I wasn't going to bring this up, but - I neck shot a deer once, dropping it on the spot with a .45 round ball from my deep groove Bauska. The deer was facing us, Tracy and I as we walked along a trail.
Immediately upon hitting the ground, it started thrashing around to get up. I could see the hole, just off to the left side of centre. I'd missed the spine and there was hardly any blood, just a spot. I dropped my rifle and attempted to use Tracy's .36, (loaded with a 228gr.maxiball) to head shoot it in order to finish it off. I rushed up within 20' of the deer and snapped off the shot at it's head, just as it swung it's head to one side. The bullet entered the neck, hit the spine then ran down alongside the spine to stop between the shoulders - about 11" or 12" penetration. It had no effect, except to hasten it's attempts to gain it's feet. She handed me my rifle wherein I dumped in a 'bunch'/'some'/'enough' powder straight out of the horn into the muzzle, set a ball on top and pushed it down bare with the rod, capped and then finished it off with a side head shot from point blank. As the ball was .009" larger than the bore, there was no chance it would roll out. This whole disaster took about 1 minute, maybe. At least the deer wasn't lost.
For those who think you never need a second shot, I don't believe it. All you need to do is make a poor shot, as I did and a second or third is needed. If it goes bad, it sometimes goes very badly.
Yeah - mistakes were made - I should have reloaded my own rifle and shot the deer in the body, or I should have shot it in the body with Tracy's rifle. Not wanting to "spoil" the shoulder, is false economy.
Of course, had I shot a bit lower on the chest, not the neck and centred for the lungs, I'd have probably dumped that little buck right there as well and hurt no amount of meat and guaranteed the kill with the first shot.