You can actually be overgunned, people say thats not true but it is. The .338 is designed for big game, its bullet is designed for bone crushing penetration,the heavy bullet can punch through a little 'ol whitetail without breaking a sweat and getting no expansion, so the size of the hole can be .338 in diameter, a .243's expanded diameter reaches .5 of an inch, a .30 calibercan be .65. A 45-70 would probably not expand well on a whitetail either but thats a big hole, .45 of an inch.
Target resistance plays into expansion. Deer just dont really offer any resistance so to speak of.Generally one would want total penetration with exit, with total expansion. The more tissue damage the faster the kills, so tecnically hollow points and bullet fragmentation only ads to the killing power, but not if it does it before reaching both lungs.