I come right up the front leg and when I get to where the body swells out, I pull the trigger. I hunted with a .243 for 20 years and killed 2-3 deer every year. I never had one go out of sight and most dropped within 20 yards.
I shoot the same with a handgun and have experienced the same good results.
Once I let an outdoor magazine article convince me that I should shoot a deer through the lungs so the first buck that came along I shot him dead through both lungs. Do deer have after burners? This one kicked it in high gear and went off through the woods and out of sight. In actuality, I found the deer 20 minutes later about 100 yards through some very rough stuff. It will definately kill a deer but I will stay with my "shoulder" shot.