Funny I've been contemplating the same question with my .357 but between 180 or a 200 grain cast. Now all I am is more confused.
I'm real new to handgun hunting , why are guys shying away from heavy cast ??
I think the other replies to your question were good, but I'd add the suggestion that as a new handgun hunter you might want to do some reading/research into the pros and cons of cast and jacketed bullets for handgun hunting. I'd start with Paco Kelly's articles at leverrifles.com, John Linebaugh's website, and the excellent downloadable book on cast bullets for hunting by Glen Fryxell at
http://www.lasc.us/articlesfryxell.htm.I've used both cast and jacketed bullets for handgun hunting. I carry mostly my own cast bullets in my 45 Colt guns, but jacketed bullets in my 44's and about 50:50 in my 357's. It's more a matter of what your experiences have been than which is "better".
But if I had to generalize, I'd say this: a heavy-for-caliber cast bullet is a penetrator, ideally suited for heavier game such as elk, moose, feral hog, and bear, whereas an expanding jacketed bullet (or HP cast, for that matter... I'm just beginning to experiment with some of these, and they're a blast, literally!) is better for lighter game such as deer and varmints.
Example: this 300 gr WFN-type bullet cast from "sweetened" WW alloy and dropped into cold water has a BHN of about 20. I used to hunt with this bullet a lot, driven at about 1300 fps out of a Ruger Bisley. It pencilled right through a couple of deer, including one doe I shot in the shoulder with the bullet exiting out her opposite flank. These deer ran half a mile before dropping, the latter doe in dense swamp/woods that took several hours' tracking to finally collect. This bullet was recovered from a sandbox after it drilled through a 14" seasoned maple log. That is just too much penetration for deer hunting, IMHO.
That bullet in that alloy is too hard. I now cast that bullet out of a softer mix to about BHN 10-11, and it flat devastates anything I've shot with it, DRT. It expands and destroys tissue beautifully. I don't hunt with what most people call "hard cast" bullets any more. My experience, like that of Kelly and Fryxell and others, points to softer alloys being much better for clean kills.
Example #2 is this CorBon 115 gr 9mm slug (MV~1300 fps) I recovered from a whitetail I shot from a tree stand, shooting almost directly down and into the chest cavity. The bullet penetrated through the chest cavity and was recovered under the skin in the shape you see it there. The deer dropped like it had been pole-axed, and its chest cavity was red jelly.
Every deer I've shot with JHP bullets has dropped pronto. But there's a downside: I shot a raccoon the night before the deer, from the same stand, with the same gun & bullet... he freakin' exPLODED, and his mature bull coon pelt was destroyed. If I was hunting coons or yotes for fur, I'd not use this bullet but rather a cast non-expanding bullet.
Hope this doesn't just muddy the waters for you. The point is that there is no simple answer to the question of which bullet is better until you take into consideration the load, the gun, and the game.