So, what do you think happened?

It's rarely one thing that causes a failure like that, but a combination of things.
Hard to tell from the pic, but is the extractor snapped too?
 
Hitzy said:
It's rarely one thing that causes a failure like that, but a combination of things.
Hard to tell from the pic, but is the extractor snapped too?
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MTOzU9V.jpg
 
Rocket Surgery said:
That's not good advice, it's 2017 right now, and if you have no social media presence it looks really bad when you're looking for work. What employers look for mostly is to see if they're hiring a liability, IE some crazy social justice warrior or right wing blowhard.

If you're competing for jobs from last century, like the trades etc, it doesn't matter you can post whatever you want.
Click to expand...

This is an example of why I stay away from social media, typical narrow analysis of the real world. What are " Jobs from the last century"?
 
yomomma said:
MTOzU9V.jpg
Click to expand...

So the right lug disintegrated, the left lug held up, but the bolt cracked through the face on that side...yet the case didn't rupture.
I'm thinking the bolt was not fully engaged when it was fired by the way the left lug cracked... force was applied to the top part of the lug for it to twist/crack like that. The longer right lug will snap off easier. I don't think anything really was wrong with the bolt, something prevented the bolt from closing fully before firing. The firing pin bridge/notch in the receivers are suppose to prevent firing out of battery, but are rarely in spec on Norks.
 
so far , Hitzy and the Medic make the most sense to me. norc bolts do have some too hard, and some too soft. that one looks brittle. bolt face has taken a beating, never seen the bevels near the ejector before. no rupture of the brass, so it was seated, lugs probably not fully rotated into lock at ignition, which could be a short chamber( carbon build up in shoulders). that's as good as I can guess.
 
So, OP and any others who would care to add an opinion:
IF a piece of schmutz in the op-rod grease prevented the bolt roller from completing it's rotation and the lugs weren't able to fully lock, do you think your USGI or SAI or LRB bolt would have survived any better than this Norinco bolt?
 
No damage to extractor, no damage to the case... so I don't think this is about a hard extraction. Nor do I think the lugs failed, as one is intact, as my guess is if it failed under pressure the case would be damaged.

Instead I look at the operating rod: its damaged. Its not on the receiver properly. And where the oprod contacts the bolt roller is the bolt failure point.

I propose that there was too much pressure, for some reason, and that pushed the oprod way faster/harder than normal operation, and broke the bolt before it could fully impart all the inertia to the bolt to fully cycle.

Now why might there be extra high pressure? Ammo might have had the wrong powder type, maybe an accidental use of shotgun or pistol powder. Or maybe the gas ports were clogged. Or maybe the powder was flawed somehow, not burning at its proper speed. I don't know, possibly something else.

Ooh... a carbon fouled gas block, combined with 200grain or 240 grain reloads??!?! I seem to remember something about M-14 and M1 designs being limited to lighter projectiles due to oprods bending and failing. But that was known long ago.

I'm no expert, but I think its worth considering oprod velocity and gas port overpressure.
 
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