I am trying to locate finger rest baseplates for the 12 round mags for my full size SW99 .40 S & W. I can find them for the Walther .40 P99, but I don't know if they're interchangeable. I need four more magazines & 6 sets of finger rests. I've been all over the internet (including CDNN)but can't seem to locate any. I have them on my SW99 Compact .40 S & W & they work great. Would appreciate any help--Thanks!