SmallCaliberCentral

Has anyone seen this type of failure before?



The bolt is still locked so was not fired out of battery.

Ouch. Can you take a wider angle shot so we can see more?

Never had any kind of failure in my AR, but was reading last week about staking the screws holding the gas key on the carrier so they can't back out. They're also supposed to be torqued to exactly 59 inch pounds. I can imagine how if they come loose it would make a mess of things. It made me kind of nervous thinking about how I take the gas key off when I do a thorough cleaning. Apparently you're never supposed to ever take that apart.

Holy Cow! Never seen that before. Looks like a side charger model. What's the brand? Ammo type?

That is just plain scary.... We need a lot of info on that one...cartridge, bullet, reload?, powder, etc...

Remington cases (shot 4 times), 34 grain Varmint nightmare, 25.1 gr N135 Vihtavuori. Adjustable gas block turned off (single shot mode). Bolt was closed (no slam fire) when shot.

Unless the bolt carrier and bolt just fractured from fatigue, that had to be a considerable pressure spike...The powder is not excessively hot in itself (very comparable to W-748) and unless there was somehow a compressed, or over loaded on just that round.

I can see three distinct fractures on the bolt and it appears that something is sticking out the side of the bolt in the first picture at the "top" of the bolt that appears to be part of a spring or wire, but I can't figure out what it would be, unless part of the small spring in the extractor, pushed through from the pressure..

Is that, by any chance a new bolt carrier group, that wasn't mated to the barrel locking ring??

OldTurtle wrote:Unless the bolt carrier and bolt just fractured from fatigue, that had to be a considerable pressure spike...The powder is not excessively hot in itself (very comparable to W-748) and unless there was somehow a compressed, or over loaded on just that round.

I can see three distinct fractures on the bolt and it appears that something is sticking out the side of the bolt in the first picture at the "top" of the bolt that appears to be part of a spring or wire, but I can't figure out what it would be, unless part of the small spring in the extractor, pushed through from the pressure..

Is that, by any chance a new bolt carrier group, that wasn't mated to the barrel locking ring??

Thanks for the input.
99.9999 percent sure not compressed or over loaded. The small piece was the spring that tried to creep out.
The bolt carrier group was an assembly and had less than 300 rounds through it. I did get the bolt out and it was split from end to end.
I e-mailed pictures to the company that carrier was bought from, they in turn e-mailed pictures to mfg. The company it was bought from put a new one on ups yesterday "no charge"?
We may never know what happened.

I'm glad nobody got hurt.

Are you gonna send those parts back to the manufacturer so their R&D guys can look at them? It might be the beginning of a recall. One never knows.

Looks like the bolt somehow got jammed and pressure from the gas tube ripped the top of the bolt carrier off. OUCH. Very lucky the charge handle didn't blast you in the face. Also be careful using Vihtavuori powders, Their a single base powder and lack the slippery coating. I've found it to frequently get stuck in drop tubes and funnels where other brands don't. I always weigh EVERY charge and check the powder level with a flashlight when finished with 50 round block. When all lined up next to each other it's easy to spot a dangerous condition. Glad to hear nobody got hurt. I would also like to see more pictures .................Was that your first shot with all internal parts being clean??? I see lots of carbon???

Hawkeye Joe wrote:Looks like the bolt somehow got jammed and pressure from the gas tube ripped the top of the bolt carrier off. OUCH. Very lucky the charge handle didn't blast you in the face. Also be careful using Vihtavuori powders, Their a single base powder and lack the slippery coating. I've found it to frequently get stuck in drop tubes and funnels where other brands don't. I always weigh EVERY charge and check the powder level with a flashlight when finished with 50 round block. When all lined up next to each other it's easy to spot a dangerous condition. Glad to hear nobody got hurt. I would also like to see more pictures .................Was that your first shot with all internal parts being clean??? I see lots of carbon???

This ar has an adjustable gas block and it was in the single shot mode. It had been shot 25 to 30 times that day before this happened.
Each load had been weighed by hand one at a time.
The pictures were from the bottom of gun. The gas tube was still on the top of the bolt carrier.
Was able to unlock the bolt and tap the carrier out of the upper.

Head over to http://m4carbine.net/

They have a lot of Industry Professionals on that site. And a lot of the guys over there make their living with the AR platform. Someone will be able to help you.


There is also a thread on how to make your AR more reliable

http://www.m4carbine.net/showthread.php?t=7376

BabaOriley wrote:Ouch. Can you take a wider angle shot so we can see more?

Never had any kind of failure in my AR, but was reading last week about staking the screws holding the gas key on the carrier so they can't back out. They're also supposed to be torqued to exactly 59 inch pounds. I can imagine how if they come loose it would make a mess of things. It made me kind of nervous thinking about how I take the gas key off when I do a thorough cleaning. Apparently you're never supposed to ever take that apart.

Leave your gas key alone. Even in the Army we never took ours apart when cleaning. Just torque it right, and properly stake it, and you'll be GTG

Hi,
Had this happen to a rifle I had been using for years. Somehow, the dis-connector was not functioning properly, and allowed the hammer to fall on a round, that was not fully chambered. Blew the magazine out, in four pieces, rolled the extractor into a bow, bent the bolt, ruined the gas rings, and nearly made me deaf! Other than that, no other damage. I retired it after that, and built a new one. I still have all of the pieces somewhere. strange things can happen to an AR, they can act funny, not shoot right, jam, not chamber, and just plain blow up.

Wayne