.223 to .264 strikes me as a significant jump. That doesn't mean a .223 won't kill the things you'd typically hunt with a Swede or Creedmoor, but I'd be a lot more comfortable with the .264. I think I'd do pretty much the same with a .264 that I would with .277 or .284. But I would consider the move up to .308 or .323 significant from .264. (Not that I wouldn't have a lot of overlap in what I'd shoot, game wise, but at the distances I would typically shoot, a 180 grain 30-06 or a 196 grain 8x57 is a substantially larger and not really victim to drop/drift enough to matter.) From .308, I think the next jump big enough to really matter is to .366 and a 286 grain bullet.
