I think it depends where you are hunting. If you are in the brush/woods most of the time and your shots are under 150 yards there is nothing wrong with the 30.30. In fact i would argue it being so compact, lightweight etc.. makes it a great choice. I still see plenty of them around here in the midwest. If you will be mixing it up with some field hunting, long range etc.. i think the .243 is better. The one BIG problem i have with the .243 in the woods in that if you hit the slightest of twigs that bullet is gone. Now that will happen with any bullet, but the .30 bullet will hold better and you MAY not miss what you are shooting at. I agree above the .243 is about minimum for deer IMO.. That doesn't mean i am right, but just the sheer size of the bullet (yes, i know about the energy it carries) sticks out at me as being on the edge of being too small.