A .25 to .30 deer rifle would be perfect medicine for a leopard from a blind. My concern for any follow up would be whether the scope has a very low end power (1 or 1.25). I can't comment on the handguns and the bullet performance - I am sure that if the range is short enough for an accurate shot that a .500 would be more than powerful enough, but would agree with others that leopard don't require an overly hard bullet.