I just got in a box of barnes TSX in 9.3. if I were to hand you one in 375 amd take it back, then hand you one in 9.3 and take it back, you would be hard pressed to tell me which is which. The 375 is not a stopping rifle, the 9,3 is not either. Both will kill any thing that walks, when used poperly. The 375 does have more range because it starts out faster than the 9.3X74r.The 9.3 will do in a pinch. If you shoot a animal at 375 yards with the H&H is it any deader than one shot at 300 with the 9.3x74r. If you are useing either up close and personal it all boils down to shot placement.
Make your shot you live another day, miss it you better hope your PH can shot.

Note also that 450 was not shooting at dangerous game at long range.

JD