigue even if everything else checked out ok. The lower isn't as stressed as an AR upper but if I had a spare lower, if would swap parts and retire it too. Maybe use a "gun buy back" to get some money out of it.

 

[Rocketvapor]

grab a cheap dust cover and bend it out.
Did the upper bend?

My guess is the dust cover was open when it happened.
It ain't now.

 

[smacha538]

@NFAJohn

 

[Uspsa2011]

Finding the first mag worth of spent cases could at least have potential to give you a data point. Id measure the fired cases against unfired to see if any of those seem grossly enlarged. Could help to determine if something chamber wise is out of spec.

 

[Badfinger]

Are you sure all rounds fired left the barrel? Did anyone actually see all the impacts?

 

[Constructor]

Agree rifle did not cause the problem, overcharged round or weak brass and since it blew out in the weakest spot (extractor) I'm betting it was an overcharged round.

 

[flyer]

grab a cheap dust cover and bend it out.
Did the upper bend?

My guess is the dust cover was open when it happened.
It ain't now.

I think you are forgetting the pin, that makes it much harder to bend.

If you look at the dust cover and imagine it in the open position, it got pushed out hard. There wouldn't be enough gas coming out between the upper and lower to do that, the upper moved A LOT. The lower probably moved too.

If it wasn't the malfunction that bent it, someone probably intentionally bent it which makes no sense.

 

[Rocketvapor]

With the bolt remaining locked, case in the chamber AFTER the boom,
case measurements should still indicate a good fit to the chamber.

Take an AR, drop the bolt, look at where the gas would go.
This case let loose just in front of the dust cover.
The Upper did not bend out that far.

Not being an expert,
it's a weak case or a excessive charge (is there room in the case to fit much more powder? ) or mud/bullet/case neck in the bore or a pushed bullet or a heat soaked round.

Post the lot number of the ammo. Might help someone else.

 

[nn8734]

@79steeler - was the upper checked for headspace w/ a go-no gauge set before taking it out to the range?

I mentioned earlier it doesn’t look like the weapon itself was responsible, if it closed on the GO and not on the NO-GO it would rule out the barrel’s headspace as a suspect.

 

[whatsupdoc]

The case head failed, the bolt was in battery.

Possibilities:

1)Bad ammo, overcharged, undercharged or defective case head.
2)Bad barrel, not enough case head support, chamber bevel machined to deep.

You should have picked up some of the fired brass for the post mortem exam.

 

[Rocketvapor]

brass was probably left behind, with the boxes.
Would be interesting to see measurements on this case.
Bet it was blown out to the chamber

 

[2aBaC̶a̶]

@79steeler - was the upper checked for headspace w/ a go-no gauge set before taking it out to the range?

I mentioned earlier it doesn’t look like the weapon itself was responsible, if it closed on the GO and not on the NO-GO it would rule out the barrel’s headspace as a suspect.

Who does this? AR barrels are headspaced at the factory. Even if the headspace was a little over, it wouldnt cause this. Not that it cant happen but this would be my last guess.

 

[nn8734]

Who does this? AR barrels are headspaced at the factory. Even if the headspace was a little over, it wouldnt cause this. Not that it cant happen but this would be my last guess.

Lol, who does what? Check the upper’s chamber with a gauge? I do every time I get a new barrel, upper or rifle. It takes a few minutes at most.

I guess you didn’t read the rest of the post but to reiterate, I don’t suspect the chamber’s head space is the reason it blew up. I think it was the ammo; specifically that one round.

 

[nn8734]

Who does this? AR barrels are headspaced at the factory. Even if the headspace was a little over, it wouldnt cause this. Not that it cant happen but this would be my last guess.

on second thought,

 

[2aBaC̶a̶]

Lol, who does what? Check the upper’s chamber with a gauge? I do every time I get a new barrel, upper or rifle. It takes a few minutes at most.

I guess you didn’t read the rest of the post but to reiterate, I don’t suspect the chamber’s head space is the reason it blew up. I think it was the ammo; specifically that one round.

How many have you checked and how many were bad?

I've honestly never checked an AR barrels headspace other than taking a loose bolt and barrel and loaded round. Im more concerned with min spec. It either chambers or it doesnt.

 

[nn8734]

How many have you checked and how many were bad?

I've honestly never checked an AR barrels headspace other than taking a loose bolt and barrel and loaded round. Im more concerned with min spec. It either chambers or it doesnt.

Don’t keep track but the count doesn’t matter; I check every time because with my luck, the one time I don’t, I’ll go shoot it and something stupid will happen.

Checking with the loaded round is still checking and perfectly fine as long as you know the round itself is dimensionally appropriate.

Factories aren’t completely infallible, shit does slip through from time to time. If it happens to me, id rather know before I assemble and test fire, not after.

 

[flyer]

I don't bother checking 5.56 because I've never found an out of spec 5.56 bolt. I figure the chambers should be sufficiently consistent as well.

One thing is I try not to scrape the bottom of the barrel with my bolts or barrels. That probably helps me avoid headspace issues.

I have several other caliber ARs. Some have matched barrels and bolts, others I have checked and I haven't found an issue yet but there are some wildcats that have oddball bolts that can cause issues. 6.5 Grendle comes to mind.

 

[Jefe's Dope]

5.56 ammo in a .223 chamber.

 

[candyx]

Was it the gases that caused that mag to blow like that ?

 

[j-huskey]

Was it the gases that caused that mag to blow like that ?

Yes

Seen GI mags blown out of m16's b4. Seen floorplates blown off 20rd gi mags. Pmags are much stronger than GI mags.

 

[Rocketvapor]

This will continue to be a guessing game, post count generator, without real information.

 

[Rlandry]

Somebody actually shoots Remington stuff?