No mans land is no where near shooting a deer in his chest. No mans land is above the lungs and below the spine on a broadside shot. Imo you may have screwed up if you don't see him again bc not shooting at 180yds when your dialed in that good at 150 is a definite missed oppurtunity for you. Wouldn't have hesitsted for a second to take that shot at all and neither should you. That small difference in yardage is nothing for a rifle at all. Anyways good luck.