One of the great advantages of the .450/.400 is its relatively mild recoil. The "traditional" velocity is 2100-2150 with a 400-grain bullet, and even a 9-pound rifle isn't going to kick all that badly with that. Hornady's load is listed at 2050, which is even milder.
To me the recoil is about like a .375 H&H with 300-grain bullets, certainly not much more. I took an iron-sighted .375 No. 1 to Botswana a few years ago, weight 8-1/4, and used it on a bunch of animals with 300's at 2600 or so, no problem. Personally, I think the No. 1's perceived recoil is a little less with iron sights, since the butt is firmly under your cheek then, and there isn't as much muzzle rise.
Some guys I know have bought No. 1 .450/.400's and loaded them hot, to 2300+ with a 400-grain. This is perfectly safe in a No.1 but makes no sense to me. Why buy a .450/.400 and then make a .416 out of it?
