The .378 also has one of the quickest "recoil velocities," meaning the acceleration of the rifle upon firing--which can even be more important than recoil energy.
The other factor, of course, is whether the rifle's scope hits your head. This may seem obvious but 30 years ago was in Germany on a writer's tour of the then three Zeiss factories. One stop on the week-long tour was an indoor shooting range, and because Zeiss had been criticized (with some justification) for the recoil-resistance of their scopes back then, one of the rifles including was a .416 Rigby with a lower-magnification variable.
The Zeiss folks invited all of us to shoot the rifle, but many passed, including both me and Jim Carmichel--since we'd already shot .416 Rigbys. But one of the others, an older guy whose name I can't remember, puffed up and said sure, he'd shoot the rifle. He shot offhand (the least obnoxious way to shoot a hard kicker), and the scope's objective bell whacked him in the eyebrow hard enough to make him bleed, even though it had a rubber ring around it. He bled a little, and somehow insisted it hadn't hurt him. (Eye relief was often very short in many Euro-scopes back then.)
Nobody else volunteered to shoot the .416, which isn't surprising.
