LWRC KABOOM!

[kdsd731]

Aren't the Tula SR primers soft for a semi-auto? Is it possible that this was the result of a slam fire slightly out of battery?

This is what I was thinking the most myself.

[JMP]

It looks to me like the issue is the brass. I have seen this happen on ARs before. Check to see if the line where the case broke is at the end of your FL sizing. If a case is repeatedly over-sized with an FL sizer, it squeezes the brass and you get a thin spot around the diameter of the case that's right along where the end of the FL sizer ends. As the AR chamber isn't supported, this is a spot of weakness and can fail. It simply looks like that piece of brass has been sized too many times and the FL weak spot was formed. That's my guess.

[Carsgunsandchics]

I'm kinda interested in the front half of the case. It appears to be quite clean for not being completely chambered. It almost looks like it could of been stuffed into the back of a torn case from a case head separation.

[BajaJames83]

I didn't think about that until now.
That may have been and out of battery slam fire that would explain some of the damage to the carrier too

[bsumoba]

As mentioned in a previous post, look at the case head...it looks like a belted case now. It looks like out of battery ignition which resulted in case head separation. Then, the ejector ripped the already cracked case head during extraction.

It also looks like there is a black ring around the primer and large ejector mark.

If he was running it fast, it could have been a soft primer and a slam fire before the case got all the way into the chamber.

Could also be weak, soft brass, OR this piece of brass was resized down too much, cause case head separation that way.

[fguffey]

Catastrophic Failure of Rifle Due To ?

Catastrophic Failure of Rifle Due To ?.

The case failed. WHY?

I have tested receivers that were sold to me as 'suspect'. All 5 receivers survived. The cases used to test the receivers stopped short of catastrophic failure. the primer pockets opened up, the flash holes expanded, the case heads were crushed, the distance from the top of the cup above the web to the case head shortened, unsupported case head increased.

The case body was locked onto the chamber. Control? I did not want to exceed the case head's ability to contain pressure, I could not afford to select a case head that was brittle, I could not afford to select a case with a thin case head, I could not afford to have a chamber that allowed excessive case head protrusion. The receivers were Muasers, the case head protrusion was .113".

F. Guffey

[fguffey]

Catastrophic Failure of Rifle Due To 'a double charge?'

Catastrophic Failure of Rifle Due To ?

http://thefiringline.com/forums/showthread.php?t=341348

F. Guffey

[slamfire1]

The belted magnum appearance of the case head is positive proof of excessive pressure.

I have no idea the mechanism these were fired in, but the case heads have certainly expanded!



I have got to locate the case I found at the range, had been fired in a Rem 700. The case head had expanded so much it looked like a belted magnum. A positive comment on the original Rem 700, the bolt face completely surrounds the case head and the bolt nose flange is encircled by the barrel. Overpressure conditions in a Rem 700 will swell up the case head to completely fill this area, but because the case head is supported in 360 degree circle, the case head will rupture only due to flaws, or ungodly pressures that blow the receiver ring, or turn the brass into a liquid.

[LynnJr]

Looks like bad brass. If you look at the pictures it appears to be a casehead separation was going to happen and the unsupported case simply snapped off.
If the loads were way over pressure you would have noticed it on the first shot.

[hdpauly]

To much powder made the load to hot or an this is what I'm leaning towards, reloaded to many times! Every time a shell gets reloaded it stretches till this happens!

[JagerDog]

I'm sorry for the damage to a great rifle, but I'm even more happy that no bodily harm occured to anyone.

25gr H335 and Benchmark are my go-to loads for bulk reloading of .223. Admittedly, I load them a little longer out and not at the cannelure. I taper crimp as well.

That being said, I will have to guess the following failure modes:

* Round does not seat 100% in the chamber and when fired, the case head is not fully supported and kaboom. There is a noticeable "step" in the case head and it looks like that part of the brass was not in the chamber, much like in some 9mm or 10mm pistols where part of the case head is not fully supported. That case head looks like a belted case now!

* Overpressure, probably due to bullet setback. I see a black ring and a rather larger ejector mark around the primer, which leads me to think overpressure, but your load should be fine.

That's what I'm thinking.

Looks:

A: unsupported (out of battery?)
B: enough pressure to expand primer pocket, flow brass into ejector/plunger, etc. (and break gun).

TMK, simply bad case sees a case failure, but not the other witnesses of excessive pressure.

Out of battery (and/or major setback due to lack of neck tension) could cause poor bullet alignment, skyrocketing pressure.

By any chance have you annealed these cases?

FWIW, more typical case head separation would look like this:

http://riflemansjournal.blogspot.com/2010/05/reloading-case-head-separations.html

Notice failure mode and location.

[kdsd731]

I am leaning towards an out of battery detonation myself. Why it didn't fully chamber I'm not sure yet and why it fired I'm trying to figure out. I know it wasn't over charged. If that had been done on the progressive press it would have made a huge mess by dumping 18 gains of powder on the shell plate and would have been noticed. So that is ruled out to me. Maybe the bullet had set back to spike the pressure? But that is unlikely to me as they are all trimmed after every firing and lightly crimped. And even then, seems like a lot of people don't even crimp the bullets and don't see issues. The number of firings on this case is 2 as far as I know. It was range pick up but it only had one deflector mark on the case when I loaded it. I did not noticed any signs of a weakening brass head when I inspected it. The primer appeared to be set at least flush looking at the pics of it in the chamber still. And he would have had a hard time operating the press if the primer was protruding. But, is there really any way to know for sure?
LWRC does not sell a stripped lower to replace it. They well replace the barrel as standard procedure, replace the bcg and repair this receiver. A replacement complete upper on sale is $1650.

[J-cat]

I thought the design of the bolt does not permit the firing pin to protrude past the breech face if the bolt is not locked into battery. At least that's the case on every AR15 I ever had.

[Old Powderman]

I can tell you want the issue is.

First, allow me to introduce myself. I have almost 40 years of working with AR pattern rifles. I'm currently a certified AR15 LE armorer; I have also had my own gunsmithing business, am an experienced reloader (over 30 years), build my own rifles, and custom swage my own bullets for .223/.224 rifles.

Your kaboom was caused by bullet setback.

I noted that your upper had the feed ramp profile cut into it. Thus, I believe that this is a carbine.

The AR carbine is a violently cycling little beast; it has the tendency to beat up the cartridges as they are fed. Thus, special care must be taken when you load for this cartridge.

IMHO, one of the BEST things that has been marketed for autoloading rifles is the Lee Factory Crimp die. When used properly, you will not deform the bullet, but you will prevent bullet setback. You can use this die on 55 grain loads, but I would consider it a necessity when using the heavier bullets.

[slamfire1]

I thought the design of the bolt does not permit the firing pin to protrude past the breech face if the bolt is not locked into battery. At least that's the case on every AR15 I ever had.

Yes, and that is why AR15 out of battery slamfire reports are exceeding rare. I found one credible one on the web, and I have a Security Guard shooting bud who claims to have seen one. He works at a Federal Facility that requires their Guards to regularly shoot and train. He said with full auto M4's, firing federal gold medal match 223, an out of battery slamfire occurred. Bud is at least a Master class shooter and has been shooting for decades so his observations have credibility. An out of battery slamfire on a AR15 action is most likely to be caused by an extra sensitive primers (they exist) or something on the bolt face. Firing pins however, are retracted behind the bolt face until cam down. I don't see how an AR15 action can have a firing pin initiated out of battery slamfire unless some dimension is out of spec.