.460 Wby. I have never fired the .378, so I can compare the two, but the .460 gets your attention.
Another one that I didn't like was a Whitworth Express that weighed about 7 pounds in .458 Win.
Neither of the above were fun to shoot.
Of all the guns I have fired that hurt worse than they should have, considering their muzzle energy and type of loads was a 16 gauge Savage Autoloader. It was made on the design of a hump backed Browning, and I think it was something called a long recoiling action.
It was much worse than any shotgun I have ever fired, and I have fired a lot of 3 inch 12 gauge in my OU.
Speaking of slugs, and the comments on the forum about how they hurt. My first deer gun was a 16 guage 6 pound Ithica pump. I used slugs, and as well as I remember, it wasn't all that bad.
