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View Full Version : deep scratches where the carrier rides


Bauer C
05-31-12, 17:42
I got a used colt upper and noticed these scratches where the bcg rides.

None of my other uppers have this kind of wear so i'm a little confused as to how scratches like this could occur.

12392

12393
Iraqgunz
05-31-12, 17:44
Your upper appears to be a victim of overzealous cleaning by the previous owner.
GTifosi
05-31-12, 17:46
Pure speculation, but I'd hazard its toolmarks as a result of dealing with failure(s).
fixit69
05-31-12, 17:52
Looks like scratches due to clearing a malfuction. Do you know the previous owner so you can find out for sure.
Bauer C
05-31-12, 18:06
Can anything be done about it or should it be reliable as is? I know I could just go to the range and find out, but I don't know if I want to subject a new bcg to it just yet.
Casull
05-31-12, 18:19
Scratches can appear for a number of reasons. Here's one instance on camera as a data point: http://www.youtube.com/watch?v=2rLYz2F-QhE

Short of it: The pin in the bolt carrier had a crazy problem.
Bauer C
05-31-12, 21:22
would polishing/refinishing be an option?
dhena81
05-31-12, 21:28
Have you fired it yet?

The scratches don't seem like they could be made by normal shooting. Are the scratches superficial or are they cut into the forging?
Bauer C
05-31-12, 21:36
the scratches are through the finish and into the metal, they are fairly deep
hotbiggun42
05-31-12, 22:50
Just shoot it. yeah the pictures make the scratches look bad but the pictures are close ups of the scratched area and appear to be very shallow. If you are overly concerned take it to a qualified gunsmith for inspection.
Markasaurus
06-01-12, 07:52
To gall that forge aluminum somebody either stuck tools in there to get something out or some kind of bolt failure. That's bad galling considering it should be smooth.
If you can't find out what caused it, you can try polishing it with polish, 0000 steel wool or 800 grit emery clothe in that order then refinish. Or you can leave it, just fire it and see what hapens. I'd check the rest of it for damage closely.
Doc Safari
06-01-12, 09:26
Just shoot it. yeah the pictures make the scratches look bad but the pictures are close ups of the scratched area and appear to be very shallow. If you are overly concerned take it to a qualified gunsmith for inspection.

I agree. It's ugly, but as long as it doesn't affect functioning is there anything to worry about?

For example, in my non-expert opinion I would think just firing the gun wouldn't make the scratches any worse, lead to cracks, or anything else that should concern you.
Brahmzy
06-01-12, 11:25
Cosmetic only. Troubling, but cosmetic. Won't affect funtion. The aluminum may deteriorate/wear faster, now that's it's gouged like that, but upper rec's are dirt cheap anyway.

That said, and not to start a $hitstorm here, since I've moved to NiB carriers, the inside of my uppers pretty much look new. The anodizing has a nice "polished" smooth and slippery feel to it, but is still intact. Kinda cool. The carrier literally feels like it's riding on butter or ballbearings in there with a thin coat of Weapon Shield.

Again, nothing but cosmetic, but proof to the friction model NiB has, or doesn't have. Every upper I used to run with my phosphate carriers would eventually always have deep, smooth wear on them down to the shiny aluminum.
duece71
06-01-12, 13:07
I have some small scratches inside of some of the uppers on my AR's but to me it looks like normal wear down to bear metal. Some of my charging handles have gotten worn down to bear metal as well. Good thing is, when anything like that breaks or is worn very badly, its just replaced.
Blankwaffe
06-01-12, 19:42
To gall that forge aluminum somebody either stuck tools in there to get something out or some kind of bolt failure. That's bad galling considering it should be smooth.
If you can't find out what caused it, you can try polishing it with polish, 0000 steel wool or 800 grit emery clothe in that order then refinish. Or you can leave it, just fire it and see what hapens. I'd check the rest of it for damage closely.

Ive seen similar from the folks who like to use a chamber brush on a drill motor.When the brush is pulled out of the chamber at speed the stainless bristles of the chamber brush gets bumped into the upper as the operator fumbles around.
deadly0311
06-01-12, 19:45
We have a brand spanking new LWRC REPR on the wall that has never been fired, only had the bolt racked a few times and it is digging out the aluminum in the exact same spot. When we asked LWRC about it they said it was normal wear and tear