Tom,

No offense, and I am sure that a .357 with a stout load will dispatch a two or four legged varmit; but I ask what about follow up? The first round of a 180gr out of a model 66 is going to hurt.

I would recommend a 44mag. Even a 240 gr lead RN or SWC moving at 1000fps is going to break bones (which is what you want when faced with a cougar) but the recoil will allow you to have a good follow up second through sixth shot.

I carry a 629 Compact Carry 3" ported 44 mag.

No, not as light as my J Frame model 60, but the 44Mag is good to go.

If you don't reload, you could use a 44 Special factory load.

Cheers, Doug