AR rifle buffer questions

[Lastrites]

I reuse them and haven't heard of a pin drifting out to be a real problem, but is something to check if odd short stroke issues are popping up. My sons 5.56 rifle recently had an odd irregular stroke issue out of the blue, I removed the spring & buffer to find the rubber bumper split in half right at the roll pin channel with the end of floating around in the receiver extension. That was a first for me, odd one on a fairly new rifle.