Hey, I am in Kuwait finishing up some theater specific training before heading down range for a year in the box. We were doing some CQM and one of the guys had a catastophic failure ofhis M4. It blew the reciever, cracked the upper , sprung the reciver etc. I will be doing a detailed inspection and wll have photos and details inthenext few days. needless to say the rifle is totalled.  Who can tell me what about L2A2 ammo. bullet weight, specs etc. Is this the stuff that was loaded down for the SA80?

The soldier was lucky as hell.
weapon was not neglected, it wasnt rodded after some special training mamo was used and had bore obstruction.
Thats not rust, just some of the very fine sand (like talcum powder)  found in this region.
The 550 cord is for additinal security for the ACOG.
That is a piece of the case wedged down in the carrier along side of the bolt.
The ball ammo was UK manufactured; Radway Green.
Due to possible further investigation by other Army agencies, no attemtp was made to remove the bolt from the reciever. It definitely would not just slide out.
It did not fire out of battery and did not shear the lugs.
The malfunction was not due to a defect in materials, quiete the contrary, it is a testiment to the strength  and quality of the materials tht prevented total fragmentation and serious injury.


I was tasked with investigating and determining what happened.


REPORT - Weapons System Failure
RE: M4 Weapon malfunction and failure

Summary of events:
The incident involved the structural failure of a Colt M4 Carbine while firing ball ammunition from a stationary vehicle on a static range.  

The weapon was fired two days prior using a CQB type of close range marking ammunition  which is a pant marking round with a projectile consisting  of a plastic tip which contains the paint marking substance in conjunction with an aluminum base.

Weapons maintenance was conducted at the end of the training day by their company as a group activity and prior to the live fire range.

The weapon in question was fired and suffered a catastrophic failure of the receiver and bolt
carrier group. The bottom of the magazine was blown out spilling the follower, follower spring
and remaining ammunition inside the cab of  the vehicle. The sides of the upper and lower
receivers suffered extensive damage when they were bulged out when the escaping gases of the
ruptured cartridge bled back through the breech  area.  The weapon was rendered unserviceable
as a result of the extensive structural damage that occurred. The receivers exhibits cracks,
deformation and approximately 1.5 inch section of the bottom front  portion of the bolt carrier is
missing. The bolt locking lugs are visible are  minimally engaged. This in conjunction with the
bolt carrier not being in battery may indicate that the round was not  fully seated causing the bolt
to not fully close but allowed it to close enough so that the  weapon would fire. This would most
likely be due to a blockage in the throat/lead portion of the chamber.  

Equipment/environment/ammunition information:
Date of Incident: 17 Sept 04
Time: approx. 1000 HRS Local Time
Temperature: approx. 120 degrees Fahrenheit
Humidity: >10%
Weather conditions: sunny, no cloud cover,
Location:
Activity: Close Quarters Marksmanship Training
Conditions of range environment: no overhead cover for shooter, weapon or ammunition. Ammunition was exposed to direct sunlight from start of range operations for the morning to time of incident; approximately 4 hours.
Weapon: Colt M4 Carbine, SN XXXXXX
Caliber: 5.56 MM
Sights: Trijicon ACOG 4X NSNI240-01

Ammunition: 5.56mm Ball, L2A2  
Lot Number: 4A1/Y19/S/90/GB/0355
Projectile: FMJ, weight unknown
Markings on side of can include:
11903-02
900 RDS 5.56mm BALL L2A2
10 in CHR
150 IN BDR L4A1
UN 0012          RG 12.07.96

The ammunition used was not M855 ball ammo
but a substitute training round of foreign
manufacture. Bullet weight and composition was
not indicated nor country of origin. It was not
 “green tip” ammunition

FINDINGS:
Colt M4 carbine, SN XXXXXXX suffered a catastrophic failure due to one or multiple bore obstructions attributed to the previous use training ammunition. One or more  projectiles were lodged in the bore of the weapon prior to the firing of standard ball ammunition.
The projectiles lodged in the bore of the barrel created an obstruction or obstructions which
precipitated the subsequent failure of the structural integrity of the weapon receiver and
bolt upon firing. The damage suffered by the weapon is consistent with that normally
associated with bore obstructions in conjunction with the firing of  high-pressure rifle cartridges.

Conclusions:
Without completely disassembling the bolt for the weapon it is impossible to make final determination of the events but speculating based on previous experience the evidence suggests at least two possible scenarios regarding the obstructions and bursting of the weapon.

1. There was one obstruction and the bullet pushed it far enough down the barrel so that both projectiles went past the gas port. The gases bled into the gas tube and back to the carrier key and in turn started rearward movement of the carrier and started to unlock the bolt.  AT this time the now unsupported case head of the cartridge failed releasing high pressure propellant gases into the breech area which in turn caused the bulging and cracking of the receivers and blowing out of the carrier and magazine.

2. There was more than one projectile in the bore and the bullet did not move up the bore any measurable degree. When the rifle was fired the bullet immediately encountered the obstruction, which caused a pressure spike far in excess of what the materials and mechanism were designed to handle. The pressure spike caused an immediate failure of the cartridge case which in turn allowed all of the propellant gases to escape back in to the breech area first coming in contact with the face of the bolt carrier which caused it to move rearward and started the unlocking process
of the bolt. (This is indicated by the position of  the bolt lugs, which are almost completely
unlocked and out of battery) The gases were too great for the carrier to hold at which time the
bottom section of the bolt carrier failed which in turn the carrier stopped its rearward travel and
became wedged in the receiver due to a piece of  the cartridge case being blown back into the
carrier where it broke apart and wedged the carrier open and locked it in place in the receiver.
This piece of carrier coupled with the volume of high pressure gases blew down into and through
the magazine causing the contents of the magazine to be ejected form the magazine body.

The weapon did not fire when initially employed in the drill. It appears that the most likely series of events occurred as follows:
1. The weapon was loaded with a magazine of ball ammo and the normal procedure of pulling back the charging handle and releasing it to chamber a round was utilized.
2. One or more projectiles  remained from the MOUT training and was lodged in the throat/leade are immediately ahead of the chamber. At least one training projectile was lodged in the bore of the weapon at the muzzle.
3. The first round chambered did not seat fully allowing the bolt to rotate to the fully closed and
locked position (in battery) but closed enough that the bolt carrier went forward far enough for the hammer to engage the trigger sear.
4.Subsequently pulling the trigger resulted in the release of the hammer, which pivoted forward but was not able to deliver a solid blow to the firing pin with enough energy to fire the primer due to the bolt not being fully rotated in battery. (The design of the M16 family of weapons allows for the trigger to be pulled and the hammer falling without the bolt being fully in battery but does not allow for the weapon to fire)
5. Immediate action was employed by pulling the charging handle to the rear ejecting the chambered round and chambering a fresh cartridge. (As visibly verified during the event)
6. The charging handle was released, the round was stripped from the magazine with the attendant inertia of the carrier group moving forward to fully chamber the round and push the projectile lodged in the throat farther forward to a point where it allowed the round to seat fully allowing the bolt to go fully into battery.
7. The trigger was pulled again at which time the weapon discharged.
8. The ball projectile started forward movement under firing pressure and immediately encountered the obstruction lodged in the chamber leade
9. The resulting pressure spike exceeded the operating parameters of the weapons system and capabilities/strength of the materials that the weapon is comprised of.
10. The obstruction could not be overcome by the force of the bullets momentum stopping forward movement in the bore. The chamber pressure increased as the powder charge was consumed which in turn further elevated the chamber pressure far beyond the yield tensile strength of the cartridge case.
11. The cartridge case head yielded to the excess pressure spilling the contents into the breech area of the weapon.
12. The gases migrated around the bolt head and down its sides taking the path of least resistance.
13. Powder gases impinged on face of bolt carrier starting rearward movement and the unlocking process.
14. Prior to the bolt rotating out of battery the escaping gases overloaded the carrier and the lower portion of the carrier sheared away wedging the carrier in the upper receiver retarding any further rearward movement.
(Also note that a piece of cartridge case was blown down the bolt carrier and wedged in it).
15. The gases continued down the interior walls of the upper receiver and expanded at
a rate faster than the venting process causing massive expansion of the receiver walls.
16. Gases followed downward after the bottom of the carrier sheared and continued down through magazine body expelling the floor plate spilling the contents of the magazine.
17. Gases traveled down the interior of the upper  receiver and impinged on the recoil spring buffer,
which was still in the forward position. This deflected the gases rationally which caused the failure of the rear upper receiver lug and caused the cracking along the underside of the receiver mounting rail.

Tagged to see the photos

Tagged ...

Hmmm, fired out of battery or had a bore obstruction?

Did he clear a malfunction just before it happened?

Quoted: Hey, I am in Kuwait finishing up some theater specific training before heading down range for a year in the box. We were doing some CQM and one of the guys had a catastophic failure ofhis M4. It blew the reciever, cracked the upper , sprung the reciver etc. I will be doing a detailed inspection and wll have photos and details inthenext few days. needless to say the rifle is totalled.  Who can tell me what about L2A2 ammo. bullet weight, specs etc. Is this the stuff that was loaded down for the SA80? any info will help in making a SWAG as to what happened to cause the failure. I will keep the sight posted.

Isn't L2A2 South African?  I think it's the Radway Green thats downloaded for the L85A2 but I may be mistaken.

tagged

    If you haven't done so already, report this to your ammo people.   I realize it's more paperwork, but there is a process that may bring in civilians (LARs, QASAS, etc) and help you determine if the problem was the weapon or the ammo.    They may also suspend the lot of ammo until the cause can be determined.    You don't want this to happen to anyone else.   One question I guarantee they'll ask:   Was this ammo authorized for use?    

    If you've already done this, never mind.  

Edited to add:  Welcome to the forum.    

Good God...that is one lucky soldier!  Definitely looks like bore obstruction.  Is the guy OK, or did he get shredded by the KFB.

IO1

Was there a jam in this weapon before the shot was fired?  I have seen similar on Edson Range, when a bore had not been rodded after a jam.  A piece of the bullet was still in the start of the barrel, when the next round was seated, it wedged with the fragment and blew the whole side out of the weapon.

It looks like to me that excessive pressure may have played a small roll in the damage to that firearm.

Is that part of the case wedged between the bolt and carrier?

The exterior shape of the weapon don't look to good. I notice corrosion on part of the forward assist.

Perhaps the weapon was neglected?


Hmmmmm .....

Just put some JB Weld on it and sand it out it will be good as new.

Damn...

That "corrosion" looks like some of the talcum-powder like sand you find in the box that blows all around and enjoys mating with excess CLP.

that rifle looks blouted,

I suggest some Peppto.


MadMan

whats with teh para cord tied behind the Delta Ring?

Would it be possible to get a shot of just the bolt and bolt carrier?

What I dont understand is.... if this indeed was a barrel obstruction, and therefore the damage should be contained in *front* of the locked bolt.....  Weapon fires, projectile strikes obstruction, possible KB/swell of barrel under handguards.  How did so much damage occur in the upper receiver?

Unless, the obstruction kept the bolt from going into full battery... but then, how would it have fired?

Or, unless the lugs sheared off the bolt from the pressure, then that would explain the damage..... but for all that damage..... that bolt had to shear or unlock.

Only other thing I could think of is the obstruction was near the muzzle, forward of the gas tube port... causing extreme pressue to be fored back into the upper receiver, both via gas tube and direct from the bore....  this scenario makes the most sense, and might explain the blowing up of the bottom of the carrier, which could not sustain that gas pressure?

I've seen it before a few times, partial bore obstruction is usually the case, Once though it was done by a case seperation (most of the time though a case seperation just blows out through the bottom and ruins the magazine only). Are any of the bolt lugs cracked or missing? Is there a ring in the barrel?

My question is if you replace the bolt carrier and bolt will it fire again?

Why is there sand in the bolt lugs (and elsewhere)?

b

that is from the weapon riding being carried by the soldier for the rest of the day while they were transported back form the range. There is a heck of a lot of dust there.

Quoted: Weapons maintenance was conducted at the end of the training day by their company as a group activity and prior to the live fire range.

If weapons maintenance was conducted, why didn't somebody notice the barrel had an obstruction when cleaning the bore and chamber?

I just talked to a friend that had the exact same result from shooting a round loaded with pistol powder. No bore obstruction. He said the result looked exactly the same.

is there a chance this ammo was sabotaged?

Quoted: I just talked to a friend that had the exact same result from shooting a round loaded with pistol powder. No bore obstruction. He said the result looked exactly the same. is there a chance this ammo was sabotaged?

And the conspiracy theorists have arrived.

Since that gun is toast.

Can I have the lower?

Quoted: Since that gun is toast. Can I have the lower?

ATF might consider it demilled but i doubt it.

Very interesting...
also noted the copious amount of sand on the weapon... hey, I know it happens.
But... I think... its not ammo... although firing the round caused the failure here.
I am leaning toward barrel obstruction...

Y-

Yup, Bore obstruction....lessons to be learned here on the use of unauthorized ammunition, visually checking the bore, PCMS, etc.

Hotgun

Don't worry, my dad's a TV repairman.  He's got lots of tools...

Also for future reference not that this had anyhting to do with the malfunction with this rifle, but the british ammo is loaded to a much lower power quotient than the U.S. Spec ammo is.  This was done in order for the british rifle (L2a2 i think........who cares when you have an AR) to function properly.

HMMMMMMM.......if there is a bullet stuck in the barrel that would explain it

Quoted:
.......Is there a 5.56 interchangeable paint marking round?
quote]

Yes, not widely used...yet.

Hotgun

For the folks asking about sand:

You obviously haven't been in the desert because that sh*t is everywhere. When you work near tactical vehicles in the desert (especially tracked vehicles like bradleys and tanks) they pick up a LOT of sand as they drive around.
If you work in those areas, it'd be advisable to wear some type of scarf to prevent getting a mouthful of sand.

Trust me, when the sand is that fine it can and will get everywhere. If you have any amount of CLP that is staying on the surface of your rifle or rifle parts (like the forward assist roll pin in the picture) sand will find its way there.