so im at the range breaking in my newly built m4gery... crackcrackcrack... crackcrackcrack... BOOOOOM!!! total freaking carnage...

it DETONATED on round # 90... newly refinished magazine guts blew out the bottom, flames coming out the ejection port and bottom of empty magazine... smoke pouring out from between recievers, magazine well, bottom of demolished magazine, and out of all reciever holes... about crapped my pants... my arm hurt, so i tried to look at it while keeping the rifle down range... hair singed, massive welt and powder burns... not good... do i still have all my fingers, im thinking? i drum them on the foregrip to make sure... yup, theyre all there... at this point im thinking the prior round mustve been underpowered and got lodged in the barrel... nope, cleaning rod tells me thats not the case... bolt carrier is jammed partially to the rear... im wondering to myself what the hell happened...  my fiannce runs off to get one of the range guys (good thing SHE wasnt firing the rifle when this happened)... he comes running over and we manage to get the rifle open... both recievers are totally bowed out on the left hand side... bolt is jammed in locking lugs, and bolt carrier is split open in two places on the bottom where it rides on the upper reciever... it is no longer sitting plumb in the upper, is is canted sideways and wedged between the guides in the upper...

SEE PICTURES OF MY NICE, NEW, $1100 PAPERWEIGHT AT:
http://www.fulcrumband.com/fob.htm

i need to know what caused this, and what you guys think i should do to take care of the situation... i did everything right in assembly, function check was flawless, and this rifle was a real tack driver, up until round #90... im assuming the dealer i purchased the upper from will make things right with me (can you say nib m4gery?), since he seemed like a super guy when i ordered, and im going to give him the opportunity to do so... but that doesnt mean that i dont think this is a total crock of shit... i am totally steamed about this...  

dude that suxs...to help get you answer, youll need to furnish more info..mainly on the AMMO you were using.

Correct it sounds like a big ammo problem, that was a over charged round. What ammo were you using?

As stated, info on ammo is needed, as well as manuf. of rifle, who assembled it?

ammo was 55gr, loaded to mil spec (bought at the range, dont remember who mfg was, but i can call the range and ask them tomorrow)... rifle was assembled by me, eagle arms lower, rra upper w/ rra carrier assy, 5.56 chrome lined chamber and barrel... company i bought it from said it was headspaced and ready to fire... guy on the lane next to me had an ar-15 as well, and he ripped through 100 rounds of the range stuff in about 5 minutes, no problem... me, i was shooting 3 round groups... my rifle was hot, but not abnormally so, and recoil from the rounds was comfortable... the range i go to is indoor, and they make you buy their ammo... everything there is a little light in the loafers... if this round was overpowered, i would hate to think what wouldve happend had i been shooting some lake city, or Q3131A... id be missing my left hand right now...

so i dont think its a case of an overpowered round...  i was thinking headspace was off, or the shot was fired out of battery... range guys were inclined to agree...

well now that the ARMS #40 is shit I will buy it from you for the parts for $20 hehe[banana]

YOU are lucky!
I hope that [b]WE[/b] can find out what caused this.


You wouldn't happen to have any lottery numbers you would like to share?


P806

Having seen a number of blow-ups, mostly pistol, on different ranges, I'd immediately suspect the ammo. Most of the time, that turns out to be the culprit.

________________
JayCeeNC

... Wow, good to hear you and yours are safe. Anxious to hear root cause.

My guess is out-of-battery discharge.

The lower is in pretty good shape.  The bowing is minor and it can PROBABLY be bent back to true with some gentle vise pressure and maybe a few judicious strokes with a rubber mallet.

You'll probably never get the bolt carrier out of that upper without cutting the bolt carrier or the the upper apart.   But it would be very instructive to get a look at the bolt face, so somebody needs to pull the barrel..which is probably OK.

Best of all,  with any luck you'll be covered by somebody's warranty.

CJ

Linky made hot.....

I'm no expert, but I had a customer experience a similar failure 10 years ago....  turns out that when you have an extreme, EXTREME, overpressure, the bolt cannot unlock as the carrier has not started rearward yet, SO, The bolt continues to rotate in a locking direction, causing the cam pin to stress & split the carrier! This in turn usually sets off the rounds in the mag, bends/breaks the hammer and the buffer retainer, and in general causes total hell to break loose!! There is usually a great big gouge in the upper just behind the cam pin head recess where the whole unit moved back after the bolt had rotated to the next set of lugs!!! We could never prove the issue because the ammo wasn't recovered, and the fellow who had the rifle wasn't saying too much... we ended up sending the rifle back to the original barrel manufacture, and they repaired the upper at a reduced cost, but both the manufacture and I, after being enlightened, attributed the failure to ammo...  So, depends on which way the carrier was canted, I suspect it way tweaked in an over rotation direction.... I would be all over the "range ammo" guys???   Interesting thread! till...later...GT

Ouch!  When you find out who the manufacturer is, let us know.

Wow, that looks pretty bad!  I'm glad you weren't hurt too bad.  Like others have said, most KB's are due to bad loads.  I don't know how the range loaded their ammo, but all it takes is one bad round to produce the effect that you have experienced.  For example, the loader could have run out of powder and after refilling the powder supply, the operator may have thought the case was empty and run it through the powder loading die again.

Does the barrel look bulged in any way?  Squib load right before round #90?  If the bolt lugs are still engaged, see if you can take a dental pick to try to rotate the bolt to get it out.

Never trust reloaded ammo unless it's from a reputable manufacturer or your own.  I'm sure the range will try to steer you away from thinking that it's an ammo problem because otherwise they might be responsible for your KB.

BTW... Ever since I viewed that weapon, 10 years ago, and the operators glasses... I WILL NEVER SHOOT AN AR, WITHOUT SHOOTING GLASSES! especially since I'm left handed! You really get to wear it all on a deal like that! (How I got as far as I did, I'll never know!) Hope all turn out well .... at least there wasn't any injury.. till...later...GT

Man, that sucks!  Glad you're in one piece...another vote for the ammo.  You *might* wanna get one of them there lawyers hehehe.  

My bet it is an improperly measured powder charge. Over or way under powder load. We had a rifle do the same thing, and after pulling the bullets of the same lot ammo, we found they were undercharged. When the  cartridge layed horizontal, the powder charge did not cover the flash hole at the primer pocket. When the primer shot fire into the shell case, it ignited all the powder at once, hence bringing the peak dwell pressure over the acceptable level. The results looked the same. I always use a powder that fills up most of the case on rifle cartridges or use a wadding to keep from repeating the condition I described.

I don't think I would use that lower again either. I would have whoever is responsible to replace it too. If it was shot out of battery, one would think that the bolt carrier would not be broke in two, and the whole carrier would be driven to the back real fast. I would like to see a picture of the cartridge case or what is left of it. This will tell a lot about head space vrs improperly loaded cartridge. I see a lot of people place their offhand onto the bottom ot the magazine while shooting at long range targets. No doubt the magazine well is the least past of resistance  when a KB happens.  

If you ever get the bolt out of battery, you will find that the bottom of the shell casing has seperated from the rest of the case and that your bolt was BARELY locked when the firing pin fell. Headspace may also be a culprit.

On a good note, be VERY VERY glad that you had FORGED upper and lower receivers. I'd bet cash money that cast parts subjected to those forces would have become shrapnel.

You are a very lucky man.

Amen to that brother, but having personally witnessed a handgun KB and reading stories on this and other forums about other weapons KBing I can safely say that I [b]never[/b] shoot period without some sort of eye protection.

manghu67: Congratulations on still having all of your limbs intact, good luck in getting to the bottom of this!

Hi to all! Last night i disassembled an AR to inspect the bolt carrier group to see if it is possible to have a firing pin strike out of lock up....my conclusion is, Not Possible...  the bolt is designed to full rotate & Lock long before the carrier moves the final distance to allow the firing pin tip to protrude... The round might be going off, but its not the firing pin! till...later...GT

Read Technical note 49 on the Armalite web site.
http://www.armalite.com/

Case head failure, even at normal loads/pressures, can cause this. The high pressure gas flows around the extractor bending it out and locking the bolt in position, cracking the carrier, and blowing out the magazine.

Could be bad brass or overpressure load.

Bushmaster has a similar discription on their web site "Beware the dangers of cheap ammo".

http://www.bushmaster.com/faqnew/content_by_cat.asp?contentid=161&catid=98


If I were you, I would print out both of these articles and go have a talk with the range that sold you the ammo. Seems to me, they owe you a new gun!

10x: ha ha, very funny... funny how the rotting carcass of an ar-15 brings out the equipment vultures (of which i am one)... [:D]

thanks all you guys, for being glad im ok... thats one of the things i love about these forums, everyone cares, and thats cool...

looks like the majority of you think that it was an ammmo issue... the mfg on the ammo wasnt the range, it is ULTRAMAX... theyre a factory, but apparently they reload, because these cases all appear to be lake city...

dont think it was a squib round prior to #90, everything felt normal up until the detonation... bolt still locked up in the lugs, and that bastid is seized up good, so i dont think ill be able to get it appart myself...

not interested in a lawyer, too much litigation already in the gun industry, and that makes it difficult for folks like us to enjoy our "evil black rifles"... i just want a rifle to replace this one...

speaking of which, on a positive note, i did speak with the gentleman i purchased the upper from... he has agreed to send me a brand new rifle, and once he has examined my old one to determine what the cause was, he will send that back to me as well! [banana] i think ill frame it and hang it on my wall... [:D]

as far as safety glasses go, i ALWAYS wear em!  [8)]  doctors can replace lots of things, but they still cant replace an eye... yet...

DevilsAdvocate:  i would NEVER buy anything but forged, especially after this incident...

oldguy: HOLY CRAP!! great articles...

My guess is the brass failed, and you had a major case head seperation. That allowed high pressure gasses come back into the action and blow your gun up. Casehead seperations can be caused by several things but I would bet the brass was reloaded maybe one too many times. If the ammo wasn't reloaded it could be caused by excessive headspace.

I would be asking that range that made you buy their ammo some questions.

Is the ammo the range forced you to use handloaded by them? I'm guessing it is, and if that's the case they owe you a new rifle. Get a lawyer and find out who manufactured the ammo.
I'm betting they are selling you their reloads and one of them had a double charge.

Or not...

In my 22 years of service in the Army and with experience with the M-16 A1, A2, and M-4, I have never seen a weapon do this.  The condition of weapons have been worn out (in basic training) to brand new.  The one constant is the ammo.  It's all brand new and consistant.  By looking at the pictures, I'd say you had a case overpressure.  A detonation out of battery would have exploded all the brass that was not in the chamber at the time.  I would find out what ammo your range is selling, if it is reloaded and who reloaded it!  If they are so picky that you use their ammo, I'd find another place to shoot.  My vote is not the weapon, but rather the ammo.  All it takes is one to do this.  The guy next to you was lucky this time, it could have been him...

DG
OKC, OK

Re double charging a .223 case:

It is impossible to throw a double charge into a 223 case, not enough space.  Overcharge is possible, but it will requircompressing the powder to seat the bullet.

When I was a regular at the funshows, and doing a lot of reloading, I regularly saw new ammo boxes available with unknown names on them.  I bought some for my reloads because they were real cheap, (I have never sold any of my reloads, and never will).

What I suspect is the "reloader" for that range, (employee, friend, guy down the street, etc),
was loading some pistol loads with unique or bullseye, and did not empty his powder measure when he switched to 223 loads.  A full charge of bullseye WILL result in a KB in an AR .

Stay away from those places that only allow you to shoot their off-brand ammo.....

In terms of loading, this is 100% correct.

All I can imagine is a small amount of pistol powder was left in the hopper, and a rifle powder added on top of that. That would imply at least SEVERAL rounds of contaminated ammunition.

so: SAVE THE REMAINING AMMUNTITION from that rotten day. Sure as hell, put it in a red bag, and don't try to shoot it- have the bullets pulled and the powder inspected. If there is pistol powder in there, it's easy to spot. Fine grained.

I would also have the headspace checked.

Glad you are OK. Guns can be replaced.

Finally, if this dealer does come through and replaces your gun, I would like to know who it is. Anyone that stand-up, I want to know about when I make my next purchase.

I would bet it's ammunition, and I'd bet it's contaminated powder.

I agree on the double charge - over would have been a better word. The contamination issue may have even more legs....  

Of course the guys at the range are going to be very sympathetic-- and all the while hoping you won't sue!! Their ammo, right?? Reloads they get from someone, or load themselves in spare time. I'd be finding out who loaded that stuff, even if the guy next to me didn't have any problem. It only takes 1 in 1,000,00 or more, and looks like you got that 1!!

Being a .223 reloader, I agree that a double charge is a virtual impossibility.  The densest powder I know of for .223 is Hodgdon H322, which I use, and it might allow a 50 percent overcharge, but not more than that.   Win 748 is bulky enough that it's hardly even possible to get a dangerous overcharge. A max load is a compressed load.

CJ

I agree with Stinkey Pete:
"Finally, if this dealer does come through and replaces your gun, I would like to know who it is. Anyone that stand-up, I want to know about when I make my next purchase."
That's one heck of a good guy.
As for the reason,I feel like it's ammo too.Another poster mentioned undercharged cases causing a detonation instead of a burn.This has happened many times with light charges of fast burning powder in handguns over the years with no definable cause found.Most blame it on a double charge but many people feel it is detonation.I've never had a kaboom and don't want one either.
I've looked at the photos and I don't see how it could be an out of battery problem as the case would be in shards with almost nothing left.
 Since they are reloads it could be the shoulder was set back by an out of adjustment die,too thick of a neck from repeated firings,case length too long for the same reason,a case head failure from being fired in an oversize chamber in the past (look at an unfired round for a ring around the case near the head),being run through a small base die one time too many has workhardened the brass making it brittle or a high primer could have fired with the bolt almost closed.This is reloading 101 stuff.
The powder charge being mixed with a faster burning powder is a possibilty too.As others have posted,pull some bullets,check for mixed powder,weigh the charge and compare the powder to other proper powders to try to decide what type it is and check some cases for the above problems.Measure the neck OD with the bullets seated to see if they are too thick.With a tight chamber(was it cut to Mil Spec or .223 Rem since it was mil spec brass?)and a thick neck,pressure will skyrocket just like using a bullet that is too large(something else to measure).
Some time ago(it may still be done),the military was selling ammo to be demilled.After you took it apart you could do anything with the components.It's a possibilty that all the components were surplus salvage so the powder may be a little odd looking.I'm not sure which type of powder is being used these days.
Robert.

#1 - to my knowledge, ALL RRA barrels have a .223/5.56mm Wylde chamber, not the M16 chamber

#2 - you state the ammo was milspec, but then talk about Lake City or Q3131 being "hot".  Lake City and Q3131 ARE milspec ammo.

#3 - I think I recall UltraMax ammo being known for it's problems.  Post this to the AMMUNITION forum and check with those more knowledgable.

#4 - sure it was a chromelined barrel?  That's a special order from RRA only recently made available.

(note - 1, 2 & 4 aren't likely culprits)

I had this happen to me a few years ago with a pre-ban Bushmaster.  I had neglected to clean the barrel extension for some time, and build up of carbon in the extension did not allow the bolt to lock up fully.  The result is that when I fired the gun, the bolt was out of battery.  The result was the same: KABOOM!!!  Total shock to everyone on the range.  Blew a perfectly good mag out of the well, completely destroying the mag.  With the concussion, it crumbled the mag stop catch and sent the ACOG scope attached to the handle flying into space.  Completely stripped the bushing and mounting screw from the ACOG's base.  It was quite an impressive blast.  No internal damage to the receiver group surprisingly enough.  Fortunately I had my hearing and eye protection on, but still picked quite a few pieces of brass casing from my body (mostly face).

The day it happened, I was taking my girlfriend to the range for her first time to try her hand at shooting.  Needless to say, after she witnessed this, she has never touched a firearm since.

Was a shock to me, but it happened exactly the way as you described.  Your bolt was out of battery when you pulled the trigger.  Trust me, the results can be worse from what I have heard.

to clear some things up about the ammo: it is ULTRAMAX, lot #287210114... these rounds are jacketed, except for the point, which is lead, and are in lake city cases, so we know they are reloads... they are factory reloads, not reloaded by the range (unless those bastards dig through their trash for empty ultramax boxes and refill them with their own shit reloads)... this range only lets you use soft point ammo, no fmjs... i had some Q3131A that i had brought with me, but they wouldnt let me use it... thats not to say that i couldnt bring my own ammo, provided its soft point (which i will DEFINITELY be doing next time)... i would probably go elsewhere, but thats the only range here...

fight4yourrights: perhaps i was unclear about ammo - when i said lake city and Q3131A were "hot", what i meant was that they are full power military rounds (which is what i would prefer to shoot)... when i stated that the ammo i was using was milspec, perhaps i should have prequalified that with "the retards at the range told me..."  from my experience, if you put the lake city and Q3131A up against the ultramax in a blind test, i would have a difficult time judging which was which... recoil was normal, weapon functioned like a dream until KB, and rounds seemed nice and accurate... as far as specs of the rifle, the dealer told me that it was rra, chrome lined barrel, chrome lined 5.56 chamber...

to all you reloaders: dealer has asked that i purchase five boxes of the same lot # of ultramax, at his expense, along with the remaining ammo and any casings from my range outing and ship it to him so that he can pull bullets and examine powder charges... personally, i know nothing about reloading, so im more than willing to do this... i hope he doesnt try shooting any of to, though... if he does, hes got bigger balls than i do!

gamachinist and stinkypete: the dealer has requested that he remain nameless at this time, and i respect that, pending his findings about the cause of KB... for me, lawyers DO have their uses, but usually they just cause more trouble (and empty your pocket book)... i have a good one, but i dont see any reason to unleash him... thus far, the services my dealer has provided for me, as well as the concern he has shown regarding this situation and his commitment to get to the bottom of things and make right speak volumes...  so far, i am impressed... i wish everyone did business this way... im upholding my end of the agreement and im confident that he will uphold his... this isnt about the money, its about doing the right thing... i just want a rifle that runs like a swiss watch, and is wicked looking (which is what i had)...

I agree. It's impossible for an AR15 to fire out of battery due to the locking bolt design... [red]HOWEVER[/red], it is possible for a round to fire in an out of battery position if the primer is not fully seated. This isn't an uncommon problem with some reloads. The [i]bolt face[/i] slams into the raised primer and... KB!

This may have been an overcharged round, but I would inspect the remaining rounds to look for raised primers, and I would follow up with the range and ammo remfg.

Let me put in a 2 cents worth.  I do not think this could be an overcharge as the case will simply not hold that much.  It should be nearly full of any powder suitable for use in the 223 case.  That said, it is possible that the wrong powder was used.  A case full of Red Dot or Unique could do some strange things in a 223.

I restate, as a reloader, I can tell you with CERTAINTY that some powders that are suitable for .223 are dense enough to allow a dangerous overcharge condition.  Hodgdon H322 is dense enough to allow maybe as much as a 50 percent overcharge, and that does NOT translate to 50 percent overpressure, but much MORE than that.   The charge vs. pressure curve is NOT linear.   This is why we don't push beyond max loads, because pressures start to skyrocket as you exceed the max.



CJ

The range is trying to cover is A$$.

The odds are it WAS the ammo as that is the cause of 99.99% of AR kabooms (usually bad reloads - sometimes bad remanufactured).  

Another possible problem is you didn't have the Cam Pin in place when you put the rifle together.

Fired out of battery?  Can't happen with the AR-15 - the design prevents the firing pin from being physically able to hit the primer unless its in battery.  Only way they fire out of battery is if the primer isn't seated right and the bolt face detonates the primer - cause would then be [b]THE AMMO[/b]

Headspaces wasnt' too short or you wouldn't be closing the bolt with your ammo.  Slighlty over spec headspace also wouldn't cause a problem (Consult [u]Hatcher's Notebook[/u] for the whys and experimental results).

I keep going back to your line:

If you used ultramax I would say it is the ammo.  I am not bashing but just passing on my experience.  I live less than a mile from both black hills ammo and unltramax.  Every place in town has BH ammo on the shelves.  Not all have ultramax.  Their used to be an indoor range in town that would not allow untramax on the range because of "liability issues".  You could however use BH ammo and personal handloads. At the time I thought they were crazy so i bought a box of 9mm Ultramax.  If you took the rounds out and rolled them in your hand you could see rounds that were bulging or poorly crimped.  Haven't used any since.

Most of these commercial reloading companies have liabilty insurance with good reason. Sometimes they have problems resizing fired cases back into specs and running it through the reloading machinery at a fast production pace. Static electricity may cause only a partial amount of powder to drop into one case, then the next case will a full charge, and what was still in the drop tube left over from the last. Most of the reloaders have an over and under powder checker station before the bullet is placed onto the case. On new ammo, the weight of the charged case is a known factor as the cases are from the same lot of manufacure-but on reloads, cases may be from different manufacures, or different lots of same brand, no way to use the QC WEIGHING METHOD. My bet over or under powder charge, as the pictures look Identical to our KB. A high primer could cause an out of battery discharge, I just think that the shell casing would have been at least partialy ejected or part of the rim of the case ripped off. Keep us posted, take a lot of pictures, document everything.  

This was definitely the ammo, I would tell them you want a new gun or you'll take them to small claims court. Don't waste your time and money on a lawyer, just take them to small claims and Get your $1,100 if they don't pay up cash or rifle.

What happend to your AR15 was too much pressure plain and simple. The pressure of the gas that ported into your bolt carrier was so high, it split the carrier and left the bolt stuck in the barrel extension. Resulting in the bent upper, the high pressure escaping from the bottom of the bolt carrier blowing out the magazine and bending the mag well.

This sounds like a big ammo problem, take pics of your hands and the rifle. The range is responsible, I was the manger of a big range down here and we only sold factory for this reason. The ammo company and the range owe you a rifle if they made you use their ammo. If you need any more help let me know.

100% agree with what everyone else is saying here.  I failed to look at your pictures of the gun after the incident.  Even though the results were described as basically being the same (as in my case), they are significantly different.  In viewing the picture in which your bolt carrier is split, that came from one thing only: OVER-PRESSURE.  The round that you were firing was not loaded safely, plain and simple.  It was loaded with the wrong powder or charge, perhaps both.  That explains all of the events/damage that occured to your rifle.

You (and the range) are very lucky that you were not more seriously hurt.  I hope everything works out for you.

Note how the bottom face of the carrier began to rip off.

The the round was in battery, it was charged with a pistol load, and the result was very fast burning and overpressure.

By the time the round traveled past the gas port on the barrel, the overpressure was at near its max (probably several times higher than normal), which was transfered through the gas tube into the carrier, expanding rapidly in the little chamber behind the bolt's gas rings.

The pressure in the chamber at that point was still high enough to keep the round firmly pinned to the chamber walls, so the carrier could only travel back enough to unlock the bolt, although extraction was impossible.

As the pressure built inside the carrier to levels well beyond is allowed maximum, the force caused a split at its weakest point: the two mag-clearing bottom grooves. At this point all the pressure is released in the inside of the gun, blowing the mag apart, inflating the frame, and blowing high pressure superheated gasses towards the bolt as the carrier began to separate (see how the bolt finish looks scorched).

Anyway, that's how it happened.

whew! this has all been highly educational... and highly frightening... i keep getting the idea that i was indeed VERY fortunate to escape with only a silver dollar sized welt and singed hair on my left forearm... im anxious to see what my dealers findings are, provided hes able to get the upper apart... rifle shipped today, but fedex is giving me the run around with ammo shipment... want me to fill out a ton of forms, and TYPE them, no less... funny how you can write out your application for FFL or any other ATF form for that matter, but is that good enough for fedex?  nooooooooo... looks like im calling ups tomorrow...

thanks, all of you... looks like in the future, if i need to shoot soft or hollow points, ill go with a more reputable manufacturer... like maybe black hills...

one of my bosses was a army combat engineer (like i was), and when i showed him the pictures today, his jaw hit the floor... when he was finally able to speak, he said he had never seen anything like this...  

What is the cam pin?  Is it the little T shaped piece that holds the bolt inside the carrier?

Thanks,
--Dan

Glad to hear you are OK other than a few burns and bruses.
Looking at the pictures, I keep getting the idea that a round may have detonated in the mag.
I see what looks like brass residue on the right side of the bolt carrier.
Were there more rounds in the mag?
Were there any funny looking one?
Hot primer? Just my 2 cents.

ADDED Forget what I just asked. I now see the light IE the split bolt carrier.

Sounds to me like a classic case-head separation. There are varying degrees of damage that this can cause.

I have shot tons of Ultramax,it is very accurate in my rifles and I have never had a problem. And yes, they use Lake City brass.

casehead separation wouldnt have done that to his gun.

The bolt would be locked until the gas ported and unlocked the bolt for extraction, so the case head could have been ripped off by the extractor after the round was fired but it wouldn't have done any dammage to the gun.

The problem here was a round loaded way too hot, the gas that ported was way over pressure.