Phil, my .416Rigby runs standard loads. I think it is more attest to how hot the load is in my .375H&H.
Yep, I figured that would be the situation. Federal lists there 400gr ammo velocities from 2300-2400fps. A 300gr .375 runs about 2500-2600, so yeah recoil would be similar.
My .416 Rigby loads were running north of 2600fps, that packs a whallop on one's shoulder.