There is no accounting for poor bullet performance which limits penetration. This is not a condemnation of the calibre, but only of the bullets used.
; As to the 12 bore being an Elephant gun, this 'history' belongs to India, where it was the 'second' choice, the 14 bore being the primary and more popular size for ll dangerous Indian game. It's history of being a great elephant calibre stems back to the mid 1800's with the use of hardened ROUND balls and black powder - "through and through" was Baker's quote and that was with a mere 4 to 4 1/2 drams of Curtis and Harvey's best. The contention was that the 12 or 10 wasn't needed as the 14 would shoot all the way through their head. Certainly through and through should work. After that, they played somewhat with explosive 8 and 10 bore slugs for tigers with penetration normally limited to 10 or 12" - adjustable, of course by varrying from soft to hard bullets.
; How that pertains to African Elephants, I don't know - but HARD balls or bullets must be used.