The 275H&H Magnum was never that popular even though it
is a superb cartridge. I had a M98 H&H in it, take down
from memory.

Winchester didn't help as they chambered for the
300H&H and 375H&H but not the 275 - probably because
it was very similar to the 270 Win.

Ammo availability wouldn't have been that good either.

It was a cartridge ahead of it's time.