I've shot over fifty deer with the 357mag in handguns and another seven or eight in a Marlin lever gun. I've used bullets ranging in weight from 140g up to 180g in both type guns. Most of the deer shot were shot with Hornady XTP bullets. All that being said, DO NOT select the 125g bullet for your bullet of choice. I've recovered a lot of bullets from those deer and although the 125g can and will kill a deer, it's simply not the best choice in bullet weight. Even more so in a rifle. Most of the deer I shot were shot with the 158g XTP and expansion was excellent and about half were pass throughs. I've never lost a deer with the 357mag that I hit. Using the 180g XTP bullets, about 3/4 were pass throughs and expansion was still very good. As the bullet weight goes up, so does penetration. Over expansion isn't necessarily a good thing. It is to a point, but too much reduces penetration and you begin to lose weight as the bullet can fragment. Your choice, I'm just sharing my forty plus years of handgun deer hunting. Good luck with the new gun.