Not a good idea if you want a humane kill.
and that comes down to shot placment.. if your a good shot and know the distance of the rifle it can be doen humanly.. Now I wouldnt recomend it unless they were close and an easy shot but Ive seen everything big and small shot with a .22lr.. mountain lion 1 shot between the eyes with a round nose (not hollow point) it took 1 step and fell over dead.. that was at around 100-200 feet..all shot placment.. I even saw a guy shoot a deer with one because we were talking and I said it was agianst the regs because it cant kill a deer he open the door and shot 1 on his yard and went see works fine..