My .375s are my go-to rifles for just about every hunting application. Outside of Africa the following load has proven to be sub-moa and as deadly as needed.
.375 Holland and Holland Magnum
235 GRAIN SPEER – 83 GRAINS - IMR 4350 – CCI Standard Primer
By "standard" primer, do you mean CCI 200???? That is a standard rifle primer. I'd think you'd want to use a magnum primer (CCI 250) to ignite that much powder.
