I you have the circular wear on your buffer it's typically from the rough finish or a sharp edge of the carrier, almost always there's a sharp edge at the bottom groove. If you're buffer is getting chewed up on it's outer edge really bad (looks like someones beat it up with a chisel and hammer) it could be that the buffer detent hole in the lower receiver is machined too far rearward which doesn't allow the carrier to push the buffer off of the detent when the upper is assembled on the lower.
I had a early Essential Arms lower receiver that had this problem (my first AR in 1987).
Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
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