9mm blow up

[abunaitoo]

Had another 9mm blow up yesterday.
No one got hurt.
9mm AR
Not sure what caused this one.
Most of the time, the primer goes off before chambering.
This one has a firing pin hit to the primer.
Suppose to be factory ammo.
We've had a few of these happen from time to time.
Friend almost died when a tiny piece hit him in the side.
Went to the hospital and it had nicked his spleen.
Has no spleen now. Seems you cannot stitch a spleen.
He's doing fine now.
Attachment 242136Attachment 242137Attachment 242138

[Winger Ed.]

Something is wrong with that weapon,
it looks like it is getting a slam fire when the firing pin isn't retracted, and the bolt isn't closed.

This function is not to be confused with something that is made to fire from and open bolt and has a fixed firing pin.
They have heavy bolts and real strong springs to push it into battery, and are designed to work like that.

Not that something wild would do that in a properly functioning weapon, but what do ya mean, "supposed to be factory" ammo?

[abunaitoo]

I know about slam fire.
Used to happen all the time on my MAS semi auto.
Heavy floating firing pin. Machined some weight off to make it lighter.
Problem solved.
Haven't seen a fixed firing pin rifle, in a semi auto, for a long, long time.
I kind of remember working on one once. Forget what it was, or what caliber.
Never worked on a 9mm AR, so I don't know if it has the same floating firing pin as the .223 AR.
Could be the cause.
Pistol primers have softer cup.
Owner said it was factory. Had a box of factory on the table. It looked like factory ammo. Box was more than half empty.
I didn't ask anymore about the ammo.
Didn't want to make it seem like I didn't believe him.
I always try NOT to make them feel like it's something they did wrong.
Don't want to come off like I know everything.
BUT.........I never assume anything. No matter what is said.
And keep it to myself. Less chance of offending someone I don't know.
Keeps me safe, and out of trouble.
As I said, we've had a few of these happen over the years.
Most are caused by the bolt hitting the primer when feeding.
This one has a clear primer hit. Plus the primer is backed out a little.
Owner didn't know if it chambered, and he pulled the trigger, or not.
All he remembered is it went bang, and jammed.

[Winger Ed.]

Just curious about the ammo. For that event, it wouldn't matter what they were.

Those primers were struck by the firing pin, and those rounds went off before they were fully chambered.
Cases won't look like that if it happened fully chambered without the barrel blowing apart.
Even then, there wouldn't be the bulges, they'd be fully ruptured, or more nearly shattered & shredded.

I'd take it all apart, strip down the bolt too, clean it well, and take a look.
It might just be too dirty for the firing pin to retract like it should

[trapper9260]

The shotgun my dad gave me that is a pump. It would after you shot the first round. Then when you pump it to put another one in the chamber .the 2nd one would at times go off. I was a use to it. But was thinking that if I let someone use it with me and not use to it something bad would go wrong.I had some one fix it. It was a bent spring. Now it is fine no problems. Just to give you a idea about how it happened not only to semi auto .

[Sig556r]

Pics#1 & #3 seem to indicate it wasn't fully chambered when the primer went off, which may mean that it fired while bolt is loading the round.
Good thing no one got hurt.

[skeet1]

Pics#1 & #3 seem to indicate it wasn't fully chambered when the primer went off, which may mean that it fired while bolt is loading the round.
Good thing no one got hurt.

I agree this rifle fired out of battery while the round was being chambered. possibly a stuck firing pin.


Ken

[phonejack]

I would check to see if the firing pin is jammed in the forward position. Either from a factory defect or lack of channel cleaning. It should freely slide in and out by shaking the bolt carrier.

[SSGOldfart]

Was this gun a factory built or homebuilt?

[popper]

OOB firing. Check FP, dirty channel or bent. Possible (not likely with factory ammo) large case. Factory box means nothing. I do NOT put reloads in factory box.

[DCP]

You might want to check the range out!
Be on the lookout for the Menehune.
Lots of strange things going on there.

[edp2k]

A 9 mm AR is a blow back operated gun.
In a 223 AR, which has a separate bolt and bolt carrier, the bolt must rotate sufficiently (in lockup/battery)
to allow the FP to protrude from the bolt face and reach the primer.
The 9 mm AR has a one piece bolt+carrier, and the only thing that keep it from firing out of battery
is how much the rear of the FP extends past the back of the bolt, and how far rearward the bolt can be and still allow the hammer
to touch the rear of the FP.

If the bolt is too far back, the hammer will hit the lower edge of the bolt before it can reach the FP.
With today's put-together-from-parts 9mm ARs, tolerance stack and just plain loose tolerances
can produce a parts tolerance stack up such that the bolt can be significantly (i.e. dangerously) out of battery (i.e. rearward) and
still allow the hammer to reach the FP.

combine the fact that a 9 mm AR is a blow back gun, and thus the chamber gets very cruddy, and people may not use sufficient lube and
then shoot 100's of rounds without cleaning or lubing, you have a recipe for the bolt to not return 100% to battery (forward) when the trigger is pulled.
if you have the aforementioned bad tolerance stack up, you get an out-of-battery firing event. boom.

if the FP is indeed not stuck forward, this is what happened.
One solution is to take 0.010" off the rear of the FP and then put an empty primed case in the chamber, put a small piece of 1/8 inch cardboard
in between the bolt and the breach face, pull the trigger, and see if you can get the primer to go off.
if it does, take off another 0.010" and try again.

[tomme boy]

Just about ALL 9mm AR9's will fire out of battery. Most all new ones are coming with a spring on the firing pin so it will not slam fire.

Find out which extractor it has. Seems to happen more with bolts that have the 1911 style extractor. The newer ones with the ar15 extractor it is not happening no where as often as the 1911. The round gets stuck in front of the extractor and the gun is fired and you get what is exactly shown.

[243winxb]

"A 9 mm AR is a blow back operated gun." As posted above, is the problem.

[Hick]

Brass looks surprisingly grungy to be factory

[flyingmonkey35]

sorry for your friend.

but as a guy who has had two guns blow up on me. I do not take this lightly.

unless you can completely I'd this issue as your fault.

send the gun back to the factory. if it's a custom built rifle send the complete bcg back to the factory.

DO NOT ignore this.

if this was your firearm your friend has a good cause to sue you for medical damages.

factory's can't fix problems if they don't know about them.

Sent from my SM-G960U using Tapatalk

[country gent]

On semi autos the drag of the cartridge coming out of the mag slows cushions the bolts closing. I suspect a heavy buffer spring and light mag drag contributed to this. even a sticky firing pin should reach the firing pin until its in battery. If part of this conversion is a firing pin spring Look at it for collapsed coils or breaks. Look at the firing pins nose for thinness, sharp edges and length. Check pin to be sure its free, straight and not binding.

[jj850]

Just about ALL 9mm AR9's will fire out of battery. Most all new ones are coming with a spring on the firing pin so it will not slam fire.

Find out which extractor it has. Seems to happen more with bolts that have the 1911 style extractor. The newer ones with the ar15 extractor it is not happening no where as often as the 1911. The round gets stuck in front of the extractor and the gun is fired and you get what is exactly shown.

help me if I am thinking about this wrong, but if the round is in front of the extractor how will the firing pin reach it

[abunaitoo]

Didn't know the guy.
Didn't get any information on the rifle.
He did shoot more after, and all was good.
When I went back, he was gone.
I did find some 9mm cases by where he was.
Cases very dirty. Lots of carbon all over.
When my friend got hit, he was over 3 feet away.
Tiny little hole that wouldn't stop bleeding.
He said he felt fine, but another friend took him to the hospital.
Good Thing. Might have saved his life.

[root]

Look like they came out of my lage max 10/31.

Get those every now and then due to it being open bolt slow fire.

That gun in the OP has a issue though.
I agee check the FP and channel.

Rich