Solved a weird problem: AR-15 gas ring asplosions

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This is mostly information for anyone else who ends up experiencing the same issues as I did and it would give a good reference on where to start with diagnosing the problem.

I made a franken AR-15 out of parts from a few places. I use an upper, lower, handguard, melonite-coated black gas tube and a bolt carrier group from Spike's Tactical, a 16" barrel from Ellwood Epps with a 1/9" twist rate and a mil-spec trigger group, buffer tube, buffer, buffer spring, etc. All the ergonomics provided by Magpul. I only shoot Federal American Eagle 55gr .223 Rem out of my rifle.

I first took my rifle apart after about 500 rounds to clean it. I didn't have a single stoppage. I looked at the gas rings on the bolt and this is what I saw:

yQnrM.jpg


I inspected the bolt and the carrier... I didn't find anything weird. I replaced the asploded gas ring and shot another 200 rounds through my rifle. The new gas ring also asploded... I decided to use a different cam pin and apparently this solved the problem. After the cam pin was replaced, I checked the gas rings after every 40 rounds to see if one would break again but I was happy to see that the gas rings were all nice and intact. The cam pin was to blame...

Here's a picture of the two different cam pins. The one on the left is the one that came with my Spike's Tactical bolt carrier group that was apparently causing the gas ring issue and the one on the right is another one I bought off the interwebs. The broken gas ring was not enough to cause any kind of stoppage at all and I couldn't feel any difference when I was shooting the rifle with the broken gas ring.

kD1WN.jpg
 
no problem

Buy new gas rings "there like a dollar"

Why would the cam pin have anything to do with the gas rings?????
 
No idea as of yet, but the constant breaking of the gas rings have stopped since I replaced it.

Replacing broken gas rings every few magazines is not normal. It's the first time I've seen this and I inspect C7A2s for a living...
 
I'm used to seeing used gas rings but not broken ones. This is totally new to me and I hope that nothing else is wrong or faulty with my bolt carrier group. :p
 
looks like the angle isnt true, the cam pin hole on the one on the left has angled looking marks around it... looks odd to me...

hard to tell without it in my hand
 
The only thing I can think of is the cam pin is warped, causing the bolt to tilt and put wear on the gas rings

I have seen lots of worn and broken gas rings, but only after thousands of rounds.
 
Oddly, I had a similar issue, after the first 200 rounds on a brand new BCG, one of the gas rings broke… honestly, aside from buying new rings I didn’t put much thought to it...
 
mg4201 said:
Thats a countersink. It looks odd because its on a small cylinder.
Click to expand...

That is correct, the hole through the cam pin has a large countersink. It almost seems excessive in relation to the hole diameter.

I am wondering if this countersink is causing "flexing" or movement of parts that does not normally occur.......

In any case, it it good that you have found a solution that works. I will make a note of your problem abd how it was fixed.

Cheers,

B
 
Bojangles said:
That is correct, the hole through the cam pin has a large countersink. It almost seems excessive in relation to the hole diameter.

I am wondering if this countersink is causing "flexing" or movement of parts that does not normally occur.......

In any case, it it good that you have found a solution that works. I will make a note of your problem abd how it was fixed.

Cheers,

B
Click to expand...

On a piece that short, probably not flexing any significant amount.
 
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