We're talking about a thin skinned cat here, almost surely up a tree and shooting from a blind. Considering the cats weight I would have thought any accurate deer rifle that's legal calibre would easily do the trick. The 257 WM would be lethal. Of course a good result all comes down to placing the shot properly in the first place. Not having shot a leopold but having shot plenty of other animals including the big old tough red stags and heavily constructed tahr over long ranges I would be quite happy with my current 7mm-08, super accurate 140gr Sierras and plant the damn bullet through the shoulders, in the neck, or up in the brisket if frontal. None of this pissing around with fancy bullets and magic loads and then fluffing with a gut shot or one low in the chest or abdomen as seen in some postings on the forums. Although I would have my 404 in Africa I would not even consider using it when blind shooting.