I was thinking to get myself a big bore African game rifle and looked at the 416 Rigby. From my experience in shotgunning, if the gun doesn't fit you, it will bitch slap you pretty good. If you are really interested in taking on this caliber, get a gun that fits (and use proper form). Also, it won't hurt to put a good recoil pad on it, like a Kick Eez or Pachmyer (sp ??). And maybe as a last resort, to use a shoulder recoil pad like the PAST or use a shotgun vest with a pad like the Browning Reactar pad. If you use all three things above, I think the 416 should be manageable. Yeah, you probably won't use a recoil vest or harness like a PAST out in the "field" while hunting big game but it does allow you to at least give you some range time familiarizing yourself with this caliber and getting use to it without it bruising you around.
I'm at work so I can't get youtube up, but I did find a youtube vid of a young skinny kid in Australia shooting a 375HH with just a tank top on and it didnt phase him one bit. If the 416 is a bit more, a grown adult should be able to handle it.
Worse recoil I had experienced was 3" magnum slugs through a stock Benelli M2 tactical with no PAST recoil harness or shooting vest pad. I emptied about 10 rounds and was hurting bad.