From my readings before WW2 the 9.3x62 was much more popular than the .375 H&H .Possibly because of the relatively (at the time)inexpensive Mauser bolt action rifles available but also because ammunition was less expensive and the 9.3x62 worked so well .It has been compared with the .375 for years ,most notably by Finn Aagaard who with his partner Joe Cheffings attained their PH licenses together many times shooting the same species at the same time . Finn observed that he saw no difference in the killing power of his Winchester 70 in .375 and Cheffings' 9.3x62 FN Mauser .He had many side by side comparisons to judge from.