Re: Subsonic reliablity??
I'll bite. My experience is with 200gr SMK into red clay subsonic through transonic and slightly above. Absent hitting a rock the recovered bullets are engrave and sand blasted. The only recovered rock strike had a flattened but not expanded nose. None have opened up. I expect many or most bullets built to handle 3000 fps will act similarly. I'd think some wet phone books could rule out expansion, even if the cannot guarantee it.
If the question were "Can you kill a deer size animal with a pencil hole?" I'd say "SURE!" Lots of white tail fall to the .22RF.
I wouldn't choose subs in my whisper to hunt deer, because I have much better "deer" rifles, but I'm not gonna judge you (generic you) for doing so.
I am interested in your findings. A suicidal coyote has been known to wander into the pasture in front of the bench. Come to think of it, the coyote wouldn't get any consideration regardless of what was laying on the sand bags. . .
Randy