I've heard of this happening but never seen it... anyone else seen similar?

[sirhrmechanic]

So friend of mine was firing an AR pistol, .300 BLK, suppressed. Selier and Beliot (sp?) factory ammo. All going well until he got a tremendous bang.

Gun is an AR pistol with a short (7.5" or so) barrel and a very short gas tube. Purpose-built for .300 and suppressor.

No fragments and no injury. Just a clearly anomalous round and a jam. No further rounds would feed.

We pulled the barrel off and found this stuck in the throat. First thought was that it was part of the casing.... but it's the bullet, which had stuck in the throat/forcing cone and the 'core' had blown out the front of the barrel.

We removed the jacket using a tap lightly threaded in and then pulled out with a small slide hammer. There seems to be no damage to the barrel, no roughness or serious erosion. The remains of the bullet mic out to .307"

I don't have the case, but the shooter said that the primer was blown completely out of it. Which seems odd... never seen that. But I don't have it to look at. The case did eject.

Best I can tell, the round was either massively over-pressured? Or the bullet was faulty and failed. The jacket stayed in the throat... and the core was shot up the barrel. Without the case... I can't diagnose any further. Any thoughts from you guys? I am a bit stumped... except to think possible bullet failure and possible overpressure in case???? Suppressors can create some extra pressure/backpressure... but by the time that happened, this event was all done... with a bullet core passing through the baffles with no jacket!

We checked the chamber and throat and all seems good. Rifle is reassembled, chambers fine. No issues. We put a bore scope up the chamber and I don't see any anomalies. He is going to try some test rounds tonite.

Thoughts?

Cheers,

Sirhr

 

[Mike_in_FL]

I've never even heard of something like this happening. The only thing I can imagine is that it must have had the mother of all crimps on that bullet jacket.

 

[spife7980]

Thats the wrong way to make a chamber casting

 

[pmclaine]

Damn what if that happens clear of the throat and you chamber the next one and pull the trigger?

 

[sirhrmechanic]

Damn what if that happens clear of the throat and you chamber the next one and pull the trigger?

 

[pmclaine]

Does the lack of response mean - "Nothing happens"?

 

[sirhrmechanic]

'Claine... I think the answer is a disaster... blown up gun. But we'll be firing some round slowly. Checking results. Making sure problem is not barrel or setup.

Personally, I think it's a defective round. Odd... but who knows. That's why I am asking!

Cheers,

Sirhr

 

[pmclaine]

'Claine... I think the answer is a disaster... blown up gun. But we'll be firing some round slowly. Checking results. Making sure problem is not barrel or setup.

Personally, I think it's a defective round. Odd... but who knows. That's why I am asking!

Cheers,

Sirhr

That was my supposition also - bad day>

Glad you caught it.

 

[Mooncake]

Were the baffles in the can unscathed? I imagine the core of that bullet wasn't very stable when it was passing through.

 

[sirhrmechanic]

Moon... first question I asked. And the baffles and front are just fine! No apparent hits or damage.

Sort of makes sense as the core was probably about .25" diameter... so a bit of room for yaw.

But you asked, IMHO, definitely a 'right' question! And one I should have brought up in the initial post!

Thanks!

Cheers,

Sirhr

 

[.505gibbs]

Looks to me like there was never a core to begin with.

 

[TheGerman]

Yeah, but did you die?

 

[sirhrmechanic]

Looks to me like there was never a core to begin with.

That's an interesting thought... Big boom might not have been an overpressure, but a hollow powder boom... With the suppressor on might have had enough backpressure th make almost a blank round sound... Interesting theory!

Cheers, sirhr

 

[sirhrmechanic]

Yeah, but did you die?

If I do, I will come back as Shankster....

 

[Deleted member 10043]

Ammo. Bullet left case too early causing massive open powder burn off. Then there is the catastrophic jacket separation due to chamber combustion with enough pressure to send the core out the bore leaving the jacket behind stamped into the leade and beyond. You can see the imprint. It is just a different type of squib. Think two-stroke combustion.

 

[hlee]

I have heard that this can happen to projectiles made like FMJs (with an exposed lead base), designed or modified to have an open tip- not Fmj. I’ve never seen it, and thought it something of a myth. Did this bullet have both an open base and an open tip?

 

[elwarpo]

Would be interesting to compare copper wall thickness of this round and an unfired one. Saw this in an FAL years ago (1980s, Canadian Infantry), 2 out of 20 rounds did this. Thin copper in the front of the bullet (open base, lead filled). Not sure if the thin copper allowed the lead to push through or the bullet was slightly oversized creating more pressure (some rounds were slightly oversize, but we did not have other lots to compare). We NSed (marked non serviceable) the whole lot, end of problem.