my 1st 2nd and 3rd choices are a chest shot every time . I'm not that desperate to kill a deer these days as to up the % of loosing one by taking a neck shot really .
I sort of agree with this in the sense that a chest shot deer, even if it runs and you never see it again, is dead and it is probably dead within 30 seconds of you firing the shot.
The other side to it is that I often shoot sika in thick cover (tall rushes mostly) along the edges of forestry replantings. If you waited to get a chest shot you could, honestly, stalk for years and never pull the trigger as mostly all you see is the head and neck above the rushes. You also can't have a runner as any deer that runs will go into the replanting which is still waist deep in brash from the clearfelling, plus the rushes and new trees. Even with a dog significant parts of such ground is simply physically impossible to get into and certainly presents a significant risk to the lone stalker in the pitch dark. Under these circumstances a head or neck shot is often the only option. I do my best to minimize welfare issues by only taking such shots with the deer facing directly towards or away from me.
One of the most interesting "runners" I witnessed was shot by a mate who phoned me and asked for help in the search. It was a sika calf chest shot in a very dark forestry track at last light. Initially he could find no trace of it but after some crawling about I found where it was standing and it looked to me like the shot had knocked it off balance as the slots took a stagger and had dug up the ground a little attempting to remain upright. I also spotted, after considerable searching, a "line" in the dew on the grass and by following it was able to pick his bullet off the ground and return it to him, pretty remarkable in itself. Hopefully this highlights that it was a very thorough and careful search indeed. We found no blood, hair or other signs from the deer, apart from those discussed, that it was hit. Despite further searching we were unable to find it. About two weeks later I found it some 250 - 300 yards away in the opposite direction to that in which he thought it had run, and the signs indicated it probably did run in. The weather had been cold and so it was fairly well preserved and appeared to have been nicely hit in the chest with the bullet going in about the shoulder and exiting behind the ribs on the far side. It was a 308 and the distance was about 40 - 50 yards. We had to conclude that not only had it run in the opposite direction to what we thought but it had probably almost brushed past the shoulder of my mate as it ran past him.
I guess what I'm trying to say is that sometimes necessity, and even welfare issues, mean that chest shots may not always be possible and also that "strange stuff" happens no matter how careful you are, how big a hole you make, how well hit the deer is and how careful your follow up is. Who'd have thought you could shoot a small calf right through the chest with a 308 at close range, pick up the expanded bullet off the grass and yet fail to recover the deer?
