Impact: Sorry to hear how things turned out for you.
I'm not real clear on your bullet placement, because you've indicated you placed the cross hairs on the side of the deer and shot, and then indicate that the front legs were not functioning
. But then refered to the second hit as "...another good lung shot too" leaving me to assume they were both lung shots. (which wouldn't explain the front legs not working)
Was there no blood trail to follow, and if so did you inspect the blood to know if it was in fact a lung shot deer?
If you shot too far back, (gut shot?) it could be a long night for a really good tracker. But again, with both front legs gone, I wonder about it being a lung shot.... And I mean, I just can't imagine it running around the timber on it's hind legs...
Well, I don't know how it went down, but generally giving a deer a half hour to expire before you rush up on 'em is better than trying to keep up with 'em as they're bolting once they've been shot.
Anyway, sounds like you've got your mind made up on the head/neck shot concept, but in any case I'd not get too hung up on the one-shot, one-kill thing. I mean, I try to operate on that premise too, but still, if the animal is mobile, feel free to place another round on target, because it's better to have to shoot your game two or even three times, then to have a lost deer.
My boy shot a deer 3 or 4 years ago that we never recovered. Got to snowing too hard and we just lost the trail. I know what you're going through, it does make ya feel sick.