Holy crap on a cracker!

At least some parts are still salvageable, and you're not horribly injured.

How does the FCG look?

FCG is perfect. The only lower part that I need to replace is the mag latch

One of those shooters checking in.

Glad to hear OP is ok, and holy hell was that a kaboom!

See?

Thank God you're ok, brother.

I used to use "small batch" ammo until I got some (in fairly nice packaging) that felt more like a .44 Mag than .45 ACP hardball out of my 1911.  Dumbass that I am, I didn't stop after the first couple of shots (a quick double-tap).  Third round blew the mag out and cracked the grips.  You can call me "factory ammo boy" ever since then.

MAN! Glad you're OK! That is some bad shit right there!

Brad

Well, the lower is kinda shot.

It is my opinion that the round probably hung slightly on the feedramps or barrel extension (based on the stove-piping you described) , causing the bullet to set back into the casing as it went into battery.  This can cause an extreme spike in pressure (even with proper powder charge), which can and will cause case head separation when loading to 5.56 pressures already, as well as a big kaboom.  I know some here believe a neck crimp is not necessary when reloading, and it may not be when reloading yourself with proper neck tension and/or reloading for a bolt gun, but there is a reason major manufacturers crimp ammo that may be fired in an automatic/semi-automatic.  Now, is this what actually happened?  I don't know...  If it were me, the first thing I would do is select several rounds at random and press the tip of the bullet against a hard surface checking for movement and visually inspect for crimping.  Just my 2 cents, but hey, opinions are like @$$holes, everybody has one and they all stink, lol..  Good luck, hope everything works out for you!!

So you are saying a severe bullet setback will not cause case head separation?  I believe the pressure spike from a bullet setback causes just that kind of case head separation.  Do you think all the big ammo manufacturers would waste the time and money crimping ammo if it were not necessary?  I agree that it could have been pistol powder as well, but that does not explain his stove-piping issue or what looks to be crimp-free reloads.

Bullet setback did not cause this.

Maybe, maybe not, either could cause the pressure required to cause the case head to separate and kaboom the rifle....

And you know this how?  Pressure caused this, are you saying bullet setback does not cause extreme pressure??

WOW - Glad you're OK!  Amazing that you didn't even have to get stitched up...  CLASSIC EXAMPLE OF WHY YOU SHOULD ALWAYS WEAR EYE PROTECTION!!!

LOL at the peeps that are calling 'Bullet setback' as a possible cause of this.

My money's on the ammo being loaded with some surplus H110 recovered from old 30 carbine pull downs.  Hence the loud shots your friend reported.

It's more likely that bullet not setback enough would cause an extreme pressure spike. This was caused by either a casing loaded one too many times or a very fast burning powder. More likely a combo of the two.

This thread might be interesting to some of the "seating depth doesn't matter" folks.
http://www.ar15.com/forums/t_6_42/428271_Seating_Depth_COAL__and_the_Relationship_to_Chamber_Pressure__An_experiment_UPDATE_IN_OP.html
Linky

Kind of reminds me of the kabooms in the eightys of 38 and 357 revolvers using lightweight loads of bullseye.

You still have some of the barrel extension.  You could potentially try to headspace it.  unless it is way way out, I would suspect the ammo.  

I'd bet money that stretched the threads. A LOT.

Jesus, glad you have all your digits

If I had done the mag well grip, I would probably be missing a hand

For the love of God, why the hell would you try to use the barrel or extension after that severe of a failure?  Why not take the chance of saving a few bucks and shoot the same ammo suspected of causing the failure?
The  guy just won the lottery by walking away with scratches!

He's not saying to use it, he's saying check the headspace to see if that was a factor in the kb.

My fault. I see that now.

I really don't care what any of the rest of you think or say here about bullet setback not causing kabooms, though I think you're sending a bad/incorrect message to anyone here who may be a novice reloader/shooter or may become one in the future....  I was at the range about 7 years ago and a younger guy showed up with a new AR and a box of re-manufactured ammo,  he fired 7-10 rounds and had a stovepipe, bullet was slightly canted when I helped him clear it (he was unfamiliar with the platform, and I was near him with my AR's).  Another 5 rounds same thing happened again, this time the bullet was not only canted but shoved back about 3/16" past the cannelure, helped the guy clear the round and he proceeded firing again.  10 - 15 more rounds another stovepipe, this time the bullet tip barely protruded from the casing, maybe 1/4" if that.  I asked him to see a few of his fresh rounds,  I pushed the bullet tip into the bench, first 6 or 7 were fine, next one shoved in to where the casing was 1/8" from the bench.  I advised him not to shoot anymore of that ammo and offered him two boxes of Winchester white box 5.56 that I had (it was cheaper then, and I try to encourage young shooters when possible), he accepted and loaded them in two mags of twenty.  Every round of the factory ammo loaded and fired without a hitch, no issues whatsoever.   Guy was then amped up, like we probably all get after a few mag dumps, and wanted to shoot up some more of his re-mans (I again advised against it, but left it alone, none my damned business kind of deal).   He reloaded the two mags, and boom, boom, boom, kabooomm....  Scared the hell out of both of us, he was a little scuffed/scratched up, but otherwise fine (about like the OP of this thread).  The upper and lower were both destroyed (though holding together better than the magnesium), the barrel extension was split top and bottom, case head separated nearly identically to what's shown in OP's pic, BCG split up/ "banana peeled", down to the extractor being blown out.  Now, what are the odd's that one batch of ammo had not only poor neck tension causing setback's and stovepipes, but also a round/rounds loaded with pistol powder?  Nobody will ever convince me that a bullet setback didn't cause the kaboom I witnessed, and others as well..  Did it cause the OP's kaboom?  I don't know, but neither does anyone else here, anything said here is speculation at this point, on my part or yours...  Due to my experience, here are the things I do not do myself for my safety as well as others shooting with or around me:

1.) I never shoot re-manufactured ammo or ammo reloaded by another reloader.
2.) I never shoot ammo in an automatic/semi-automatic that is not crimped (at least slightly).
3.) I never continue to shoot ammo that is stovepiping without checking out several of the rounds first.
4.) I never hold back my opinion when I feel it may help someone else out of a bad situation.

Now, please proceed to flame on... Thanks..

I think all your points and info are very valuable. Thanks for your post!

What If headspace was jacked AND the ammo was bad???

I'd like to see a couple pics of the brass if available.. You may want hang onto a few rounds in case u need to dispute the ammo manufacturer should they claim no wrong doing.

****Update*******

Lucky Gunner and MBI sent me a Fedex label to send them the unused 500 rounds and the gun parts . They also asked for a gunsmith evaluation if I had one and also a quote to replace the gun/parts.

That's possible too.

I can take a pic of the bag with some unused rounds. I guess I could open one of the unused bags and keep a few rounds too.

No problem Doc, you're welcome!  I just get aggravated with some of the holier than thou BS that goes on here sometimes!!!  I joined ARFCOM to expand my knowledge, not to close my mind to others with some knowledge, experience, and common sense.  Some people here tend to think your join date and post count indicate your level of knowledge and experience with AR's and firearms in general, I tend to think those guys are full of shit.  

Good post man. Thanks for sharing. I agree. Bullet setback is a huge problem. It's ridiculous to think something as ridiculous as "it doesn't matter with boat tails." REALLY!? When the projectile is set back to the point where only 1/8" of the tip is above the rim, the boat tail is not enough to make up for that kind of reduction in volume available for gas expansion...not even close. Thanks again for sharing your experience.

Here's a round of M193. I hammered the 55gr bullet into the cartridge as far as it would go, then I pulled it. It to 3 wacks with my bullet puller where my uncrimped reloads take about 6. First thing that will happen, if you fired this cartridge, would be the bullet being pushed into the lands and grooves. Second it would fly the the end of the barrel. It in itself would not blow up your rifle. Many guys reload compressed loads with never an issue. I don't really care what camp you're in but bullet setback was not the issues of this rifles demise. Unknown fast/mixed/pistol/whatever powder and unknown casing details is most likely the issue. Blowing up an AR is not as easy as you may think.

Given the OPs description of event, I do think you are correct with powder type/load, etc. being the issue here. I don't think this event was from bullet set back. That being said, I'd be curious to know what the case pressure would reach if the round you posted a picture of, was fired. Though it only took 3 hits from your bullet puller as opposed to 6, I would imagine that there would be a pretty sharp increase in case pressure, even if only for a very short amount of time. I'm sure the projectile would pass through the bore and exit the muzzle, but it would be interesting to know the peak pressure, and what it would do to the rifles components, even if it did not grenade the thing.

I have investigated a fair few incidents and I do not believe the cause here is either headspace or projectile setback in the case.  While projectile setback certainly that will cause a pressure spike, the damage we are seeing here is much more severe than I have ever seen with that sort of event or improper headspace.  

A heavy charge of fast pistol powder is certainly a good possibility.

Here's another possibility.  I have seen a couple of cases  where the shooter had a an unfired cartridge fail to eject and when the action was closed it attempted to chamber the next round.  The tip of the projectile on the second round struck the primer of the round already in the chamber and both functioned.  That receiver was much more heavily built and it suffered significant damage - though not as bad as that one.  Add in a lightweight magnesium receiver and you could get that sort of damage.  

.

This is a serious question. Have you intentionally fired a bullet that's set back? If not, would you do so while filming it to show us it is harmless?

Once I shoot out this barrel I will do it. I'll mount it in a lead sled and pull the trigger with a string. I have plenty of lowers and uppers I can use if someone wants to send me a used up barrel, I'll do it. Even though I am sure it would be fine I would not intentionally shoot that without some safety precautions.

Gun-show-unknown-shitty-reloaded-ammunition seems to be the common denominator in most of these cases.

Thats the most gun carnage I've seen from a KB!!!

Another thought. When I reload, I check all my loads in a chamber gauge. Every once in a while, I'll get a round that will not chamber. For some reason the neck wasn't pushed back enough. I've had worse ones than what's in the picture below. I highly doubt these reloaded ammunition makers are checking every round. The round doesn't chamber, no bolt lock up, fires out of battery, no supported case head, boom!

Your offer is extremely generous and appreciated. I'll try. Thanks!

I also do a 100% check on a case headspace gage. I use a wilson, what gage is that?

He would have had to manually attempt to chamber the failure round over the stuck (unfired) round, which is not what happened as I am told.  I understand your scenario but do not think that's what happened.

 

EGW. It holds 7 rounds which is nice. I drop them in after I seat my bullet, when I fill it up, I dump them in a box. George Smith claims they are cut with real chamber reamers, whatever that means. It works is all I need to know. I just got done a batch of 600rnds 75gr BTHP's, had 18 that wouldn't go. Pulled the bullets and used different cases. All I know is all my 5.56 reloads have been 100% successful on the range.

Using my 14.5" LW Noveske barrel and NF 1-4x FC-2
PSD headstamp
Trim: 1.750"
Seat: 2.250"
23gr H335
#41's
Hornady 75gr BTHP
No crimp
MV 2540FPS

I can probably tighten up the groups with more magnification but I am happy with the load for shooting steel at 300-500yds.


Back to the regularly scheduled program!

I'd like to take one of those sample rounds of that suspect ammo and chamber check in my EGW tool, pull it apart, weigh the charge, try to identify the powder, etc.

I kept a few rounds. I can send you a couple of them.