Update: Visited MMC last week and they agreed with what most of you had said about the gas key. They were polite and accepted it without question and I didn't even show a receipt. The customer service guy said that it was either loose or debris had gotten between the gas key and the bolt carrier during assembly. He swapped out the whole BCG and did a test fire. It functioned without error with the 7 test shots he ran through it. I will shoot it this weekend for myself. I'll hold off judgement to sell or not until I've shot it again.
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