"The most absurd aspect of this post is the notion that the correct calibers don't already exist. As Dugaboy1 said above and I posted earlier, there are plenty of cartridges commonly chambered in double rifles that fill the bill nicely from a pure ballistics standpoint.

Or maybe the most absurd thing is the encouragement of shooting game from field positions at much past 250 yards with any gun & cartridge!"

Amen, brother, amen. In addition to my agreement on the first point, shooting any game at long distance should be done from a rest, prone using a support, and only if that is the ONLY way to approach game in the first place (i.e. varmints, mountain critters, etc, all of which must be hunted at 300+ yards.) There are many of us who go out West and tag prairie poodles at way beyond that range, using a portable benchrest and big optics. There is no way to get close enough to shoot offhand if you were silly enough to try. And, would any humane or sane hunter shoot any animal at long range where the risk of wounding it and not following up quickly to finish the job was a possibility.

Remember the old hunting adage, "First, get as close as you can, THEN GET TEN YARDS CLOSER BEFORE YOU SHOOT!"

Dave