A modern howdah pistol is a modern made handgun to a historical design originally for a historical purpose. Hunting dangerous game on top an elephant doesn't really exist any more.

How nice if they stuck to the original design. A .577 or.500 shooting around a 480 gr projectile around 800 to 1100 fps.

A .45/70 might do the same? 550 to 480 grs 800 to 1100 fps?

A .45 Long Colt might as well be in a revolver.

However might still be fun.

Could one of these be rechambered to .45/70?