I love 'em! With my LRB, LMT and Larue lowers... No issues! The only exception is the newest generation 20 (slightly curved) does not drop free on two of my POF lowers. In fact, the latest build mag sticks fast, so I need to take off the upper and pound them out with my fist. The straight 20's are GTG... The Gen 3's... Not so much. YMMV...