I have a used FN 5.56 barrel, used Colt bolt and some .223 GO NO-GO gauges.
The bolt fully closes on the GO gauge leaving 1/16" - 1/32" of the carrier sticking out the back of the upper. I assume this is tolerable.
The bolt rotates and slightly (1/16" possibly) engages the extension lugs with the NO-GO gauge. Is this something I should be worried about?
I checked the chamber of my other AR tonight (Factory Colt) and the GO gauge seems the same as above. With the NO-GO gauge, the bolt enters the extension and rotates slightly engaging a little less than what happened above. Slapping the side of the upper with my hand made the bolt disengage from the lugs. (This did not happen on the above barrel bolt combo)
I assume that the results of testing my factory Colt with the .223 gauges gives a good example of what I should see. My question is, does the used FN barrel seem to headspace correctly given the information I have provided?