Reading ballistic tables, the .300 Weatherby with 200 grain bullets may be the best elk CARTRIDGE though I think a .340 Weatherby with a 225 is as good or better.
However, I don't care for the weight of the rifles I need them in for me to handle the recoil. Therefore I don't hunt them.
I am just as happy with a 165-180 in my '06 or a 210-225 in my .338. My .308 Norma with a 180-200 may be the best of all, I just don't hunt it much either.
