I just added a Aimtech Warhammer full length rail to my Mossy 500, as well as an M4 clone from Primary arms. Love the rail, installed easily, has held tight after heavy use (and some blue loctite) looks awesome and gives me the mounting flexibilty I always wanted. The rail is raised for use of the stock bead sight as well. Transitioning between red dot and the bead sight is pretty smooth. This is my home defense/zombie killer!