No one, and I repeat NO one should be using FMJ for any hunting. PERIOD!! There are too many good choices to even conceder them.
One of my local coyote calling partners uses the 55 gr. ballistic tipped winchester rounds, and sometimes he gets pass throughs with minimal damage on the exit, sometimes he gets a softball sized hole. Every now and then, he has no exit with them. I've used 75 hp's out of my .243 wssm. and had the same results. I've seen a few shot with soft point 100 gr. bullets, and they always exited, but sometimes the exit wasn't much more than a silver dollar. It's a crap shoot.
The .223 with the right ammo. is a pretty good choice. The .22 mag. will and can work, but you'll be limited to shot distance and you better make the shot count when you take it. Expect a few to run off, like the wind, and then die with very little blood to trail. You won't have to worry about exit holes, BUT you might not find all the ones that you hit.