I've killed deer with a .44 mag Marlin, 30-06, and most recently a .243. I shot my buck this past year with 100 gr .243 American Whitetail. Hit him right behind the shoulder at 20 yards. I didn't find a single drop of blood until I found the deer. Thankfully it was in the snow so the tracking was easy. Upon further inspection, the entrance hole was smaller than my pinky and there was no exit wound. I love that gun and it drives tacks, but I feel like I need to go to a larger caliber next year.