Evidence of hand working on barrel extensions of new colts

**Falar** · 07-28-16, 16:06

I picked up two 6920s recently. One was the one that comes with Magpul MOE furniture and had a serial number around 489,000 the other was an OEM2 closer to 400k.

Both had some shiny spots on the barrel extension where some hand machining/dremeling appears to be done on the most important two lugs. It is easy to see because it is lacking finish in those areas and when looking at it you can tell someone went at it with a die grinder or dremel if you've ever worked with metal. Here is a picture I pulled off the net of a BE and modified with ms paint to show the area I'm talking about:

I don't have optics for these yet and haven't shot them and I'm 100% confident there is no issue as I've never had an issue with a Colt firearm but I'm just curious if this is common now and what the reason behind it is----I've had many an AR over the years and several Colts and never seen this before. I just bought two in two weeks with serial numbers about 70k apart and they both were worked on in this area and it seems unusual to me as I've never seen it before.

Is it a contour "fix" to facilitate feeding?

**Dionysusigma** · 07-28-16, 21:05

That's exactly what the face of the bolt carrier looks like, but silhouetted against the barrel extension. That's not grinding. I've seen it more often than not, in ARs I've owned and built (and I almost exclusively stick with BCM), but have never much cared to figure out why it's like that. Maybe an artifact of test firing?

**Col_Crocs** · 07-29-16, 05:25

He's referring to the feedramps... Specifically, the area he points out with the yellow boxes.

**WS6** · 07-29-16, 06:10

My FN barrel extension is profiled there, and my DD barrels are hand stoned and polished there. My noveske barrel was not, and it was a jamomatic because in part, of that.