Grendel Kaboom w/ Young's MFG Bolt

[Bill3508]

I'm going to tag this here as I don't have a photo host site. Wondered if you all could comment on this failure. My rifle shot today. If links to other sites are discouraged please delete.
https://www.ar15.com/forums/general/-/5-2087684/?

Thanks.

Bill

[rwh]

I had one of those bolts fail on the first shot. I sent it back and they gave me a replacement. I think I might throw the replacement in the trash. In my case the failure was with a hand load I suspect was overpressure. Even with a hot load the bolt should last more than a few rounds. I would say bolt failure.

[Bill3508]

I had one of those bolts fail on the first shot. I sent it back and they gave me a replacement. I don't think I should throw the replacement in the trash. In my case the failure was with a hand load I suspect was overpressure. Even with a hot load the bolt should last more than a few rounds. I would say bolt failure.

I'm unsure of any other damage right now. Bolt carrier has some scratch's around the cam pin area where when the bolt broke it went slightly lopsided. Other than that a scuff on one of the lugs. And of course brass still lodged in chamber.

[Klem]

Bill,

Looking at the pictures and without any more info I'd say that bolt failed. As the bolt failed it created space, the case was no longer supported and kept expanding until it too failed. One failure occurred before the other in very quick succession. The bolt failure caused the ammo to fail. If the factory round was undersized (i.e. too much headspace) then the case would have separated and the bolt would still be intact. If the round was overcharged I would expect more signs of overpressure on the brass. This, and the history of bolts cracking in this calibre points to bolt failure.

[mdewitt71]

I would be Emailing the maker for sure.... Never seen any bolt break like that and I have seen my share of broken bolts thru guns with over 5K rounds thru em and flat worn out barrels.

Glad I saw this and I can tell you it is not the first time I have seen this brand of bolt fail in the last month.

[204 AR]

How many rounds on this bolt, and when did you buy it? I ask because I have a young, bought last spring sometime I think and it's been good so far. I was thinking of getting another...

[Bill3508]

How many rounds on this bolt, and when did you buy it? I ask because I have a young, bought last spring sometime I think and it's been good so far. I was thinking of getting another...

2 rounds on that bolt. Brand new purchased directly from Young a few months ago.

[Bill3508]

I've added additional pictures to the linked post. Thanks for the replies. I've emailed Young and gave them the link to the post so we'll see what happens. I think the carrier is probably trashed but i hope the barrel isn't.

[muvef]

I'm glad your okay.

I agree with Klem.

[204 AR]

Wow 2 rounds. I going to go out on a limb here and say something went terribly wrong in the manufacture of that bolt somewhere. I will be interested to see how they deal with this. Glad it wasn't worse and you're ok.

[alaska_guy]

Looks like a bad bolt. How did the upper fair?

[Sticks]

Tagged for outcome.

[Bill3508]

Looks like a bad bolt. How did the upper fair?

I think the upper receiver is okay. There was no excess gas back into the receiver. Someone else mentioned that they think the bolt held up long enough for the case to expand to the chamber and most of the gasses went where they were supposed to but let go before the case contracted back.

[LR1955]

B35:

The response that FALRAK (AR-15 .com) and Klem offered is my view as well. The bolt was too brittle and it broke.

And like MD said, I too have never seen that type of bolt failure.

LR55

[rwh]

My CRS is acting up today so I went back and checked my records. I had a young manufacturing bolt identical to the one in this picture that failed on the first shot (see http://www.65grendel.com/forum/showthrea...w-bolt-mfg). The original claim was no more broken lugs. I still have to wonder if their process is to blame for the failures. This is the only bolt I've heard of with multiple failures on the first firing.

[Cowdog]

JP claims that this bolt "boasts a life expectancy of more than 10 times that of a mil-spec bolt." Is it possible they did something unfortunate with the heat treating attempting to get a hard surface and a ductile core? Is the JP high performance bolt safe?

That was the Young Manufacturing bolt that Kaboomed, not the JP bolt.

[Bill3508]

I got the other half of the brass out. Brass fired with the jp bolt measured 1.510". First shot with the Young bolt measured 1.509. Failure brass and 2nd shot with Young bolt measures 1.557". Right now I believe the bolt had begun failing after the first shot as brass is normal with normal primer strike. Second shot primer is nearly pierced and bolt begins collapsing causing the excessive expansion and tearing case in half.

[davidj]

Tagged for outcome.

Me too.

[Bill3508]

Haven't heard from Young yet but it's early. Upper may be a loss as the receiver damage introduced a bulge that binds the carrier. One of the barrel lugs has a rough spot on it but I can see the face to know if it's going to be a problem. Not sure if I could get the high spot in the receiver down enough to save it.

[Bill3508]

Bill,

Looking at the pictures and without any more info I'd say that bolt failed. As the bolt failed it created space, the case was no longer supported and kept expanding until it too failed. One failure occurred before the other in very quick succession. The bolt failure caused the ammo to fail. If the factory round was undersized (i.e. too much headspace) then the case would have separated and the bolt would still be intact. If the round was overcharged I would expect more signs of overpressure on the brass. This, and the history of bolts cracking in this calibre points to bolt failure.

Thanks for your input. Looks to be the scenario.