Out Of Battery Detonation AR

[brokeasajoke]

If some one could explain (again my ignorance showing) how is a hard jam and primer pushing the bullet that much different? If I'm jamming my bullet isn't that kind of making an obstruction? Now I fully understand working up on jam vs not. Would say 1 or 2 grains of powder less on jam worked up create that kind of monstrous pressure if it was jam with 1 or 2 more? I could fully see stuck bolt, ripped extractor, or case head.

 

[writerman]

So here’s a serious question that might actually be the answer.

If you are so meticulous and anal about check and double check, how did you miss the odd headstamp?
Or did you see it and figure, no problem using it?

Yes, 300 blackout will often chamber in a 223/556 chamber. An internet search will bring up thousands of hits.

That may actually be a question worth pursuing. Where did the oddball come from?

Ha! Ha! Never did I use the word 'perfect.' LOL! Every so often there's a brain fart over here, and there's no accounting for it. Hate that it happens, but it does. Sometimes it's like there's two people here, the one who pays attention to everything, and the one who doesn't. I am just thankful for being blessed that the one who usually wins and stays safe is the one who pays attention. Not all the time, but usually. LOL! What I figured was, that since ALL of my reloads here are ALL mine and I did them all, and I never overload or hotload, that there couldn't be a powder problem. What the problem was, well, it was something, right? Was it me? Yes? Then all I want to know is, what did I do that was not right. Exactly. Hard to determine. The only thing that was obvious to me so far, is that I could have overlooked a case length. That could have combined with several other factors to create the boom. Is that possible? Case too long? Causes the boom? What theories do you have?

 

[Jeff Porter]

Did you ever show a picture of the bore? Was it obstructed or clear?

 

[writerman]

Did you ever show a picture of the bore? Was it obstructed or clear?

No pic, but I examined it and was clear, no marks or indentations, nothing.

 

[dellet]

Ha! Ha! Never did I use the word 'perfect.' LOL! Every so often there's a brain fart over here, and there's no accounting for it. Hate that it happens, but it does. Sometimes it's like there's two people here, the one who pays attention to everything, and the one who doesn't. I am just thankful for being blessed that the one who usually wins and stays safe is the one who pays attention. Not all the time, but usually. LOL! What I figured was, that since ALL of my reloads here are ALL mine and I did them all, and I never overload or hotload, that there couldn't be a powder problem. What the problem was, well, it was something, right? Was it me? Yes? Then all I want to know is, what did I do that was not right. Exactly. Hard to determine. The only thing that was obvious to me so far, is that I could have overlooked a case length. That could have combined with several other factors to create the boom. Is that possible? Case too long? Causes the boom? What theories do you have?

Sorry post probably came across rude compared to what it would have sounded in person.

You just seem like the kind of guy who probably would have caught the odd case and culled it. But maybe you saw it and went ahead and used it.

Honestly a rogue cartridge almost makes the most sense.

As I stated before I don’t think the powder you used would be able to create the problem on its own. Running numbers in Quickload to get into the danger zone I plugged in numbers to simulate a 10% higher burn rate assuming a hot lot of powder, then added 10,000 pound to start pressure to simulate a ridiculous jam on the bullet in case it popped out while chambering. I think predicted pressure was around 82,000 psi. Really not much over a high end proof load of 78,5000 psi.

To get the pressure needed to cause the damage you had probably would require a powder change.


The other option is an obstructed bore, or possibly loose throat.
A loose throat acts like a restriction. Picture it as a progressive caliber barrel. What kind of pressure spike do you think you would get if 2” down the barrel it dropped from .224 to .204. A defective barrel can easily go from safe to sorry in 50 rounds.

Checking for a loose spot in the bore would also be high on my list of things to check.

I’ve listed a number of other things I would check, you may never really know for sure. But adding some new things to check will also cut down on it happening again.

 

[rockhound78]

Just glad you weren't severely injured!!!

 

[FrankG]

Is that even possible?

Easier than what you would think! I agree with Dave it's in 100k range.

When you start hitting 80k psi range AR's start coming a part / have issues.

We had the State Patrol guys come in with a AR they blew up. They said it was Winchester ammo because it had Winchester headstamp on the case. I asked if they had the boxes of ammo that round came in so we can get a hold of Win with the lot number. They said no. They said it was ammo that had been confiscated over time and they just throw it in a 5 gallon bucket and when they go practice they use the bucket ammo. I said don't do that! Now you don't know if it was a reload and what it was loaded with etc...so can't pin it on Winchester just because of the headstamp on the case. That guns case head completely ripped off from the case body and we had to dig the case head out of the bolt head.

Had a couple of different customers blow up bolt guns. One for sure had a partial charge of pistol powder in the case from changing over from doing pistol ammo. Whole gun came apart. Another shooter blew up a rifle in 7 mag. Same thing had some pistol powder in it. Pressure was estimated at 130k psi between us and a ammo maker. When the barrel was sent to the metallurgical lab to have it checked out they said the barrel did all it could to contain the pressure. Nothing wrong with the steel etc... and they told us based on tests they ran... the pressure was at 150k psi. Both of these bolt action rifles completely came a part. The one rifle the scope was found a hundred yards down range!

The cool part of this story....neither shooter got hurt other than getting their bell rung!

Later, Frank
Bartlein Barrels

 

[Jon Leary]

Seems to be a common problem with AR 223. Doing a mag dump & a squib is not noticed. Some times the brass ejects. Other times the shooter ejects the squib brass, then fires the next round into the bullet left in the barrel. Can be seen on Youtube. 125,000 PSI does real damage.View attachment 1542908View attachment 1542909


More KABOOM pnotos

That,s what I think. Load didnt go bang and he cycled the action and fed another round thinking the chamber was empty but bullet was left in the barrel from a squib. Just hypothetical but I think that would cause the damage.

 

[JerkyFreak]

Have you inspected the other fired cases yet for defects?

Particularly check for damaged necks and check fired neck diameter. Easy way to check diameter is to try and drop a bullet into the fired case. Also check the fired cases for a primer that has been indented more than the rest.

If you find one where the bullet does not drop in or has a deeper than normal firing pin indentation , those would be good indications of a low pressure load that could have been a squib.

 

[243winxb]

Case too long?

SAAMI drawing shows a chamber that is longer then the maximum case trim length, by .012" (1.772") All chambers seem to have this " safety zone" my term.

The chamber length can be measured by Homemade method
To late for your rifle, sorry.

Sinclair has a case chamber length tool for sale.

I did check a Win M70 30-06 that did kaboom. A friend reloaded ammo for him using range brass. A few of the remaining reloads trim lengths were way to long.
Bullet crimped in the chamber.
High pressure locked action. Bolt could not be opened. Stock split badly. No repair possible.



SAAMI does list Proof Load Pressures at the bottom of rifle drawings.

 

[Rocketvapor]

I use a short and a long case (22 Nosler) and a borescope.

 

[whatsupdoc]

OP you have to come to terms that you may never find the exact cause of your
rifles failure. Only you can possibly find the cause as you manufactured the ammo
and were in control of the rifle while it was being fired.

The forum members can only provide ideas and guidance. No one here can realistically predict what pressures were reached but I believe 5.56 proof loads are at around 77,000 psi and your rifle exceeded that by a considerable margin.

If the lower is still serviceable and you wish to rebuild the rifle then I would STRONGLY recommend that you not use any of the upper parts except for the handguard.
The barrel, gas tube, bolt carrier group upper receiver are all trash and should be destroyed to avoid reuse.

I would suggest you review your reloading procedures and make changes to improve
the quality control of your reloads.

 

[jelenko]

review your reloading procedures

One that comes to me is to ensure that once cases are trimmed, they are physically separated from ones that haven't. All it takes is one case that has grown too long for the chamber to create really high pressure.
If you're already ensuring they are physically separated, cool! It is one of my own fears.

 

[Kracken McGraw]

For my own piece of mind, I’m sure glad my pistol powder has it’s own separate powder measure.

 

[boltfluter]

I think you are on the right track here. The one round that caused the issue , in my opinion, is the one to focus on. The fact that it is a different brand is a huge red flag! More than likely proving that your recent reloads were not the problem. Is there any way to track the history of this reload? For lack of a better statement. I am assuming this oddball case was one of your reloads? A friends reloads? Could it have been a .300 BO? Do you own a. 300 BO? You get the idea. Does any of this jog the memory? I would, at the very least, push a tight fitting patch through the bore and look or feel for a bulge or loose spot. When one bullet drives another out of the bore, assuming it did, there will be a very loose section where contact occured and pressure spiked. Just a few things to ponder. Good luck and keep at it. I think you are close to figuring this out.
Paul

 

[ebb]

My friend with Haileigh FL PD was the department armorer, he cleaned an S&W chiefs special for a lady detective and had it blow up when he test fired it. He sent revolver with split cylinder and cut in two top strap with ammo still in the cylinder to Winchester. The analyzed the ammo, the one that Kaboomed and one other are our cases, our primers, but not our powder, the rest are totally ours. Randy talks to chief and explains what has happened, some of our officers are shooting bigger framed revolvers and are hopping up the ammo. Chief has all officers at shift change come in and shoot up all issued ammo and get reissued. five of the officers refused to shoot up all their ammo. They had to buy the lady a new gun, Randy and his wife a night on the town and clean his armorers room and the range for a year. Randy lost some hair and eyebrows and blistered his face. This was back in the 1980s so Winchester may not have the means to analyze like this anymore but with more lawyers than ever I bet they have increased the size of this section.

 

[ArtinNC]

You can't load a 223AR like you were loading for a Bolt gun , you have to use loading data that is for a AR .

 

[DaveTooley]

Possible very little tension holding the bullet in the case and upon primer ignition, bullet moves into the throat and stops, followed by full powder ignition. Bullets acts as obstruction sending pressures soaring. Pressures reach failure point and bullet exits bore.
Just a thought

Rifle functioned perfectly with the prior round. So no bullet lodged in the throat. I can't tell you how many times I've left powder out of cases over the years and no primer is strong enough to do more than just barely stick a bullet in the throat. Many fall out with a tap of the buttstock on a hard surface. Others just need a gentle nudge with a cleaning rod. At many of the matches I compete in there is a cleaning rod on the line for just this eventuality.

 

[jelenko]

FWIW, I've had ~ 10-20 223 rounds with no powder in them - none moved the bullet enough that I could tell by looking at them. The bottom of the bullet was black with soot from the primer.

 

[DonB]

I replyed very early in this post. I have experienced an OOB detonation, it was not fun. After inspecting things I saw that the primer was crooked and not seated correctly. There was enough primer sitting higher than the case that the bolt ignited it as soon as it hit the high primer. Base of the case was ejected as was much brass and powder residue since the action never closed. Never had a chance to even think about pulling the trigger.
My bolt and carrier were not damaged like yours. Barrel extension also did not show obvious signs of damage. The upper however was not salvageable.

So my question is did this round go off as the bolt was closing or did you actually pull the trigger? If you pulled the trigger I don't see how it could have been OOB.

Your load is certainly on the mild side.