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Page AR-15 » Troubleshooting
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Posted: 7/19/2010 7:55:53 AM EDT
I've recently begun to notice that my 16" carbine is making quite the "CLACK" sound when I pull the charging handle all the way back, almost sounds like something is smacking the rear of the buffer tube.  I have a standard carbine buffer and spring in there but I never noticed this till recently.  Do I need to replace the buffer and spring?
Link Posted: 7/19/2010 10:00:08 AM EDT
I'd start by looking at the bumper on the back of the buffer.
Link Posted: 7/19/2010 10:22:54 AM EDT
I was at the range last fall with a buddy who was shooting his Bushmaster.
He noticed that the bolt was not locking back, and looked at it for him.

I found that the nylon end cap on the buffer was only crimped in place, not pinned like Colt.  The cap was working it's way out of the buffer and preventing the buffer from moving all the way back.
Had it moved much farther, the cap would have been hitting the end of the buffer tube.
Link Posted: 7/19/2010 10:34:25 AM EDT
Link Posted: 7/19/2010 4:30:49 PM EDT
Carbine buffer has nothing to do with the barrel length, but the length of the receiver extension.

Hence if you have a telescoping stock, then you need a carbine buffer.  If you have a standard fixed stock, then you need a full length buffer.

Now if you have a carbine buffer and carbine spring in a fixed stock, then chances are what you are hearing is the back of the carrier key making contact with the back of the lower receiver (buffer not limiting out the B/C correctly and chancing a cracked receiver).

On the other hand if you do have the right buffer in play, pull it and check for debris down the tube. Could be a blown primer that has found it's way down the tube and the noise you are hearing.

I've tried this carbine buffer and spring in two seperate carbine buffer tubes, both are clear of any debris.  I'm pretty sure the sound I am hearing is in fact the carrier key hitting the receiver.  I wonder why this would be happening with the proper buffer, spring, and receiver extension.
Link Posted: 7/20/2010 7:13:06 AM EDT
Link Posted: 7/20/2010 6:24:27 PM EDT
Pull all the way back on the charging handle and confirm that the face of the bolt does not retract behind the back of the ejection port.

If it does, then something is wrong, and/or you are using a carbine buffer in a full length receiver extension.

Again, barrel length has nothing to do with the buffer, it's the length of the receiver extension tube (inner void) that dictates the needed length of the buffer.

The boltface does not retract beyond the ejection port.  I am using a carbine buffer and spring in a 2 position colt carbine receiver extenstion

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