We're talking follow ups on wounded Leopard only here right?

Every PH will have his own opinion but FWIW, I always use my ordinary carry rifle which is a .500 Jeffery. Another PH who works for us likes to use a 12 gauge side by side. We did a night follow up together last year (in Masailand) and stopped the charge at 6 yards with simultaneous shots from both firearms....and there was obviously only time for one shot each.

The charge of 12 gauge hit the cat full in the face, broke the jaw on both sides and did some damage to the cat's dental work - whether it would have killed him, I don't know - but my guess is that it probably would. My shot from the .500 hit the cat in the face and exited out of his ass - and was definately a fatal shot. Combined the cat dropped like it had been struck by lightning.

Colin still uses his 12 gauge in similar situations and I still have faith in my .500.

Someone mentioned scopes...... IMO, they'll be a far greater hindrance in this situation than anything else. Here's a link to the trophy photo, the cat in question is at the bottom right of the page and below is a photo taken from where we shot from...... I'm kneeling where the cat fell.... Needless to say, the sling wasn't on the rifle the previous night!

http://www.kuduland.com/hunting-in-tanzania.htm