Bell actually preferred his .256, the British designation for the 6.5x54 Mannlicher-Schoenauer, to the 7x57 for hunting elephants. But the Austrian FMJ ammo tended to split cases during firing--so he switched to his 7x57. But he killed more than "a few" elephants with the .256.
Bell favored DWM ammunition for the quality of its brass, primers, powder and bullet construction, and his 7x57 ammo was, IIRC, DWM.
