I saw a deer shot with a subsonic round from a Ruger 77/44. 335 grain cast bullet at about 1000 FPS did pretty well.
The buck that was shot dropped to the ground and kicked for about 10 seconds. There where 4 other deer near by watched it kick and when it stopped they went back to eating.
Shot placement is everything! I would rather take a round of 50BMG to the foot than a 22short to the base of the skull.
all 26 of my guns are 45/70 govt, 357 mag, 22 or 12 ga... I believe in keeping it simple. Wish my wife did as well...