I just got my barrel from a name brand and it had the smallest gas port hole the chart called for. Would not unlock the bolt. Drilled it out to a #41 which is the next to smallest for a rifle gas system and it started working fine. As for the scratches have you chambered a round and then extracted it without firing? Do this carefully and see if the scratches are still there. If so i would do what it takes or send the barrel back to be fixed. Make sure it is not being scratched by the lugs in the barrel extension. If no scratches then check to see what size the gas port is. There is a chart for port size to position of port here http://www.tacticalmachining.com/lea...ort-sizes.html
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