This December will be my very first Mountain Lion hunt. It's on horseback and with hounds.

I'm assuming that the lion is taken out of a tree.

For those of you that have hunted these kittys, which gun should I use?

A lever-action 30-30 is pretty good for that.

Vapordog, I hunt these cats every year. My recomondation is... any gun you feel comfortable with, they are not hard to kill at all and dont pose much of a threat.
a few things to consider.... the heart is literaly "behind the shoulder" moreso than say a deer, and if you hunt them on the ground and get a raking shot... beware that they are very very thin animals and make sure of your angle

Never shot a lion and never hunted one, so don't claim to be an expert.

I do know lots of guys who have hunted them here in Idaho in the winter and they say you may get lucky and get a quick tree and you may not.

Also on horseback may not mean all the time, cougars tend to head for rough country when the dogs are after them.

If you are hunting rough country with the potential for having to hike on foot through a lot of snow or bust your way through brushy canyons, if it were me I would be carrying a pistol.
As the others have posted it doesn't take a cannon to kill a cougar.

Personally, I'd use my old Model 94 Winchester .30-30, or else my Model 92 Winchester .44-40.

AD

I have a pair of '92 Winchesters.......a .25-20 and a .44 mag. Would anyone use either of them?

Either on will work buddy! I would go with the one you shoot best and is longer range shooting. The 25-20 you took to africa would work fine I am sure! We take about 6 to 10 cats a year and most are shot with .44 mag handguns or an open sighted 30-30! Good Luck!

Heck of a deal...it appears I'll put that old .25-20 in a scabbard and holster the Ruger super blackhawk in .44 mag on my hip, get on that horse and chase some cat around Utah in December.

Damn this is becoming an exciting year!!!!!

I think a Browning lever rifle in 243 win would be a sweet cougar rifle. Nice thing with it is it will give you alot more range if that situation were to present itself. The BLR in a 270 may really be the "cat's meow"....no punn intended.