As I recall bell was credited with killing somewhere around 1,000 elephants. By his own account around 600 of them were killed with the 7x57 (.284 rigby) mostly using military 173 grain full jacketed bullets. He did kill a good number with the 6.5x54
Mannlicher but found they would sometimes bend on hitting heavy bone so went with the slightly thicker 7mmm mostly. They were of approximately the same length & sectional density bullets but the slightly larger dia of the 7mm made them "Stiffer" thus less likely to bend. All of this from Bell's own words which appeared in an article which was published in the American Rifleman back in the 1950's.
Bell knew how to shoot & where to place the bullet, he was not in the habit of "Stopping" charging Elephants, just killing them, a lot of difference.
The most "Versatile" gauge in existence is the 12, hands down.
