You killed a deer. An 80-yard run isn't out of the ordinary. Don't beat yourself up over it, and don't beat up anything else.
Okie John
The run isn't what bothers me. It's the zero blood left behind. Not a drop. No exit wound. Bad bullet for the gun/distance. Probably a better round for a longer 300-400 yard shot but it's just too fast/soft at 75 yards to get any penetration.. Just giving a review/public service on it.
