I have taken quite a few wild hogs over the years. They ranged from a 100 lb sow, to a 450 lb bruiser with three inch tusks. I don't think that hogs are really hard to kill, but they are hard to drop on the spot regardless of what you hit them with. I have dropped two DRT. One with a hotloaded 45/70 and a 405 grain Rem. bullet, the other with my .340 Weatherby, and a 250 TBBC (old style belted base). The .45/70 is a hog gun supreme, but the one I shot with the .340 was a 250 lb boar, and at about 25 yards at last light facing me. I hit him under the chin, and it exited his rear, below a few inches, and slighty to the side of his exhaust port. End to end at that high a speed was impressive to me. The load was clocked at 2950 fps, yet it still held together to go lengthwise.
My favorite hog rifle is my .35 Whelen though. I took my biggest ever with it, and it just plain works.
The next one will be with my .475 Linebaugh more likely than not, but I may use my .404 Jeffery just for fun.