I will agree with anyone that says that you shouldn't use anything smaller than a .243 Winchester and go one step further to say that a .243 shouldn't be used as a kids gun because you have to be selective in where you shoot to make a ethical shot on a large whitetail deer.
That gets my vote!
I also have to say i love the .222 Rem. cartridge... I have a 12ga. .222 combogun that i've harvested a ton of meat with, but to me a wolf is the biggest thing i'd shoot with a .222... (or .223 for that matter)
I've also had other .222's including bench rest rifles that were amazing accurate!
DM