Like Bakrch says - just cut it. Carbide is really hard. I've bored bearing inner races, I've cut a ball from a big ball bearing, I've cut the hard portion of HSS drill bits, I've threaded induction hardened shafting - the carbide does not last very long (the chips come off as tiny blue curls). Make your set up as stiff as possible. Should be no problem. If it were me - I have a Top-Notch grooving tool holder, and I'd grind an old insert to whatever thickness was needed for said snap ring.
Let us know how you make out.
