slight barrel extension lug peening on BCM complete upper - Page 1

AR-15 » Troubleshooting

AR Sponsor:

Site Notices

[ARCHIVED THREAD] - slight barrel extension lug peening on BCM complete upper

Posted: 3/29/2016 10:31:32 PM EDT

BCM complete upper. Has about 1500 rounds down it. Had it for a while now and never noticed until recently. The lugs on the extension appear to be getting dinged a bit. It is not all of them. Circled in red. The peening is on the circled one a few others. Also the extractor seems to be scratching up the breech face a little. It doesnt look like it has peended the metal but has scratched it a bit. It is also circled in red. It is a bit hard to see but it is there. Here are some pictures.

Bolt doesn't have any peening.

thoughts? Should I be concerned about any of this?

Posted: 3/30/2016 12:24:29 PM EDT

[#1]

Bump for any ideas if this is something to be concerned about.

Posted: 3/30/2016 1:10:22 PM EDT

[#2]

I think the grooves you are seeing are from a non-relevant manufacturing goof. The greenish finish would be worn off if it was being scraped or peening, and it can't really be peening because the bolt doesn't smack into the extension. It goes past it, then starts turning to lock "stars."

I also do not believe the bolt touches the chamber opening, but if the extractor were doing so, it looks like it only did it long enough to wear into each other. That is normal for parts to mate up. I have never seen the arc you are describing, but I wouldn't worry about it in the least bit.

Posted: 3/30/2016 5:19:21 PM EDT

[#3]

I realize the bolt isn't designed to hit the lugs but I was concerned that the lugs and bolt weren't lining up properly thereby making a small amount of contact causing the peening.

Posted: 3/30/2016 8:09:06 PM EDT

[#4]

I have no idea what causes it but I had 2 PSA uppers that did it and PSA refunded my money. You should ask for a mod to move this thread to AR Discussions and you will get more responses.

Posted: 3/30/2016 10:05:27 PM EDT

[#5]

The grooves in the barrel extension are machining marks. That's definitely not from your bolt. This wouldn't concern me.

The mark on the chamber face is puzzling. It does look like the extractor made the mark. Appears to be a self-correcting problem

I'd send pics to BCM and see what they say.

Posted: 3/30/2016 10:42:19 PM EDT

[#6]

I'd send it to bcm but I modified the receiver group. I took the fsb off and shaved it down and reinstalled. I can ask them but I don't expect them to do anything done i modified it.

Posted: 3/30/2016 10:45:38 PM EDT

[#7]

Quote History

Quoted:
The grooves in the barrel extension are machining marks. That's definitely not from your bolt. This wouldn't concern me.

The mark on the chamber face is puzzling. It does look like the extractor made the mark. Appears to be a self-correcting problem

I'd send pics to BCM and see what they say.

View Quote

I disassembled the bolt and installed it so I could see if the marks line up with the extractor and they do.

Posted: 3/31/2016 7:01:02 AM EDT

[#8]

Quote History

Quoted:

I disassembled the bolt and installed it so I could see if the marks line up with the extractor and they do.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
The grooves in the barrel extension are machining marks. That's definitely not from your bolt. This wouldn't concern me.

The mark on the chamber face is puzzling. It does look like the extractor made the mark. Appears to be a self-correcting problem

I'd send pics to BCM and see what they say.

I disassembled the bolt and installed it so I could see if the marks line up with the extractor and they do.

I didn't have any doubt that it would. It's pretty obvious your extractor is "touching" the chamber face.

Posted: 3/31/2016 7:03:00 AM EDT

[#9]

Quote History

Quoted:
I'd send it to bcm but I modified the receiver group. I took the fsb off and shaved it down and reinstalled. I can ask them but I don't expect them to do anything done i modified it.

View Quote

Send them the pictures you took with a brief explanation. If you've still got the info from the purchase, you might include that was well so they know it was a factory-built upper.

BCM customer service is all over the map. They might offer to fix or they might tell you to get lost. It won't cost you anything to find out.

Posted: 4/1/2016 9:21:51 AM EDT

[#10]

There is nothing wrong, or worth worrying about on your rifle. If the bolt was causing the grooves, it would show corresponding damage on the bolt lugs. The extractor probably touched for the first few rounds, and is no longer worth mentioning. If it was doing anything more than just kissing the face of the chamber opening, you would have chambering problems.

Posted: 4/5/2016 10:38:53 PM EDT

[#11]

Quote History

Quoted:
There is nothing wrong, or worth worrying about on your rifle. If the bolt was causing the grooves, it would show corresponding damage on the bolt lugs. The extractor probably touched for the first few rounds, and is no longer worth mentioning. If it was doing anything more than just kissing the face of the chamber opening, you would have chambering problems.

View Quote

Could it be marks from when the head space was adjusted when the barrel manufacturer put the barrel extension on?

Posted: 4/28/2016 2:33:39 PM EDT

[#12]

Just wanted to update. I talked to bcm and they took the upper in and looked it over. I just got it back today. It doesn't look like they did anything and there was no note or anything. I can see they test fired it but that's it. Should I assume since there was no note or explanation of anything that it is fine?