I've killed a bunch of elk with a 270 & 150gr of various types. I've never shot one with a 308 so I can't speak for that one. The large majority of the time, I'd find the bullet under the hide on the far side no matter where I hit it. I rarely had a through and through. Elk hide is incredibly tough and stretchy and will stop many bullets. That doesn't affect the killing part, though. It just leaves 1 less hole in the hide.
