07-16-2023, 04:31 PM
Adding a chapter 2 to Klem's, had a friend ( who is an armorer ) who built up a standard 556 and had similar issues. Did the bolt swap, barrel swap, go/no-go gauges, etc with no success. Turned out, the bolt carrier was chrome lined and the thickness of the plating was inconsistent where the bolt neck went thru the smaller aperature in the carrier and was briefly sticking in place. Replaced the carrier with a non-plated one and all was well.