Lightest possible loads for .375H&H?

[Monkeyman]

I'm about to buy a .375H&H rifle for no good reason whatsoever (other than I don't already have one). There is no game I persue that requires a supersonic flying brick to kill and I would rather save my shoulder for more worthy persuits.

I'd like to make up some plinking loads for this gun and was wondering about heavy jacketed .38 revolver bullets over a small charge of quick rifle powder like H4227 or Lil' Gun. Anyone ever done this before? How about a black powder or Pyrodex load? Thanks for any thoughts.