This is my Ruger P94 9mm . I just saw this on the underside of the frame. just forward of the trigger. Does it look like a machine or casting mark or a crack ? To me it looks like a molding mark from casting but I always like a second opinion. I rubbed my finger along it and it is raised very slightly and I put it under my magnifying glass. To me it looks like a casting mark. Thanks for any information.