Ram-Line 30-rd polymer "Combo Mags" (fit mini-14, AR-15, and AR-180) have been 100% reliable in my experience, except for one that had the spring in backwards (I turned the spring around and it has since worked fine). I also have one Triple K Brand steel magazine (30-rd) that has never failed to feed. Stay away from the nickel-plated 20-rounders sometimes seen at gun shows--I have tried two and neither one worked. I also had an Eagle brand 35-rounder that also fed flawlessly, but it developed stress cracks around the mag spring anchor rivets (Eagle mags use a coiled spring that anchors near the top of the mag and unwinds as the follower is pushed down).