Have shot a few deer with my 44 mag Marlin. Never tried more bullet than 240 Nosler JHP or XTP. Shots 80-100yds. Never stopped one in an animal, but I did dig 2 out of the dirt behind after the shot. Both bullets went 5-6" in the dirt after angled broadside pass-through. For deer, I would not go heavier or tougher than a JHP in 240, and for lung shots a 200 XTP would likely be ideal, though I've never done it. Deer are soft, and more bullet just isn't required.
