View Full Version : BCG O-ring?
Sorry if this has been discussed, but I could not find an answer that suited me. I was cleaning my franken-M4gery built with a CMMG MPI BCG. It has performed well for about a thousand rounds, and I was cleaning it today. When I opened the bolt, this O-ring popped out. I cannot figure out where it could have possibly come from, or if it's even needed. Any thoughts?
It is pretty beaten up and flattened out. Could it be the O-ring feom the extractor spring?
https://sphotos-b.xx.fbcdn.net/hphotos-snc7/404229_3918245876747_1102818958_n.jpg
skullworks
10-24-12, 16:25
You say when you opened the bolt. Do you mean when you removed the bolt from the carrier or when you removed the extractor? Either way there shouldn't be an O-ring of that size anywhere inside the weapon (unless maybe in airsoft...)
Tapatapatapatalk
Inkslinger
10-24-12, 16:29
Did you buy the rifle or BCG new or used? Your bolt wouldn't happen to be missing gas rings would it? Too big to be extractor o ring. Can you post a picture of the bolt?
What the hell? I've never seen something like that in an AR.
I am at a total loss too. It fell out as I pulled the bolt from the carrier, there was a lot of resistance, and out popped the ring.
I have shot about 350 rounds since last disassembly, and it has performed flawlessly. After posting this, I ran to a local gun smith who is reputed for building AR's, and he just shook his head.
I have a 3 gun match this weekend, so hopefully it runs!
Thanks for the input.
Danny
Quiet-Matt
10-24-12, 17:22
looks alot like a cross section peice of a bicycle innertube.
What the??? Like everyone else has said there's nothing in the bolt or BCG that looks like that unless some fool put it in to replace a broken gas ring.
So when you pulled the bolt from the carrier this came out behind it?
Any alcohol involved the last time you cleaned it? ;)
Was it having any problems the last time you shot it?
-Jax
Wtf?! I got nothing, I can't think what that possibly could have been.
http://i48.photobucket.com/albums/f240/mvician/BCM3-3.jpg
Inkslinger
10-24-12, 18:04
unless some fool put it in to replace a broken gas ring.
That's what I thought. Bought it used, some schmuck F'd up the gas ring..."Hey, this O ring fits perfect!". Op said he had it disassembled before. I would assume you would have noticed then.
Inkslinger
10-24-12, 18:09
http://i48.photobucket.com/albums/f240/mvician/BCM3-3.jpg
You think that O ring got pounded and stretched that much without breaking? Maybe. I doubt it though. It would have had to be dropped in accidentally. Would it even be possible to make its way out from under the extractor intact?
If the gun was bought used, it could have been the previous owners "experiment" to reduce recoil or maybe some debris from being assembled. It's certainly too large to be the extractor oring.
Just spittin' ideas.
It's FOD. Remove it from the rifle, inspect for other foreign object debris and remove that if found. Re-assemble rifle, lube, test for function and shoot
That's what I thought. Bought it used, some schmuck F'd up the gas ring..."Hey, this O ring fits perfect!". Op said he had it disassembled before. I would assume you would have noticed then.
No offense to the OP but he may have thought it was normal or simply didn't notice if it was sandwiched between two normal rings.
You think that O ring got pounded and stretched that much without breaking? Maybe. I doubt it though. It would have had to be dropped in accidentally. Would it even be possible to make its way out from under the extractor intact?
Well the OP wasn't very clear what he meant by "opened the bolt".
Who knows what someone did when they put it together.
curlyburns5
10-25-12, 17:24
I apologize for not adding anything useful to this thread. But I wanted to say thanks to the OP because it's been a crappy day in the ER and this thread has me laughing my ass off. This reminds me of a patient that came in recently for bowel pains and the x-ray showed a plastic easter egg shoved 6 inches up their rectum.
lethal dose
10-25-12, 18:20
Post pics of everything.
That ring is an inch around. It was behind the bolt tail, inside the carrier?
THe only thing I can guess is that it replaced an oring by someone. I have done that sort of thing in a pinch on a vehicle before but never one a gun. Does it have all 3 gas rings?
Inkslinger
10-25-12, 18:57
I apologize for not adding anything useful to this thread. But I wanted to say thanks to the OP because it's been a crappy day in the ER and this thread has me laughing my ass off. This reminds me of a patient that came in recently for bowel pains and the x-ray showed a plastic easter egg shoved 6 inches up their rectum.
Lol! The weird thing is, the O ring surprises me more! I'm sure their ass was properly staked though.
were the last 1000 rounds shot by you? the last time you cleaned it, did you take the bolt out of the carrier, or was it a more bare bones cleaning? like already asked, was it behind the bolt tail inside the carrier? was it wrapped around close to the gas rings?
It looks almost large enough to have been on a buffer for some unknown reason.
Sent from my SCH-I535 using Tapatalk 2
Post pics of everything.
Maybe it's just me, but I don't wanna see that Easter egg.
Hello everyone, another possible cause for the o-ring.
It's a cheap alternative to Accu-Wedge. On the pivot point. (To reduce receiver "wiggle") You take an o-ring about the size you posted and wrap it around the stand off of the pivot point.
Here is a quick pick. Not sure how it would come loose unless broken or you removed the upper from the lower.
Not my pic.
http://home.comcast.net/~jesse99/o-ring1.jpg
Hope this helps. I've been lurking forever and joined the forums recently!
.
This post has outlived its' usefulness. We all know it doesn't belong where it was found. So let's get over that and focus on more important issues.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.