I shot a couple ringed shells several years ago after I heard of the practice (they were plastic hulls). Forgot all about it until this thread. Shot them from my old H&R single shot break barrel 20 gauge with modified choke. IIRC they shot a bit high and right at 20 yards. Didn't seem to cause any harm to the gun. I would use them in a pinch, but obviously only in a single or double shotgun.
Liberty and freedom often offends those who understand neither.