His AR15 blew up

[Lazy D]

Oh yeah, seen this happen a few times. Ultimately what happens is the case ruptures right where the extractor sits. When this happens the extractor peels back and locks the bolt into the barrel and extension. The bullet still goes down range and upon passing the gas port 61,000 PSI (5.56 ammo) of gas vents into the carrier. Now is where the kaboom happens. The bolt is locked up and the carrier can not move to the rear and bleed off the gas. Pressure builds and the carrier can't hold it. It always blows out the bottom. If you look at a carrier the thinnest part is at 5 & 7 o'clock were it's made to clear the magazine lips. All the pressure goes right through the mag well. This is the biggest sale point for piston guns. It only happens on gas impingement guns.

 

[FrogFire7]

Oh yeah, seen this happen a few times. Ultimately what happens is the case ruptures right where the extractor sits. When this happens the extractor peels back and locks the bolt into the barrel and extension. The bullet still goes down range and upon passing the gas port 61,000 PSI (5.56 ammo) of gas vents into the carrier. Now is where the kaboom happens. The bolt is locked up and the carrier can not move to the rear and bleed off the gas. Pressure builds and the carrier can't hold it. It always blows out the bottom. If you look at a carrier the thinnest part is at 5 & 7 o'clock were it's made to clear the magazine lips. All the pressure goes right through the mag well. This is the biggest sale point for piston guns. It only happens on gas impingement guns.

Not arguing with you- I have relatively little experience with AR's. It just really surprised me that the gas tube or the carrier key wouldn't be the weak link in that scenario!

 

[Doom2]

Oh yeah, seen this happen a few times. Ultimately what happens is the case ruptures right where the extractor sits. When this happens the extractor peels back and locks the bolt into the barrel and extension. The bullet still goes down range and upon passing the gas port 61,000 PSI (5.56 ammo) of gas vents into the carrier. Now is where the kaboom happens. The bolt is locked up and the carrier can not move to the rear and bleed off the gas. Pressure builds and the carrier can't hold it. It always blows out the bottom. If you look at a carrier the thinnest part is at 5 & 7 o'clock were it's made to clear the magazine lips. All the pressure goes right through the mag well. This is the biggest sale point for piston guns. It only happens on gas impingement guns.

Sorry to say but this scenario make no sense.

 

[Stugots]

My (close) experience involved .223 - 53gr loads. I worked up an accurate load earlier in the spring of that year and everything was fine through the morning shooting P. Dogs (while the temps were a relatively cooler). Things went very south around 2:30PM that day when temps rose up into the mid 80's. After a quite a few rounds on one of my AR15's I had a round go off that ejected the mag, warped and locked up the upper receiver/BCG. After I got home from the trip I took the upper down to the work bench and ended up beating on the BCG with a BFH to dis-lodge the bolt carrier group. Scrapped the BCG and the upper and reduced the powder charge. No problems since then. LIVE and learn...

 

[lyle2231]

That's what they are designed to do in the case of an over pressure situation-- the bcg bananas , the upper swells or splits, and the gas and parts vent down through the magwell.

I'm gonna guess it was operator error related to ammo (especially by looking at him)-- if the bolt is out of battery/not locked in place-- the firing pin isn't long enough to reach the primer-- another safety built into the design.

I'm guessing a squib round/barrel obstruction followed by another round ignition. My 2c.

 

[victor3ranger]

Out of all the lord only knows how many 5.56 rounds I have fired in my career have I seen something like that have had some broken parts and even a titanium firing pin broken but no kaboom

 

[Frog4aday]

Most likely scenario is he mixed in a .300 Blackout round with his .223/5.56 ammo and...kaboom. Happens far too often. Then it's always "no way did I do that". But...let's see the empty case. Well looky there....300 BO.

It doesn't help that people cut down .223 cases to make .300 Blackout cases so the headstamp even says .223 making it just that much easier to make a mistake of putting a .300 AAC BO round into a .223 magazine without noticing. And when they get the bolt open after the destruction, the case may even say .223 on the headstamp (if it is still readable) but it was a .300 BO round in a .223 case. It makes it so easy for people to blame the gun or "factory" ammo when it was "user error". We're all human (even weirdos that dress up and play commando on Youtube.) Mistakes happen. Gotta be REAL CAREFUL if you own both a .223/5.56 gun and a .300 AAC Blackout gun.

LFD Research Films the Firing of .300 Blackout in a .223/5.56 Chamber -

LFD Research simulated a catastrophic failure by chambering a .300 Blackout round into 5.56 AR-15 and filming it in slow motion.

www.thefirearmblog.com

 

[lyle2231]

Most likely scenario is he mixed in a .300 Blackout round with his .223/5.56 ammo and...kaboom. Happens far too often. Then it's always "no way did I do that". But...let's see the empty case. Well looky there....300 BO.

It doesn't help that people cut down .223 cases to make .300 Blackout cases so the headstamp even says .223 making it just that much easier to make a mistake of putting a .300 AAC BO round into a .223 magazine without noticing. And when they get the bolt open after the destruction, the case may even say .223 on the headstamp (if it is still readable) but it was a .300 BO round in a .223 case. It makes it so easy for people to blame the gun or "factory" ammo when it was "user error". We're all human (even weirdos that dress up and play commando on Youtube.) Mistakes happen. Gotta be REAL CAREFUL if you own both a .223/5.56 gun and a .300 AAC Blackout gun.

LFD Research Films the Firing of .300 Blackout in a .223/5.56 Chamber -

LFD Research simulated a catastrophic failure by chambering a .300 Blackout round into 5.56 AR-15 and filming it in slow motion.

www.thefirearmblog.com

I'm trying to picture how a .30 caliber bullet gets pushed that far back into the case by the recoiled inertial weight of a bcg and spring pressure to have ignition in battery?
Im thinking neck tension would prevent the bolt locking up??

 

[436]

I'm trying to picture how a .30 caliber bullet gets pushed that far back into the case by the recoiled inertial weight of a bcg and spring pressure to have ignition in battery?
Im thinking neck tension would prevent the bolt locking up??

Perhaps it was a lack of neck tension; due to a lack of a factory crimp, like the LEE's factory crimp die... I've known a lot of guys that just use neck tension figuring it would be just fine especially when using non-cannelure bullets. So... I'm thinking that a .30 cal might be able to be pushed back far enough, but... the case neck OD on the .300 BK difference always has me scratching my head. The 300 BK OD on the case is something like .3340" and the 5.56x45 NATO is .2531" respectively just saying. I'm sure I have this thing all wrong... just thinking out loud.
Just my 0.2 Cheers.

 

[lyle2231]

Perhaps it was a lack of neck tension; due to a lack of a factory crimp, like the LEE's factory crimp die... I've known a lot of guys that just use neck tension figuring it would be just fine especially when using non-cannelure bullets. So... I'm thinking that a .30 cal might be able to be pushed back far enough, but... the case neck OD on the .300 BK difference always has me scratching my head. The 300 BK OD on the case is something like .3340" and the 5.56x45 NATO is .2531" respectively just saying. I'm sure I have this thing all wrong... just thinking out loud.
Just my 0.2 Cheers.

Thanks for your reply!
A man's intelligence can be measured by how much he agrees with your opinion!
LOL

 

[C-130 Dude]

I'm trying to picture how a .30 caliber bullet gets pushed that far back into the case by the recoiled inertial weight of a bcg and spring pressure to have ignition in battery?
Im thinking neck tension would prevent the bolt locking up??

There are two ways for a bullet to get pushed back, (other than purposely seating it there). The first is seating it too long and the bullet slams into the lands, thus pushing it back. The second is not crimping the bullet, which you should do for semi auto guns to prevent this type of problem. BCG cycling is pretty violent. What you have to be careful of is not crimping it too much. Experiment with a couple of cartridges and set your crimp appropriately. AR gun bullets should have a crimp to prevent unintended bullet movement.

 

[wvbearhunter]

He must be one of those Navy Ranger Green Seal Recon guys.

My bet is either an Out of Battery Discharge or a round did not exit the barrel and the next one hit it

 

[C-130 Dude]

He must be one of those Navy Ranger Green Seal Recon guys.

My bet is either an Out of Battery Discharge or a round did not exit the barrel and the next one hit it

Sounds about right. Better check that firing pin for spec! If it was a squib or blocked barrel, I'm surprised the barrel didn't burst. The other thing it could be is an overcharged cartridge; unlikely, but possible. Or the gun could be just plain dirty.

 

[MachV]

Way to little info to say what exactly happened but the action did what it is designed to do. He admitted to mortering it a few times
# 1 Cans are dirty as you can see by the smoke created. His cleaning regiment could be better?
# 2 his ammo could have been better? Range brass and hot (careless) reloading is not an ARs friend!
# 3 my money is not on a blackout round in this case but that doesnt mean it wasnt.
Some of us are lucky and some make thier own luck. When I was younger I relied way too much on luck but the older I get the more I favor the later!