If you haven’t had the privilege of shooting an AR with a Fostech Echo ll, you’re missing an experience! These triggers work as advertised! They will not out run the bolt/hammer. Completely select-able from single stage normal trigger, to dual Echo firing. On Echo mode, the trigger will shoot when you pull the trigger, and shoot when you release the trigger. If you don’t want to fire the release shot, simply hold the trigger back, and move the safety selector to either “semi mode” or “safe” and it will kill the release shot.