I believe I've seen magazines for a .40 S&W P10, don't know if I have any of the new ones I was buying last year that are marked that way on the package or not.
Sometimes they make stuff most of us don't even know they've made (I've got a new in the package 16 round P09 .40 S&W magazine. Not with the extended base pad, but a flat bottomed 16 round .40 mag. (every other one I've seen holds 15 with the flat base or 17 with the +2 base. No idea how many were made before CZ walked away from the .40's in the plastic framed guns.
Oh, not saying there are .40 S&W CZ P10C pistols out there, but I'm pretty sure they made magazines for them (maybe gearing up to make the pistols before they trashcanned the idea of making them in .40.