M-16A2 Kaboom

haley · November 19, 2011, 08:46 PM

This happened a few months ago. We had a line of 20 shooters with M-16A2's Using old M193 ammo. 1969 vintage. They were firing at 25 meter targets. All of the shooters were shooting the same lot # ammo and we've shot a lot of it. The shooter who was not an experienced shooter had at least 2 failures to feeds in a row. Then a round chambered and the rifle KABOOMed when he pulled the trigger.
It wasn't the worst I've seen. Bulged the upper receiver tore up the extractor. A lot of energy went down and out thru the bottom of the mag. No injury what so ever to the shooter. Handed him a backup rifle and he kept shooting. Funny thing was there was a very small hole in the target, about half the size of a normal 5.56 bullet hole. We had no more issues during the day and we fired a total of 2000 rounds.
Upon getting back to the shop we got the receivers separated and the bolt disengaged from the barrel lugs. The extractor was tore up and binding up the works. The lower receiver is fine. The bolt and carrier appear fine but will not be reused. The extractor was chewed up but not the worse I’ve ever seen. Upon tapping the bolt back out of the barrel extension the head of the casing completely separated right at the base of the case. This is the thickest part of the case. The extractor ripped a chunk out of the head. The primer was still in the head and extremely flattened out. The remainder of the case is still stuck in the chamber.
The initial opinion on the range was a squib or some other barrel obstruction. There was a Monday morning meeting between the boss and munitions where it was decided that it was a weapons failure. So here the debate begins. The boss says it was a headspace issue and the rifle fired out of battery. I do not understand his logic at all. I’m not sure there is any.
One the rifle was recently gauged and was fine. Two if it had fired out of battery I do not believe the bolt would have been still locked in the barrel extension or that the primer would show clear signs of extreme over pressure.
My theory is that during feeding/chambering do to the same issue as the previous feeding issues the bullet was shoved back deeply into the case but it chambered. Upon firing do to the bullet being tightly forced against the powder charge excessive pressure resulted. It KABOOMed the weapon. Here is where I can use help. I’ve read somewhere that a M193 bullet will disintegrate or break up in flight if it reaches a critical velocity. I know that it is going to be extremely unstable at a high velocity. I’m guessing the reason that there was just one tiny hole in the shooters target was that the bullet left the rifle at a very extreme speed and broke up in flight. But 25 meters is a pretty short distance for that to happen. Any opinions would be appreciated. If someone could point me towards some where I might find some info on 223/5.56 bullets breaking up in flight at high velocity I would appreciate it.
Thanks for your time and efforts.

Mobuck · November 19, 2011, 08:57 PM

Just a guess here. Since fail to feed had occurred previously, I vote for a bullet pushed back into the case creating a high pressure spike.

DnPRK · November 19, 2011, 09:10 PM

It didn't fire out of battery.

The firing pin's collar keeps it from reaching the primer unless the bolt is rotated/collapsed into the locked position.

Play with the BCG and you'll see this is true.

Loader9 · November 19, 2011, 10:03 PM

Quote:

It didn't fire out of battery.
The firing pin's collar keeps it from reaching the primer unless the bolt is rotated/collapsed into the locked position.

^^^^100% accurate and correct. Headspace would not have been an issue. Bullet set back with 1969 crimped and lacquered military ammo is not going to happen either. The shooter most likely had a squibb load that failed to push the bullet out of the barrel completely. I'd say it lodged somewhere just past the gas port. The M193 bullets were known to fragment on impact. Considering you most likely had 2 bullets coming out of the barrel, they most likely were not together anymore but fragments.

hagar · November 19, 2011, 10:39 PM

Don't agree, AR's can fire out of battery. Had about the same thing happen to me during a highpower match. All of a sudden my reloads would not chamber, and me being a dummy distrusted them and loaded some factory ammo, second shot I had a kaboom. Tore up the extractor pretty bad, blew the bottom of the mag out, but no other damage. I suspect that I had a piece of grass or debris in the chamber, my reloads were just a tad too large, but the factory ammo fired out of battery.

cv73 · November 20, 2011, 01:34 AM

i had this happen to me,the bullet pushed back in the case.
now i am always checking to make sure i have a tight crimp.

Willie Lowman · November 20, 2011, 06:19 AM

The round that ka-boomed the rifle was the same round that the shooter failed to chamber two times in a row?

Why wasn't there a spot chamber/barrel obstruction check preformed?

As to what caused the rifle to ka-boom, I blame global warming.

haley · November 20, 2011, 06:32 AM

It was the 3rd round in the mag. The first 2 failure to feeds were ejected. At least one had the bullet pushed back into the case.

madcratebuilder · November 20, 2011, 07:00 AM

Quote:

Originally Posted by hagar

Don't agree, AR's can fire out of battery. Had about the same thing happen to me during a highpower match. All of a sudden my reloads would not chamber, and me being a dummy distrusted them and loaded some factory ammo, second shot I had a kaboom. Tore up the extractor pretty bad, blew the bottom of the mag out, but no other damage. I suspect that I had a piece of grass or debris in the chamber, my reloads were just a tad too large, but the factory ammo fired out of battery.

Remove your BCG from the rifle and look. It is not possible for the firing pin the reach the primer until the bolt has rotated to the locked position.

Willie Lowman · November 20, 2011, 07:06 AM

As far as the little hole in the target goes, it's anybody's guess.

A few years back I saw the bullet core from a 8x57mm where the jacket had completely separated from the core. I don't have any idea why that bullet came apart the way it did (no rifles were harmed).

In the case of your M16A2... If there was an extreme overpressure (and there was) caused by a squib or severe bullet set back the bullet fired may have begun to break up inside the barrel and come apart just past the muzzle.

Just guessing.

November 19, 2011, 08:46 PM	#1
haley Member Join Date: September 13, 2010 Location: Reno Nevada Posts: 52	M-16A2 Kaboom This happened a few months ago. We had a line of 20 shooters with M-16A2's Using old M193 ammo. 1969 vintage. They were firing at 25 meter targets. All of the shooters were shooting the same lot # ammo and we've shot a lot of it. The shooter who was not an experienced shooter had at least 2 failures to feeds in a row. Then a round chambered and the rifle KABOOMed when he pulled the trigger. It wasn't the worst I've seen. Bulged the upper receiver tore up the extractor. A lot of energy went down and out thru the bottom of the mag. No injury what so ever to the shooter. Handed him a backup rifle and he kept shooting. Funny thing was there was a very small hole in the target, about half the size of a normal 5.56 bullet hole. We had no more issues during the day and we fired a total of 2000 rounds. Upon getting back to the shop we got the receivers separated and the bolt disengaged from the barrel lugs. The extractor was tore up and binding up the works. The lower receiver is fine. The bolt and carrier appear fine but will not be reused. The extractor was chewed up but not the worse I’ve ever seen. Upon tapping the bolt back out of the barrel extension the head of the casing completely separated right at the base of the case. This is the thickest part of the case. The extractor ripped a chunk out of the head. The primer was still in the head and extremely flattened out. The remainder of the case is still stuck in the chamber. The initial opinion on the range was a squib or some other barrel obstruction. There was a Monday morning meeting between the boss and munitions where it was decided that it was a weapons failure. So here the debate begins. The boss says it was a headspace issue and the rifle fired out of battery. I do not understand his logic at all. I’m not sure there is any. One the rifle was recently gauged and was fine. Two if it had fired out of battery I do not believe the bolt would have been still locked in the barrel extension or that the primer would show clear signs of extreme over pressure. My theory is that during feeding/chambering do to the same issue as the previous feeding issues the bullet was shoved back deeply into the case but it chambered. Upon firing do to the bullet being tightly forced against the powder charge excessive pressure resulted. It KABOOMed the weapon. Here is where I can use help. I’ve read somewhere that a M193 bullet will disintegrate or break up in flight if it reaches a critical velocity. I know that it is going to be extremely unstable at a high velocity. I’m guessing the reason that there was just one tiny hole in the shooters target was that the bullet left the rifle at a very extreme speed and broke up in flight. But 25 meters is a pretty short distance for that to happen. Any opinions would be appreciated. If someone could point me towards some where I might find some info on 223/5.56 bullets breaking up in flight at high velocity I would appreciate it. Thanks for your time and efforts.

November 19, 2011, 10:39 PM	#5
hagar Senior Member Join Date: February 20, 2000 Location: Colombia, SC Posts: 745	Don't agree, AR's can fire out of battery. Had about the same thing happen to me during a highpower match. All of a sudden my reloads would not chamber, and me being a dummy distrusted them and loaded some factory ammo, second shot I had a kaboom. Tore up the extractor pretty bad, blew the bottom of the mag out, but no other damage. I suspect that I had a piece of grass or debris in the chamber, my reloads were just a tad too large, but the factory ammo fired out of battery. __________________ I don't have time for busy people

November 20, 2011, 06:19 AM	#7
Willie Lowman Senior Member Join Date: March 5, 2009 Location: Uh-Hi-O Posts: 3,006	The round that ka-boomed the rifle was the same round that the shooter failed to chamber two times in a row? Why wasn't there a spot chamber/barrel obstruction check preformed? As to what caused the rifle to ka-boom, I blame global warming. __________________ "9mm has a very long history of being a pointy little bullet moving quickly" --Sevens

November 20, 2011, 07:06 AM	#10
Willie Lowman Senior Member Join Date: March 5, 2009 Location: Uh-Hi-O Posts: 3,006	As far as the little hole in the target goes, it's anybody's guess. A few years back I saw the bullet core from a 8x57mm where the jacket had completely separated from the core. I don't have any idea why that bullet came apart the way it did (no rifles were harmed). In the case of your M16A2... If there was an extreme overpressure (and there was) caused by a squib or severe bullet set back the bullet fired may have begun to break up inside the barrel and come apart just past the muzzle. Just guessing. __________________ "9mm has a very long history of being a pointy little bullet moving quickly" --Sevens

November 19, 2011, 08:57 PM	#2
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	Just a guess here. Since fail to feed had occurred previously, I vote for a bullet pushed back into the case creating a high pressure spike.

November 19, 2011, 09:10 PM	#3
DnPRK Senior Member Join Date: August 24, 2001 Location: LC, Ca Posts: 1,917	It didn't fire out of battery. The firing pin's collar keeps it from reaching the primer unless the bolt is rotated/collapsed into the locked position. Play with the BCG and you'll see this is true.

November 20, 2011, 01:34 AM	#6
cv73 Junior member Join Date: July 4, 2001 Posts: 42	i had this happen to me,the bullet pushed back in the case. now i am always checking to make sure i have a tight crimp.

November 20, 2011, 06:32 AM	#8
haley Member Join Date: September 13, 2010 Location: Reno Nevada Posts: 52	It was the 3rd round in the mag. The first 2 failure to feeds were ejected. At least one had the bullet pushed back into the case.