Sorry not been active lately. have a friend's s&w model 66-2 6" .357 mag revolver. he bought it without no rear sight assembly. I have the gun from him with the complete rear sight assembly{not just the rear sight blade.} slide in to slot on top strap ok,but the fronyt of the assembly sticks up from the topstrap. to install the screw that secure it to the topstrap,it would probably strip the threads. wonder if this assembly from s&w is defective. do not want to "butcher" the weapon.