H1000, or Retumbo for 375 H&H ?

[COASTED]

Anyone out there ever try either of these powders for the 375?
I got some brand new powder handed to me and I'd like some idea of what a beginning load might be, and of course whether it would be worth the trouble in the first place.
thanks

 

[Andy]

They're both too slow for that round, even with the heaviest bullets - you'll be working well below their optimum pressure range, and will get inconsistent powder ignition. Something like H4350 is much better suited to the 375 H&H.

 

[MTM]

Way too slow.