204 is great on coyotes, but hell on fox. If you are going to shoot fox I'd suggest a 17 something. That's still no guarantee but your chances are better. Honestly I stopped shooting fox with any centerfire, even a 17FB, as there's usually too much stitching to make it worth while.
Kinda been my experience as well...for fox I like a heavier, slower bullet in a centerfire .22...my favorite is probably a slightly reduced load with a Hornady 50 grain SP in a .222 and Ive had excellent luck with a slightly reduced load in a .223 using a 60 gr NBT... ( Loads going about 2700 fps...)
