Hmmmmm, I think that I would choose a 45-70 as I am convienced by those in the know that it will slay the greatest of beeestes!!!

PS
I will use a hammerheaded flip flop dum dum bullet of some 1000 grs at a muzzle velocity of 3000 FPS as tested on my chronograph and proven in battle by none other than Capt. Marvel...