9.3X62...I had a combination gun (Ferlach) in 12 ga./9.3X72R. Either one of these 9.3's are bad medicine. The European 9.3 is roughly equilavent to the British 375. If memory serves me correctly my 9.3X74R was close in ballistic performance to a 375 Holland & Holland Magnum with the 375 having about 10-20% more in most categories.
Factory loads are a bit difficult to compare because there are not a great deal of "common" bullet grains to compare. I did find one comparable load: A 270 grain bullet "hand-loaded" for the 9.3X72R runs 2300 FPS and has 3172 Foot Lbs. of energy. The 375 H&H Mag. runs a "factory" load (usually a tad less power than a handload) at 2600 FPS and 4050 Foot Lbs. of energy! That comparison shows a 30% difference. Just sayin'. Guido's round is probably more comparable to the 375 Winchester. Terrific load at medium distance...and doesn't stomp ya' nearly as bad as the H&H.
Best, Capt. Chris