Paul, in the outline shape of the side plate (lock) whatever screws are there have to come out. Two screws on the left and one on the right side plate (FW frame). The screw in the front on a FW frame is a little over 1/4" long and fastens directly into the receiver. Why the engineers deemed it necessary to put another screw in the side plate is anybodies guess. They both still have a slight lip on the narrow part of the plate to slip into the receiver to align them. As I stated before make sure the gun is cocked or else the hammer will prevent you from putting the plate on.