Nice pistol
May have been re-blued once already, or else the paint has come off the "S" and "F" (should be white and red)
I believe that the grips were similar to Bakelite, but the red/brown were actually a wood/plastic composite. Those grips look correct for a '42 AC
This forum is full of good advice etc, but if I may make a suggestion, the following site may yield even more expert advice
http://p38forum.com/
I enjoy my '44 P.38 very much. Truly historic pistol on several levels