I have a Perazzi COMP1 pull Top Single Trigger. It obviously fires the top barrel as it only has one hammer in the trigger although a O/U trigger. I have the second hammer and parts to put it back to an O/U trigger. Although fitted to a COMP1, it will fit MX8 drop out trigger receivers as they are similar. Phillips Gunsmithing just tuned up this trigger and replaced parts as necessary and reblued the trigger guard. Asking $550.