So I meet my buddy last night for a few beers after work. He's been a gunsmith at the same shop since he came home from Viet Nam. Anyway, he starts telling me about a new RRA that a customer brought in for repairs because it wouldn't Ex/Ej. Long story short, after going through the entire gas system, he found that the gas key was not drilled completely out. It was drilled out enough for the gas tube to fit, but that was it. It wasn't plugged anywhere, just not drilled out. He replaced the gas key and everything worked fine after that. I have seen/heard of the carrier not being drilled with gas ports, but not the gas key. Just a 'head's-up' in case anyone else experiences this problem on any AR, not just RRA.