If anyone has Bob Hagel's "Game Loads and Practical Ballistics for the American Hunter" or "Guns, Loads and Hunting Tips" one of them contains a good discussion of what to use for mountain lion hunting. I have both books so forget which one that info is in.
IIRC he thought fairly highly of a .22 Magnum for treed cats but I could be misremembering that.
He wrote an article on hunting mountain lion for "Handloader" and recommended a Keith bullet out of the 45 Auto-Rim, among other similar Keith style loads.
