I think your first issue is whether you can control a snub .357. A 2.5-inch barelled M-19 was right at the limit for me, and I traded it off. I have a Ruger SP-101 that I haven't shot yet, but will probably limit .357 use in it to Remington's midlevel load. Mostly, this three-inch gun will eat .38 ammo.

That said, when I wanted expansion in a snub, I leaned toward 140 grain bullets. Remington's is probably more likely to open quickly than is Hornady's, making the latter better for larger animals. It all depends on what your expected target is. (Not sure if Remington still makes 140 grain .357's.)

I was pretty sure that recent Federal 158 grain Hydra-Shoks would open some, due to the design. I avoided full 125 grain loads, because they are very hard on guns and the blast was very objectionable. If you want to use them, I think the M-686 or the Ruger GP-100 are better vehicles than K- or J-frame snubs.

I researched the velocity of the 140 grainers from snub and three-inch guns, and they'd usually exceed 1200 FPS. And penetration should be ample for humans, cougars and similar animals. Certainly more than enough for even really large snakes. I'd be pretty sure that nothing more would be needed, even on big anacondas or reticulated pythons. (We have some readers who live or go where these snakes live.)

For bears, I'd worry less about expansion and rely on deeper penetration and pinpoint placement. And I'd use a longer barrel if I could, and choose 158 grain or Remington's 165 grain load. I don't like heavier bullets in this bore size. If you want heavier bullets, shoot them in a .44 Magnum.