Nat's right. I've got Capsticks books, although it's been a while since I read them, but, if I remember correctly he was refering to following up wounded leopards. Shotguns are quick and powerful for close up fast shooting, and in his opinion, and mine also, no gun is quicker on the second shot than a double gun. You'd never have time for a third most likely since the charge would come at a range measured in feet not yards. He also wore a football helmet, heavy leather coat, and a leather neck protector.
Again, IIRC, he prefered what he called SG buckshot, which he said was the British designation for what we call Number 1.