Is the buffer normal?

[Clyde777]

Is this normal wear for a buffer with only 50 rounds through it? The buffer was new and put into my bcm lower and upper middy. Is the wear normal/okay?
51852

[grizzman]

I'm feeling a bit of deja vu on this one.

Buffer wear is normal, though I'm not sure if there should be that much wear in only 50 rounds. Who made the buffer?

[Clyde777]

I managed to get a better picture.
51854

Its the buffer that came in my bcm complete lower from bcm so I think its a bcm h buffer. I noticed the same in my other bcm lower rifle as well. As long as it wont mess with the function I don't really care.

[grizzman]

Your link isn't working, but the first photo was adequate.

[kirkland]

Not normal. How deep are those marks. Check the back of your carrier, any burrs sticking out or is it smooth?

Could also be coming from the buffer retaining pin. When you close the upper and lower together, does the carrier push the buffer back off of the retaining pin slightly? It should.

You said you saw the same thing on your other lower. Did you shoot that same upper on your other lower?

[Clyde777]

They are not very deep but you can feel them. The carrier is smooth.

[grizzman]

I agree that it's very likely caused by the buffer retaining pin. While the upper is closed onto the lower, the carrier should slightly rub against the buffer, moving it rearward a small fraction of an inch.

Calling it normal isn't quite the correct term....I'd like to change it to "not uncommon". My 6.8 with an LMT carrier, built with Mega receivers, exhibits it more than my other ARs, but others (but I may have run their buffers in the 6.8 for short periods), and yet others not at all. My BCM lower, which is typically paired with a BCM upper, is the 2nd most affected.

If there's much of a gap between the buffer and carrier, the pin will likely eventually be bent towards the carrier. This would likely reduce the impact forces on the pin to a degree and lessen the gouging. An excessive case of this can eventually cause the pin to break. In most cases, I'd guess it's caused by simple tolerance stacking.... retainer pin hole at one end of the tolerance and a carrier length/position at the other.

Calling BCM for their feedback wouldn't hurt.

[GH41]

Its the buffer that came in my bcm complete lower from bcm so I think its a bcm h buffer. I noticed the same in my other bcm lower rifle as well. As long as it wont mess with the function I don't really care.

Confused... Is the buffer getting beat up when installed in the BCM lower. It almost sounds like you took it out of a BCM lower and put it something else. "Its the buffer that came in my bcm complete lower" Read this>> https://truenortharms.com/products/ar-15-offset-buffer-retainer

[Clyde777]

Its a BCM buffer that came in the BCM lower.

[twm134]

Have you tried emailing BCM? This seems excessive for only 50 rounds.

[Clyde777]

I emailed them yesterday. I will report back what they say.

[Madmotorhead]

This has been answered in the other forum.
You removed the retainer pin and the marks persist .
The back of the retainer pin slot on the carrier has burrs on it obviously.
Therefore sand the back of the carrier flat on some 400 grit on a flat surface and deburr these burrs with a small file or stone.

51876

[ace4059]

It’s not a problem with the buffer, it’s caused by a burr on the BCG. Deburr and don’t worry about it.

[Stickman]

Is this normal wear for a buffer with only 50 rounds through it? The buffer was new and put into my bcm lower and upper middy. Is the wear normal/okay?
51852


It is fine, it won't hurt anything.

[bb223]

Is your receiver extension not screwed in far enough?

Only time I've seen that type of wear was on lower where the receiver extension could've used another rotation, went ahead and did such a rotation and the marks stopped.