Story: friend buys AR from good friend, all I know is stag LH upper on a spikes lower. Came with a PMag full of Winchester ammo. Fires ~10 rounds, then the mag flies out and the bolt is stuck and casing is stuck just out of battery. He take it home and gets it apart, pics below.
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Is the barrel clear?

What does the chamber look like?

Looks like OOB detonation. Maybe last case neck separated and got stuck in the chamber?

Did your buddy load the magazine himself?

Or he got a loaded magazine and trusted what was in it?

What does the whole case look like that came out of the gun?

I'm going over there in a bit to check it out. He's not super familiar with the platform.

Double tap

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I'll get a better one later

Double taps....All day long Bro....

Try and get some really good pics of the upper, the chamber, the blown out case(especially the neck area.).... Whatever you can see.

Use a flashlight.

I'm not an expert by any stretch, but nothing other than the extractor looks damaged. Barrel was clear. Chamber, lugs, bolt lugs etc. look fine. There's a superficial mark in one of the pics on a chamber lug, it wiped clean though

Ammo pics attached too. Looks to be Winchester super X, I have some at home I can compare it with.

He's got some questions that need answered, but he learned a lesson that unknown ammo is no go.

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lets see the case mouth clear, close

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If you need more let me know

There have been reports of over pressure ammo issues lately, otherwise I would suspect they were reloads.

EDIT: Added a link to a thread which might be relevant.
                   Winchester Ammo Kaboom

Well....That sure does look like overpressure.....Now that I think about it...

I have a couple boxes of factory Winchester 55gr soft point. Here is what mine looks like. Bullets fully seated and crimped on mine.
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Something looks WAAAAAYYYYY off with those loaded rounds.

The bullets don't look seated properly or crimped properly.

Fairly confident there was no barrel obstruction because it was being sighted in and all the rounds fired were accounted for.

He learned a lesson about ammo of unknown origin and thankfully wasn't hurt.

Thanks for the replies.

No, it doesn't.  Not even close.  Please explain how this could be an OOB, and explain how an OOB even happens in the AR-15.


I'll give the same response from the last thread:

OOB = unicorn myth that keeps getting regurgitated.  Plus the extractor is clearly blown out which does not happen in an OOB.  

The is classic case failure.

What cause the case failure is either overpressure (most common) or bad brass.

This was clearly overpressure, due to the blown out and pierced primer.  If the brass was the only failure you would not see those.  OOB does not flow brass into the ejector well, nor does it blow out at the extractor like this, that happens with a locked chamber only.  

So we have overpressure.

Overpressure in an otherwise well functioning rifle can be caused by barrel obstruction, wrong caliber ammo (300 BO in a 5.56 chamber), wrong powder, or powder overcharge.  In theory bullet setback as well but that's more theoretical than practical in 5.56 rifle cartridges.

Barrel is not currently obstructed.

If this was 300 BO the barrel would be obstructed.

It is *possible* the barrel was obstructed, and this round being fired cleared both bullets.  This means the previous round would have had to have been a squib, and the shooter would have had to cycle the action manually, or would have heard and felt all the gasses being vented backwards instead of out the muzzle as well.  You are getting into some unicorn farting fairy stuff if you think the bullet stopped in between the gas port and the muzzle, cycled the action, and the second round kaboomed into it.  Even if that did happen this would have not resulted, AND there would be severe barrel damage where the bullets collided.

Wrong powder in a single round of commercially produced ammo doesn't really happen.  (Assuming this is actually Winchester ammo and not someone's reloads using Winchester cases.

It's also possible, since the rounds were not inspected prior to loading the magazine by the shooter, that this ammo had a visual defect, like extreme setback, however unlikely.


Most likely candidate = overcharge.  Bad ammo.

After seeing the picture of the loaded rounds I was going to say the same thing.
The seating depth looks off on those rounds. You can see the difference in the cannelure Vs the case mouth. Also, it does not look like they have factory crimps. Look at the picture posted by j3_, those are factory crimps.

I am willing to bet those are probably someone's reloads and who knows what they did.

Agree with everyone saying bad reloads. I have some factory Winchester varmint x and they also have a convincing crimp.

Thanks for all the replies