yes, .460 is far more practical than 10mm, even if you AINT already got a .45, because of the price of practice components, mags, etc. However, with standard bullets, the recoil of either one is pretty severe, especially if you want penetration. My answer was the hollowbased, 90 gr .45 swc, at 2100 fps in a lw Commander. 880 ft lbs, LOTS of penetration, no more recoil than plus P 185 gr .45's. Which is pretty serious, actually, in a 7.8", 28 oz gun. That's why I decided upon the Defender length slide, a Commander length barrel, and a 4 oz muzzlewt on the exposed 1" of barrel.
Muzzlewt is made from a chunk of slide, welded to the barrel sleeve (threaded and silver soldered to the barrel) front sight on the muzzlewt. Lead in the area of the wt where spring used to be. Practice mostly with 9mm, but enough .45's to make handling this little pussycat no big deal. Have to head-shoot big critters anyway, and many of their "charges" are just bluffs, or will veer off or stop at a round over their heads (at 30 ft). If you WOUND them, though, it's ON, so don't fire for blood beyond 20 ft or so. They are hitting 50 fps, so you only get 1/2 a second in which to brain the critter. So best have .17 second splits, and 3-4 tries at the brain, not the .50 second splits of the .50 desert eagle, or the 1 full second splits of the .454 SA revolver.
most mountain lions aint very big, so the 70 gr Split Nose, pre-frag, at 2300 fps, might be a better bet, chest hits, because they are very sneaky and very fast. Regardless of where you are, men are by FAR the more common and the more dangerous threats, even if they DON'T have guns.