MCMXI,
I'll match your "good friend who's been a professional guide for 30 years, who is paid to speak all over the country and who won't use anything smaller than a .300 Win Mag for elk" with an elk outfitter from Colorado. At the time I got to know him 10-12 years ago, he's been guiding and outfitting elk hunters for 30 years, and Colorado has more elk than any other state.
He and his guides liked to exchange info on what rifles and bullets their clients used, and the results, and since those clients took around 30 elk a year, I thought this might be statistically valid info. So I asked him what cartridge he thought was a good minimum for elk, and he said, "Two-fifty-seven."
I asked, "Roberts or Weatherby?"
He said, "Either one!"
