the 243 is more rifle than the 30-30 ballisticaly basically it has more powder behind it and is movin alot faster than a 30-30 since the 30-30 has such a heavy bullet you would have to lob it in on a deer because of the drop where as a 270 is light and is a 30-06 case necked down to a 270 caliber bullet so you have a light fast bullet which could shoot a deer at 400 yards + if needed

the 30-30 is a flat nosed bullet so it creates more wind resistance than the 30-06 cartridge which usually cased with a more areodynamic bullet with more bullet weights and options so that is why it is a better caliber