Randy, on paper a .223, .22-250, etc, will deliver enough fpe to qualify as a deer killer.And as you already know it's legal to do so in TN. The problem you'll have is in bullet selection. Thin skinned, high velocity .22 centerfires might not have the structural integrity to stay together while punching the hole in deer sized animals. In the hands of an expert rifleman, sure it will kill but don't say I didn't warn you if the deer you shoot can't be recovered when you blister it with a .223. Live targets deserve your respect and bullets that can be expected to kill 100% of the time.As a 40 year deer hunter I wouldn't recommend anything less than 6mm or .243 for even the smallest whitetail. Use enough gun and save the .223 for varmints and such.