AR gurus - how can this happen?

Had a weird breakage/parts self disassembly of a Colt 6721 today.  I don't understand how it happened, and have never even heard of it happening.  

A dude was cleaning his way-too-little fired AR outside of our armory.  This rifle gets fired twice a year for quals, and sits in a case the rest of it's life (detective supervisor who doesn't think he needs it). He says to come look at his rifle. His buffer retainer and spring had come out.  He says he opened it up, and it popped out. I thought he was full of shit and was screwing with something, but the closer I looked, it appeared he didn't screw with anything. 

The RE, RE plate, and nut were all pristine.  Original factory, still staked. The buffer retainer and spring looked fine.  The RE was screwed in what appeared to be the right amount. I could not in any way get the retainer back in without taking the RE crap apart and unscrewing it.  Because it was all where it should be. I replaced the part that came out - the recess looked perfect.  I flexed everything looking for cracks. Nothing. 

What the hell? Has anyone ever heard of this? I wish I would have taken a pic, but my phone was in the car (I can't walk all the way outside and back in - that's too close to exercise).  I cannot - for the life of me, figure out how this thing worked its way out.  It looks impossible. Someone explain this to me and tell me I'm not crazy.  BTW - this was an older, large pin colt with the C carrier. Could this voodoo have something to do with it? 

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It's easy to make assumptions about puppies strapped to missiles, but good science requires research.

 

Joined: 12-2005          Location: Central OK

Original Post

Just thinking out loud here.  If he had the "C" with the milled off bottom and the spring popped out when he separated the upper, from the lower, what exactly was holding the buffer retainer in place up until that point?  

If it were free to pop out as it did, wouldn't it have come out and be loose in the gun most likely?  Why did it come out upon opening it? 

Short of that, the only thing I can think of at all without end-user interference is perfect tolerance stacking and the stars aligning.

I never thought of that. The carrier couldn't have been holding it, and he said it popped out when he broke it open. 

I saved the old retainer - I wonder if I measured it, if it is off in some dimension I just couldn't see with my old eyes. 

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It's easy to make assumptions about puppies strapped to missiles, but good science requires research.

 

Joined: 12-2005          Location: Central OK

Until you mentioned the nut was staked in place, I would've said he was just too embarrassed to tell you he was fucking with the receiver extension and backed it out.  I don't believe Colt changed the dimensions of that part at any point, but my memory could be off.  Maybe the recess for the retaining pin is worn / never cut correctly and slightly oblong?  

KSM posted:

Maybe the recess for the retaining pin is worn / never cut correctly and slightly oblong?  

This would be my first thought,  without photos or having seen the weapon.

I've seen 2 or 3 receiver extensions where the recess for the retaining pin has been just slightly "over recessed" giving the retaining pin enough wiggle room to pop out if you hold your mouth just right.  Granted, I've never seen that on a factory Colt gun, always mix masters put together in someone's garage, but I suppose anything is possible...

--Dave

 

"Do not touch anything unnecessarily. Beware of pretty girls in dance halls and parks who may be spies, as well as bicycles, revolvers, uniforms, arms, dead horses, and men lying on roads -- they are not there accidentally."

Isn't the buffer retainer held in place somewhat by tension from the buffer and action spring even if the receiver extension isn't screwed in EXACTLY right? What I mean is, even if you're a half or full turn off, if you somehow install the part the buffer is going to exert pressure on the buffer retainer and keep it from popping out?

 

That is some weird shit. The only solution is take his rifle away and give him the shotgun he obviously needs. 

 

 

 

 

Joined:      14 January 2010                Location:     Lobster emoticonMAINELobster emoticon

Our policy requires they carry their rifle on duty - only people who request a shotgun get one. Rifles go to everyone. 

Guy told me he never takes his rifle out. Maybe this is the rifle gods punishing him for his lack of insight. 

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It's easy to make assumptions about puppies strapped to missiles, but good science requires research.

 

Joined: 12-2005          Location: Central OK

so our agency bought a batch of CC C8A2's (about 50 units) and we had one do this exact thing. I checked a few of the batch and found that the RE's seemed to be not in deep enough. A quick call and visit from a CC engineer an LE Rep showed that the one rifle was suspect and it appears that the RE needed one more turn to retain the buffer retainer. He explained to me that the design allowed for one more complete turn of the RE to correct the engagement of the buffer retainer. None of the other rifles needed adjustment. 

 

YMMV - it may have been a one off. we have about 180 of them and that was the only one. 

Boltgun

Occams Razor: Whatever is MOST likely is PROBABLY what happened.

If you cannot get the malfunction or action to duplicate, then its PROBABLY operator error.  Which is more likely?

Dude was cleaning his shit and pressed the buffer into the RE and depressed the buffer catch pin, allowing it to pop out.

He has little experience on the weapon and would have just popped it back in, but, he got skeered and ran to the armorer and said "IT JUST POPPED OUT"

Now you have to finish cleaning it.

No touchbacks.

~Will

 




 

 

   Anybody can blow something up, but to disarm anothers bomb, this is when talent, skill, bravery & LUCK will all determine "Success or Failure".  

 

Location: UTAH              Joined: 2003

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