The grey ring between the center tin plated copper disk and the outer ring raised metal is like a grey epoxy or plastic. Not ceramic or lead. Must be an insulator which leads me to believe they may be electric primed. Why do I feel the center disc is tin plated copper, because I can see a bit of copper under the tin plating and all is non magnetic.
Silver tip is 421 grains.
FMJ GMCS is 391 grains.