I posted this on another forum and never got a definitive answer. What could cause this? The buffer is the original buffer in a COLT large pin Sporter. The only change made was to mill off the sear block (all legal; block wasn’t removed, just milled to be flush with the upper recvr) and a COLT Auto bcg installed.
So there’s more mass than the neutered semi-auto bcg, but still, that shouldn’t harm the buffer, right?
It’s probably fine, at least for the moment. There is or was a burr on the carrier, or if you got it secondhand maybe some grit was in there. Larger diameter rings are sometimes caused by the retention pin, but the buffer shouldn’t touch that during operation if everything is in spec.
If the erosion is through the anodizing, it’ll probably keep going.
How deep is the ring?
Completely normal… or at least fairly common. There could be a sharp angle on the rear of the carrier where the detent notch is machined.
We did a sear block removal too 10 years back for the same reason.
DOOD! Good to see you in here!
Looks a bit unusual, but it’s truly not going to impede anything, function-wise.
Is there a corresponding burr on the back of the carrier?
Can’t remember if I responded over on WaGuns or not.
Carrier was unremarkable, smooth, unblemished… pristine.
Must be some kind of bounce between the carrier and the buffer if it wasn’t there with the old type 2 carrier. It’s not uncommon.
I guess I’d be a little concerned if the gun was a low round count… like under 500 rounds or so.
Round count, despite its age is remarkably low; probably well within that range.
Another commenter on a different forum had suggested that measurement of the two carriers was warranted. I no longer have the old carrier. I was unaware that the two bcg’s, both COLT might differ. Would you suppose that to be merely manufacturing tolerences? Or differences in specifications?
Hmmm… if I get a chance, I’ll pull some of mine open and see what my buffers are looking like. My ACOG gun probably has the highest round count. But I seem to remember that some guns are just worse than others with the buffer scoring.
Since my edit of the comment came previous to your reply, plz allow me to repost that addition as a stand-alone comment/question:
“Another commenter on a different forum had suggested that measurement of the two carriers was warranted. I no longer have the old carrier. I was unaware that the two bcg’s, both COLT might differ. Would you suppose that to be merely manufacturing tolerences? Or differences in specifications?”
it’s approaching 1/16" in depth. Quite significant.
I know for a fact that none of mine look that way, at much higher round counts.
It’s possible the detent hole in the lower is too far back, sp that the carrier smacks it every time it’s fired.
There was no damage prior to replacing the bolt carrier, so I’m disinclined to believe any trouble with the lower.
From suggeztions offered, the most probable seem:
New carrier is, for whatever reason, longer than the original
Bad anodizing.
I have a few possibilities to chase, I was just wondering if someone had already encountered this particular problem and found a solution.
Here’s the first two I grabbed out of the safe:
My weekly ACOG shooter:
Man I’d love to hear what lysander or Scully would have to say on this one.
Do you think it might be something in the middle of the cycle? Maybe the buffer is getting hung up in the tube part way through the return stroke, the carrier continues forward and then the buffer releases and slams into the carrier? Is the rubber bumper still on the buffer or maybe floating around in the tube?
You might be able to lock the bolt back and do a slow mo video on your phone while hitting the bolt release. Might pick something up on that.
Juk, you broke the forum!
I was rubbing my fingertip on the detent cut on the back of my Carrier, and I can feel where the sharp edges would peen the buffer face if there were the slightest sharp edge left on the carrier.
All of my buffers have this to varying degrees.
Yes, that’s definitely noteworthy.
How to tell if it’s a now problem, vs a later problem:
Take the spring off and drop the buffer into the tube. Then the carrier, ass first. You should be able to slide a quarter between then gas key and the top of the lower receiver where the receiver extension (“buffer tube”) threads in. If not, you have a now problem.
If another ring, or tiny dents start forming on the outer edge of the buffer from hitting the retaining pin, you also have a now problem, because that pin will break off and may cause a hard malfunction when it does.
I think it’s reasonable to replace the buffer, or at least have a spare on hand. Someone else may know more about whether it will become a real problem, but with that much wear, through the anodizing, with such a low round count, something is wrong.
Yes, all of my personally owned buffers have rings, but I don’t think they’re deep enough to catch with a fingernail or break through the ano. I checked my work gun out of curiosity, and the ring was just dirty oil that wiped right off. It has very low mileage since its last visit to the armorer’s shop, though. I have no idea what they do to guns there. I know it got a new upper…not sure if that upper came with a new buffer or not. It’s a Block 2, so maybe.
I’ve seen these rings in raggedy ass old guns that have lived a harsh life in a training unit. Can’t remember how deep they get. I’m sure there’s a point where an armorer or depot dude replaces it.
