Kaboom :-\ . 223 pics and video

[adam_mac84]

Last stage of todays (small) 3 gun local match .

Probably 75 rounds deep into a 150 round batch that I had loaded for 223.

24 grains h335 (fills enough of case, cannot be a double charge)
-hopper only used for rifle powder, and was in the middle of the whole box I loaded
OAL 2.240 (crimped at cannelure, light to medium).
CCI primers
OAL checked with calipers following size/deprime, <1.755, chamber checked with Lyman case length headspace gauge
Loaded on Lee Turret Press
Checked with Lyman OAL loaded round chamber checker (the orange one) prior to putting in my ammo box after loading

On my computer, frame by frame, at the detonation, you can see bullet impact in the berm. After pulling bolt, barrel is clear. RO and I heard clean click, confirmed later by the video, thinking less likely squib. Unable to determine if the round that was cleared in FTF malfunction had a bullet in the casing. Too many loaded rounds on ground from people clearing the stage.

Of course, first question is always 'are they reloads'. Yes. But upon inspection by some people more knowledgable, they think possibly some sort of failure to fully go into battery (is not a fancy or $$ upper/bolt, Palmetto State Armory), causing detonation out of battery due to some less than ideal tolerances. Hard to say tho, cause gun has been through ~2k rounds

Was not a slam fire. I pulled the trigger.

PIcs coming from my phone so they aren't huge

Any thoughts on diagnosis? I want to obviously be sure things are less likely to happen again (after i beg my wife for the next 12 months to let me get a new rifle

[adam_mac84]

Sent from my iPhone using Tapatalk

[jonp]

Under recoil a bullet that sank into the casing too far due to a lighter than expected crimp causing too much jump.

[lightman]

I don't think that load of 335 would be overpressure enough with a deep seated bullet to do that. I'm thinking Skeettx may be on to something. Glad you were not hurt and hope you find the cause.

[skeettx]

I could not tell in the video, when you recharged the rifle, did you eject a loaded round?
Did the loaded round, now on the ground, have a bullet in it?
Or did the bullet remain in the barrel
Yes, in reading your original posting above.
I guess the only reason you will ever be able to offer is "It was Sunday!!"
Mike

p.s. I deleted the original posting as I wanted to study the video more.

[runfiverun]

I'm seeing too much pressure.
usually a bullet that falls in the case isn't enough to make that happen.
one that was shoved down there by another would.


I have only seen 3 other AR ka-booms, they all have followed a re-charge with the handle.
2 were in 3 gun competition.
1 was in the field.

[johnho]

That's a shame for sure. Two things come to mind. I use H335 behind a 69 but only use 22.5 grns. Hard to tell but that primer looks a bit pushed out but the indent from the firing pin looks normal. Other is maybe a crack at the base of the case you didn't see when reloading. Sure is a mess. Sorry.

[popper]

I'll swag it. Dirty chamber at shoulder and a poor carrier. Seen too many that have very little metal at the mag lip area. OOB fire. Case blew out through the feed ramp, took out extractor & bottom of carrier.

[MyFlatline]

Glad you weren't hurt bad...

[Moleman-]

With the case flowing into the ejector recess I'm going with a gross overpressure. Most likely caused by a squib round that you ejected as skeetex said. YouTube is full of similar videos.

[adam_mac84]

Thanks for the feedback guys!. I am disappointed for sure, but can save for another gun, I only have 2 hands for life, and 1 moneymaker (face). haha.

Forgot to state above, 55grain bullet . FMJ (Berrys)

Question, would the fact that during the detonation, the bullet did hit the berm mean anything? Could it have blown both bullets out if there had been one lodged in there? I can certainly see that as a cause, however, the bullet shouldn't be contacting the lands (2.260 do not impact either)

[skeettx]

Perhaps
And near you, the shooter, I would have looked for a primed/powdered case with no bullet.
Would have been close as it was not gas ejected from the gun.
Too late now, it was Sunday

[adam_mac84]

I did search. That place was right where everyone the whole day had 'unload and show clear'. So there was about 50 empty cases, and a handful of unfired rounds. Searching for the empty PRIMED unstruck case would have been the money find. I did not think about that however

Also, another piece of info on these rounds:
2801 FPS . probably not worth much

[Moleman-]

I've had two instances out of the same batch of some PMC M193 that popped the primer and sent the bullet just into the rifling. Dumped powder everywhere which was a big red flag that there was "some issue". The same thing happen with my buddy only he didn't realize the bullet was still in the barrel. He had tried to load another round but the unburnt powder luckily kept the bolt from closing. He asked me if I had a chamber brush which I did, but also checked the bore which was blocked.

[MaryB]

If it was a squib the barrel would show a bulge, shine a light down it and see if there is a low spot...

[jonp]

If it was a squib the barrel would show a bulge, shine a light down it and see if there is a low spot...

Thats what bothered me about the squib argument unless the squib was right in the throat

[rockrat]

i will take a SWAG. My theory: You had an uncharged round, so when the primer went off it pushed the bullet down in the throat area. You pulled the charging handle, chambering another round. You might have a bulge or you might not if the point of the newly chambered round was resting on the base of the bullet in the throat. Also, possible that when chambering the following round, the bullet in the chambering round hit the base of the bullet in the throat and the bolt didn't lock completely so you also had an OOBD along with pushing 110gr of bullets down the bore. Look on the video and see if maybe you have two bullet impacts on the shot.

Looks like maybe a new upper and bolt/carrier is in the future.

[vzerone]

adam_mac first I'm very happy that you weren't hurt! Okay...out of battery...in battery means that the bolt is close and locked up. Out of battery means it's not locked up and guess you could say open too. Now I guarantee you that if a 50k some round went off with almost all the case in the chamber and the bolt not locked, you'd been severely injured. Pretty rare bird for an AR to fire out of battery. I agree with some of the others that it wasn't a squib load. Like Mary B said there would have been a bulge in the barrel and I discount it stuck in the throat because the round that blew wouldn't have chambered enough to fire it. The case blew at the extractor area and the gas vented down the mag well as it has nowhere to go up to. It's one of those things that will keep you guessing for a long time to come. Who knows, perhaps might have even been a weak case. Most the AR kabooms I've seen the shooter walked away unscathed. Testimonial for the AR design.

Vince

[adam_mac84]

Good discussion guys, again, i appreciate it, and the lack of 'hey *******, you ***** up'. Cause, yes, I know that. Take safety very seriously.

Post mortem analysis of the remaining rounds in that mag. I did find an additional round that with what I would consider moderate pressure, would set all the way back in the case (not finger pressure, nose on the table and pushing in). Got word from a gunsmith (via photos), who also said overpressure. Based on this and the setback that I found on my post-analysis, I am taking my blame 100% and learning from it.

I have to measure the cases that I have (mixed brass), but on visual inspection the suspect (setback manually) case, seems to ahve thinner walls, so my crimping die wouldn't have compressed it as much, leaving the tension up to neck tension, which apparently wasn't enough on this particular cartridge.

Lessons learned.
No more mixed brass for me
Increased frequency of bullet setback (usually do every 25 off the press)
Investigate increasing crimp at cannelure
Investigate/measure plugs in sizing die for internal case mouth diameter.
I will likely take a short hiatus from the reloading game while I get this all figured out

I also would now like to find a cost effective way to measure bullet pull and bullet setback weights... any ideas?

Be safe out there reloaders!!!

[popper]

Look at the thickness of the broken steel at the bottom of the carrier!