I'm going out on a limb here, but I will suggest that John Kingsley-Heath recommended the.243 because most of his clients could better put a .243 bullet in the right place than could be done with a hard-kicking magnum.
Likely, but also a lesson on what is enough for the task. Don't forget that the tradition built around a 7x57 is based on being enough for the task and its shootability. Same with a .243 or .270 as recommended by Aagaard, whether its trendy on here to like one or not.
"Enough for the task" is never an interesting topic compared to the ever mythical "best for the task" after all, what else would we talk about around the campfire?
I gotta confine my remarks to what I've done or seen, and my "large game" at it's largest was a black bear that weighed about 350. I killed it with a 30-06 200NP. My brother, same trip killed an almost identical bear with a .243 100 Hornady. My brothers bear died almost where he shot it. Mine traveled maybe 75 yards
Both our shots were placed very similarly, with mine maybe an inch or so back from where I'd intended. I was shaky from a bad dismount and getting my 16EE stuck in a stirrup. Hard to shoot when you're laughing...
But... the fact remains, at least firmly in my mind, that the .243 with a good bullet (or fast .25) is a faster light switch than just about any standard .30 rifle, for game under about maybe 500 lbs. Granted that there may be .308 bullets made to offset that, but I doubt that any of those are 180s or heavier.
Do I think that a .30 (or .32, .33. .35) is suitable? Yeah, no problem. I'd do it with what I had, and a .308 Winchester is one of the easy buttons in life. Go with any good load. I loaded 50 of those .30/200 noslers for that bear hunt and used 1 on that hunt. Shot the rest at coyotes, a couple of deer and one antelope over the next couple of seasons. They worked perfectly.
And I get that some want a rifle just for African game and the "African" experience. I get it that the .243 Winchester doesn't work to that end. And there is some merit in carrying more rifle and bullet when in some locales. I didn't load the .30/200s in my 30-06 because I felt they were necessary for a black bear. We were hunting in an area known to harbor a grizzly population, and I didn't want to be unprepared.
I actually felt a bit cheated that no grizzlies were seen on the trip.
Don't know or communicate with any African PHs. If one of them recommends a rifle/cartridge combo I'd guess it's because, in his experience, it works.
