My 405gn 458WM Trailboss loads are supposed to be subsonic (1040-1080fps, I haven't crono'ed them though) and certainly are very quiet, which makes them sound a bit weird at the range. If they weren't hard cast I might try them on game larger than rabbits.

I heard stories (maybe urban legend) of a guy in Victoria, many years ago, getting caught and prosecuted for using a silenced 45/70 (ie sub-sonic loads) to hunt deer down that way. He broke a few rules. This suggests that a cast projectile of suitable hardness (or softness) in this calibre and velocity will handle this type of game - does this sound correct?