In my view, 22 mag is over kill for squirrels. I use hollow point subsonic at 1050 fps. That seems to be just right. The other regular hollow point over 1200 fps is just too loud for me and a little over kill as well. I have killed foxes with the subsonic hollow point with only one shot to the vital area. I've tried CCI CB and Regmington CBEEs. The CB and CBEEs are only effective if you hit the squirrel in the head. Even in the chest cavity it's not powerful enough to kill the squirrel right away. It might get to a hole before dying.

So far, the best one for small games like squirrel and rabbits are the 1050 fps hollow point subsonic amo. The 40 gr CCI and winchester hollow points are my favorites.

My 2 cent.