Safari cartridges use fast powder?

[TTSX]

I found a rifle in .375 H&H locally and if anyone remembers, I've been thinking about this cartridge for several years now but up until today, never looked at load data. Well, to my surprise both Barnes and Nosler post data suggesting powders one might use in .308 winchester, such as IMR 4064 or RL15 (which according to Nosler, provided much better results than RL19) rather than what one might use in other belted magnums such as &mm Remington where RL22, H1000 or even retumbo is suggested with a bullet weighing 2/3 what the .375 does, traveling at similar velocities. I was always lead to believe that big bullets in big cases needed slow powder but it seems the professionals are telling me different. Does anyone have insight/experience as to why this is?

Read More

 

[Member 18201]

Difference in bore diameter relative to case capacity.

The larger bore "vents" the powder more rapidly.