RE: 22-250 on Deer
If the military uses 5.56 NATO (a souped up .223 Remington) for warfare I see no reason a similar bullet weight/energy combo would not work for deer.
I know I would not hunt Whitetails with it nor would it be condoned in ANY of my hunting camps. As they say, Your mileage may vary. In any event I have to ask with so many better choices out there why would you want to hunt a deer with one?