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Discussion Starter · #1 ·
Belonging to a friend is a soup sandwich.
It’s ATI Omnimaxx in 5.56.
This thing routinely stove-pipes and double feeds rounds.
He asked me (like I would know!?) why it does that. He also showed me the buffer face... it is beating against the buffer retaining pin BAD.

I said it needs to go back to the factory. Ideas?
 

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I am just getting into the world of AR's. Have read that almost all feeding problems are gassed related. Either over or running under gassed. The way most are set up, they tend to run overgassed. Sounds to me like this is what is happening here. There are many good trouble shooting videos to be found on youtube or maybe you can get some insight at AR15.com. Possibly the least expensive attempt at a fix is a heavier buffer spring, heavier buffer or adjustable gas block......................... but one could replace these and still not fix the problem. I saw one video where the guy suggested having at least one heavier spring and a heavier buffer on hand anyway. (I have not done this with mine yet)
 

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The Shadow (Moderator)
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I agree that it's most likely a gas issue. I would guess it's over-gassed, being a pistol but....

Assuming the Bolt carrier isn't a gnarly clawed thing, that seems to be that it isn't a great fit in the upper; and can "rock" around when it beats against the buffer.
 

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I said it needs to go back to the factory. Ideas?
I think you're right.

I don't have an encyclopedic level of experience, but of the AR's I've worked with, (a growing number), I've yet to see a buffer beat up like that. All of my rifles have seen a fair amount of use, and not a one has a single dent in the buffer. I've not seen that in any of the several AR's I've assisted others with.

You could grab a couple heavier buffers, a buffer spring with more, or an adjustable gas block, but on a factory gun, I'd hesitate to install any other parts until the manufacturer walked away from the problem.
 

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On a factory gun, send it back. If home built than add a heavier buffer and spring (like a H2 or H3).




CD
 

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Hmmm,.. gas block, feed ramps, buffer spring, mag spring, chamber, ammo, etc. etc.,... take your pick.

I would start with the most likely. This type of malfunction correction is basically an
elimination process. Most frustrating is when the malfunction is a product of two combined possibilities,...
that's when things start getting interesting, or, should I more rightly say,... extremely frustrating!

The best of luck to your friend!
 

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Discussion Starter · #8 ·
I need to check back with him to see what he's doing.
I really think I would send it back for repair/refund.
 

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Send

If is a new gun, and it is, send it back. It is the simplest and best option.
Pete
 

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Discussion Starter · #10 ·
I need to check back with him to see what he's doing.
I really think I would send it back for repair/refund.
Two years later he never addressed the issue.
I wonder if the bolt body itself is too short.
Doesn't the buffer normally rest on/at the aft end of the bolt? If the bolt was too short the buffer would impact the retaining pin when cycling forward...
 

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The Shadow (Moderator)
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1) I wonder if the bolt body itself is too short.
2) Doesn't the buffer normally rest on/at the aft end of the bolt?
3) If the bolt was too short the buffer would impact the retaining pin when cycling forward...
Need to clean up some terminology of parts names.

1) The bolt body never touches the buffer. So I think you mean the Carrier.
2) No, but it may technically touch the rear of the Carrier. It doesn't supply any tangible amount of force though, or you wouldn't be able to push the takedown pin out and open the gun. Also why that buffer retainer is where it is.

3) If the Carrier was short, it would get an "extra" run at the buffer. I mean that in the sense of pushing less mass, and therefore being able to, in theory, "throw" the carrier ahead of it. But the peening wouldn't look like that simply because of the carrier, unless the rear of the carrier was toothed somehow.
After revisiting the above picture, it almost looks like the buffer spring is either sagged, bound, something... It appears to be held back off of the buffer retainer, but as if it was bashing and getting peened by it.
So to the rest of your point, yes; the retainer does contact the buffer normally. It's the sacrificial lamb, as it were. But if things are assembled and working properly, wearing one out isn't a common event.

Cheers
 

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Discussion Starter · #12 ·
Need to clean up some terminology of parts names.

1) The bolt body never touches the buffer. So I think you mean the Carrier.
2) No, but it may technically touch the rear of the Carrier. It doesn't supply any tangible amount of force though, or you wouldn't be able to push the takedown pin out and open the gun. Also why that buffer retainer is where it is.

3) If the Carrier was short, it would get an "extra" run at the buffer. I mean that in the sense of pushing less mass, and therefore being able to, in theory, "throw" the carrier ahead of it. But the peening wouldn't look like that simply because of the carrier, unless the rear of the carrier was toothed somehow.
After revisiting the above picture, it almost looks like the buffer spring is either sagged, bound, something... It appears to be held back off of the buffer retainer, but as if it was bashing and getting peened by it.
So to the rest of your point, yes; the retainer does contact the buffer normally. It's the sacrificial lamb, as it were. But if things are assembled and working properly, wearing one out isn't a common event.

Cheers
1. Yes, bolt carrier is what I meant (old brain).

3. Yes, it looks like the buffer is bashing/getting peened by the retainer pin. I would never put up with that from a manufacturer/assembler. He did.

I guess eventually either the pin will break or the buffer edge will wear away... Then when he opens the upper the buffer will come out like a "snake in a can":geek:
 
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