The shape of the375 H&H aids in case extraction and feeding. Very important on a dangerous game rifle
Tapered cases were highly useful for EXTRACTION with temperature sensitive powders . That was the reason for the taper. But for feeding, once the tip of the bullet goes into the chamber the rest will follow and the taper has very little useful effect.
With feeding on a case that hasn't got much taper, it's not the lack of taper per se that sometimes results in rough feeding, but the wide shoulder (together with the wide-angle of the shoulder) that "catches". The wide shoulder results in less taper, but it's the wide shoulder as opposed to the lack of taper that can cause a problem or lack of smoothness in feeding.
