aftermarket or custom made, not a Ruger factory screw or even the escutcheons, let alone the matted spotted finish.............
with the shadows in the picture cannot be certain they are flaired at the bottom, XR3 _Red style...any markings on the back sides?????
A photo of the back side of the grips would be very helpful. You say they appear to be plastic. Could they possibly be bonded Ivory/ simulated ivory? They look as if they have some type of grain to them.