Oddly enough, Bryan Litz did an interview at SHOT with UR, about a paper he will be releasing/maybe has released already, about the research he is doing on .22 ammo and it's ballistics tendencies vs sound barrier and subsonic crossover.
It's interesting , explains a lot of stuff as why 22 ammo can be so fickle. This vid only got put up yesterday, paper may be out already;
https://www.youtube.com/watch?v=uMjjWdPcnXA