I was wondering how much length was needed to make an M4 barrel legal. I took a 14.5" barrel, put a crush washer and birdcage suppressor on it (hand tight), and it came in just under 16" from the face of the bolt to the edge of the supressor. Then I tried two crush washers and it took me just over 16".
Has anyone ever tried pinning two washers and a birdcage? Does anyone make a thick washer for this purpose? This sounds like an intersting idea for someone that wants the M4 look, but doesn't want a Phantom.