Out Of Battery Detonation AR

[Hal]

More pictures please
View attachment 1542157
Brass flowed deep into ejector hole?
Flat primer still below flush with crater?
Extractor pulled the case rim off and case blew out?
Bolt is trash, right? Broken lugs?
Too much gas and over pressure?
Caliber, headstamp, and gas port size?

Extreme high pressure. Look at the amount of brass flow into the ejector hole.

Hal

 

[Rocketvapor]

Was this a Federal case with a thin web and not reloadable?

 

[joshb]

25 caliber bullet slip into the wrong box?
Over pressure from something.

 

[Dimner]

I had a problem like this once but was not as catastrophic. Only my upper and bolt carrier were blown. The bob sled single shot sled and the lower were just fine, so mine was a lot less pressure than this.

Turned out that it was an obstruction in the case. I had been reloading gas checked cast bulled with the brass. During my testing of different loads I ended up disassembling a batch that didn't perform well. During that process I did not catch that one of the gas checks was left behind when the bullet was pulled. Then when resizing, the check was pushed and pinned to the bottom of the inside of the case.

Went to shoot the next batch of test loads and BOOM. Looked very similar to the OPs pic, except that mine was much less pressure thankfully since I was testing lower velocity cast loads. If it was a full power jacketed load, man it would a been bad

That's the long way of saying, your case had an internal obstruction.

Stainless steel pin? Tip of your depriming rod? Flash hole obstruction? Old gas check if you have ever reloaded cast bullets. Something was in that case obstructing and that gas had no where to go but out the back of the case. Glad the shooter was not injured.

 

[tommeboy]

The AR15 has what is called a coned breech face. It is a beveled face to help the round to feed. When a manufacturer cuts this cone too deep bad things can happen. But usually it takes other things that are out of spec to make a catastrophic instance to occur.

You had multiple things go on that caused this. One was the improper cut barrel. Two was a case head the web was too shallow so with the casehead now being unsupported by the chamber. And a possible over loaded cartridge the case blew out from not being supported.

It happens. That is why people talk about tolerance stacking in an AR15 platform. They can be in either direction. You found out what happens when things go in the wrong direction.

Get another barrel that is cut right and this will probably never happen again.

And if anyone ever tells you that a AR15 can fire out of battery don't listen to them because it can't happen. The firing pin is shrouded till the bolt is completely locked into the barrel extension. Only then the pin is protruding enough to let the hammer hit it.

 

[brokeasajoke]

The AR15 has what is called a coned breech face. It is a beveled face to help the round to feed. When a manufacturer cuts this cone too deep bad things can happen. But usually it takes other things that are out of spec to make a catastrophic instance to occur.

You had multiple things go on that caused this. One was the improper cut barrel. Two was a case head the web was too shallow so with the casehead now being unsupported by the chamber. And a possible over loaded cartridge the case blew out from not being supported.

It happens. That is why people talk about tolerance stacking in an AR15 platform. They can be in either direction. You found out what happens when things go in the wrong direction.

Get another barrel that is cut right and this will probably never happen again.

And if anyone ever tells you that a AR15 can fire out of battery don't listen to them because it can't happen. The firing pin is shrouded till the bolt is completely locked into the barrel extension. Only then the pin is protruding enough to let the hammer hit it.

Could you elaborate on the improperly cut barrel? Is the case head unsupported at the feed ramps? Can I drop a round in the chamber and visually check this on say a cheaper budget barrel?

 

[M-61]

brought the destroyed .223 AR to one of the best gunsmiths

How about a pic of this destroyed rifle?

 

[Kracken McGraw]

What’s the little brass disk down below the primer?

 

[46and2]

What’s the little brass disk down below the primer?

That " disc " is brass that extruded into the ejector.

I hate it when we get posts like this with no answers from the OP.

 

[XTR]

What’s the little brass disk down below the primer?

That’s where brass flowed into the ejector.
Doesn’t look OOB to me. Everything I see there looks like an extreme over pressure incident. The commenter above who noted the ring on the case mouth may be onto something… maybe.

I don’t think we’ll solve it from a picture on the web, but something caused that round to have a greatly increased pressure compared to the others. Could have been case too long as noted above, or the bullet got pushed back, or too much powder. If this is part of a lot as stated unlikely that it was the wrong powder. I can’t think of anything else that would increase the pressure that much. (Though I’m surprised nobody has brought up the usual suspect of a carbon ring that seems the be the www answer to all reload woes)

Once upon a time a long time ago I had a 308 with a tight necked chamber. I forgot about that and I am sure I came close to a story to tell shooting M80 ball one afternoon.

 

[whatsupdoc]

Over pressure 100%, there would not be that much brass flow into the ejector hole if
it was out of battery.

"One of the best gunsmiths in town said he thought it might have been something about the round the gun didn't like"

Now that is is funny, that something was the 80,000 pressure the breach experienced
so yea the gun did not like it.

 

[Kracken McGraw]

That’s where brass flowed into the ejector.

Wow that’s crazy!

 

[Walt Schmidlin]

WAG, the 51st fired round may not have been the 51st round reloaded, could have been the 1st reloaded. A previous posted comment indicated a different powder was in his auto powder dispenser, wonder if was a similar solution, maybe 4-5 gas of overlooked pistol powder?

 

[LVLAaron]

I dont think that has anything to do with the gun....

 

[drop_point]

OP, this is not out of battery. Impossible. This was over-pressure caused by either an obstruction or ammunition.

Almost looks like what you'd expect if the wrong powder were used.

 

[ebb]

This topic seems to be way more important to us than the OP, His last visit was the same time stamp as the post.

 

[drop_point]

First time in fifty years of shooting, most times every week.

I in no way mean to offend you, but could your eyes or memory be starting to slip while you're at the reloading bench?

 

[6BRA]

Powder trickler cleared of Bullseye before you started reloading these?

 

[Rocketvapor]

If it was me, I'd be using my Hornady Bullet Puller on 49 reloaded rounds.
Checking for loose bullets, charge weight, and web thickness.

 

[M-61]

“One of the best gunsmiths in town said he thought it might have been something about the round the gun didn't like"

A really definitive statement.